Population and applicability

Who was studied?

A study result starts with the people and settings that produced it. This ledger shows the population fields recorded for reviewed or published outcome, safety, and body-site claims - and says “Not reported” instead of guessing.

Last updated August 21, 2026

How to use this page

Missing reporting is a research limitation. It is not proof that a group was excluded, and it is not proof that a treatment does or does not work for that group. Geography, race, ethnicity, and skin tone or phototype answer different questions and remain separate here.

Applicability describes how far one claim can travel beyond the evidence behind it. It does not estimate a personal result.

Confidence and limits

A peer-reviewed randomized phase 2 study enrolled 171 adults with extensive nonsegmental vitiligo. At week 24, the mean total-body score improved by 15.7% to 19.1% across the studied povorcitinib groups while the placebo group worsened by 2.3%; the study reported limited demographic diversity. A later descriptive post hoc analysis followed 103 people who received povorcitinib throughout the study. It reported week-52 VASI50 response proportions from 25.8% for feet to 57.3% for head and neck outside the face. It had no placebo comparison at week 52 and cannot predict an individual site. The registries list 467 participants in STOP-V1 and 450 in STOP-V2. Incyte later said that at week 52, 18.9% reached F-VASI75 (at least 75% improvement from baseline in the facial score). That was versus 6.8% with placebo in STOP-V1, and 18.9% versus 3.1% in STOP-V2. Those phase 3 percentages are sponsor-reported topline results, not posted registry results or peer-reviewed findings.
Limited evidence. Phase 3 percentages remain sponsor toplines, no full result tables were posted, no direct treatment comparison was made, and group results do not predict an individual outcome.
The phase 2 publication reported a similar incidence of grade 3 or higher treatment-emergent adverse events across study groups, and no new safety signal. The phase 3 registries excluded people with several infection, cancer, cardiovascular, clotting, pregnancy, laboratory, and prior-treatment risks. The reviewed sources do not include an approved povorcitinib vitiligo product label. So they do not supply a complete labeled contraindication, warning, interaction, monitoring, pregnancy, or long-term safety profile. Safety language from another JAK medicine cannot be transferred as if it were povorcitinib evidence.
Limited evidence. Shorter-term study reporting and eligibility exclusions do not create a complete contraindication, warning, interaction, monitoring or long-term safety profile.
Ask what findings support psoriasis and what remains uncertain. Generalized pustular psoriasis and erythroderma require same-day specialist assessment. Seek urgent clinical help for a sudden widespread pustular eruption or extensive, rapidly spreading redness. Feeling acutely unwell increases the urgency, but do not wait for fever or other systemic symptoms.
Limited evidence. A photo, questionnaire or checklist cannot confirm psoriasis, identify a subtype or decide urgency for an individual. Other conditions can look similar.
Bring your medicine list and ask how infections, vaccines, pregnancy or pregnancy plans, other health conditions and prior treatment reactions change the options. Each medicine has product-specific limits and monitoring rather than one class-wide checklist.
Limited evidence. This checklist cannot identify a contraindication, interpret a test, tell you to stop a medicine or replace the current label and clinician instructions.
Generalized pustular psoriasis and erythroderma require same-day specialist assessment. Seek urgent clinical help for a sudden widespread pustular eruption or extensive, rapidly spreading redness. Feeling acutely unwell increases the urgency, but do not wait for fever or other systemic symptoms.
Reasonably supported. NICE is UK guidance. This copy does not identify a subtype, assess an individual emergency, or replace local emergency and specialist pathways.
Medical phototherapy can treat psoriasis in the skin. It does not treat joint inflammation and is not a treatment for psoriatic arthritis. Joint concerns need a separate clinical assessment.
Reasonably supported. This boundary does not decide whether phototherapy fits a reader’s skin or diagnose joint disease.
No. A commercial tanning device and prescribed narrowband UVB are not interchangeable. A tanning booth is not a shortcut around a medical light-treatment plan.
Limited evidence. The sources support group-level clinical context or exact manufacturer and regulator facts. They do not choose a setting or device, provide treatment settings, establish individual safety, diagnose a reaction or fault, authorize resale, or replace the current manual and professional support.
Use these questions to prepare, observe, record, and report. Your prescriber decides whether to start, continue, change, pause, or restart treatment, and the current instructions for your exact device govern its operation.
Limited evidence. The sources support group-level clinical context or exact manufacturer and regulator facts. They do not choose a setting or device, provide treatment settings, establish individual safety, diagnose a reaction or fault, authorize resale, or replace the current manual and professional support.
Guidelines describe reviewing the diagnosis and how it appears, current medicines, sensitivity to light, skin-cancer history, prior ultraviolet treatment, pregnancy, and other individual risks. Use this as a conversation starter - not as a self-test that says NB-UVB is or is not safe for you.
Limited evidence. The sources support group-level clinical context or exact manufacturer and regulator facts. They do not choose a setting or device, provide treatment settings, establish individual safety, diagnose a reaction or fault, authorize resale, or replace the current manual and professional support.
Several common medicine groups can make skin react more strongly to ultraviolet light. Your prescriber reviews everything you take before and during treatment. Bring the complete list, and do not stop or change anything on your own.
Limited evidence. The sources support group-level clinical context or exact manufacturer and regulator facts. They do not choose a setting or device, provide treatment settings, establish individual safety, diagnose a reaction or fault, authorize resale, or replace the current manual and professional support.
Ask your team, and ask before the sunny week rather than after it. The light you are given and the light outside are the same kind of energy, so time outdoors is not separate from your course. The British patient leaflet asks people not to sunbathe or use a sunbed for the whole of a course. It also asks them to keep out of the sun enough that skin does not burn.
Limited evidence. The sources support group-level clinical context or exact manufacturer and regulator facts. They do not choose a setting or device, provide treatment settings, establish individual safety, diagnose a reaction or fault, authorize resale, or replace the current manual and professional support.
Some ordinary products change how skin answers ultraviolet light. The British leaflet asks people not to wear perfume, deodorant, aftershave or other cosmetics to a treatment. Some of them contain substances that make skin more sensitive to light, and the result can be patchy discoloured skin that takes months to fade.
Limited evidence. The sources support group-level clinical context or exact manufacturer and regulator facts. They do not choose a setting or device, provide treatment settings, establish individual safety, diagnose a reaction or fault, authorize resale, or replace the current manual and professional support.
The leaflet treats them as one account, and it is honest that the account is estimated rather than measured. It says the full risk of this particular light is not known, and that the estimate it gives assumes narrowband UVB behaves like sunlight. On that assumption, courses repeated across a lifetime raise the risk of treatable skin cancer.
Limited evidence. The sources support group-level clinical context or exact manufacturer and regulator facts. They do not choose a setting or device, provide treatment settings, establish individual safety, diagnose a reaction or fault, authorize resale, or replace the current manual and professional support.
Use only the eye protection approved for your exact device or by your phototherapy team. Keep it on unless that team gives you a specific plan for treating the eyelids.
Limited evidence. The sources support group-level clinical context or exact manufacturer and regulator facts. They do not choose a setting or device, provide treatment settings, establish individual safety, diagnose a reaction or fault, authorize resale, or replace the current manual and professional support.
No. A color change can be subtle or hard to interpret, especially in deeper skin tones. Know what your skin looks and feels like before treatment, and report pain, tenderness, heat, swelling, blistering, marked itching, or another concerning change. No visible redness does not mean you should change the plan yourself.
Limited evidence. The sources support group-level clinical context or exact manufacturer and regulator facts. They do not choose a setting or device, provide treatment settings, establish individual safety, diagnose a reaction or fault, authorize resale, or replace the current manual and professional support.
Yes. Using the same kind of equipment does not make the reasons for treatment, alternatives, or monitoring identical across conditions. Vitiligo decisions should use vitiligo guidance as well as phototherapy guidance. Use psoriasis-specific guidance for psoriasis decisions.
Limited evidence. The sources support group-level clinical context or exact manufacturer and regulator facts. They do not choose a setting or device, provide treatment settings, establish individual safety, diagnose a reaction or fault, authorize resale, or replace the current manual and professional support.
Stop and use the manufacturer’s official support route rather than testing, opening, bypassing, or repairing the device yourself. If you are in the United States, use the FDA route when a medical-device problem should also be reported to the regulator.
Limited evidence. The sources support group-level clinical context or exact manufacturer and regulator facts. They do not choose a setting or device, provide treatment settings, establish individual safety, diagnose a reaction or fault, authorize resale, or replace the current manual and professional support.
The research behind this page cannot say. The largest pooled review of narrowband UVB counted how many people had responded at 6 months and at 12 months. But each count came from a different set of studies. It never followed one group of early responders to see how many later stalled. A plateau in your own course is still real. How common that is across everyone is not something these numbers can show.
Limited evidence. The sources support general course-planning and review concepts only. They do not provide a regimen, determine when to resume or stop treatment, diagnose a reaction, or predict an individual outcome.
The same pooled review answers that, if you read its percentages the other way round. At 12 months it reports two separate pools. One is 512 people across 8 studies, for the quarter-back bar. The other is 540 people across 9 studies, for the three-quarters bar: 25.0% had less than a quarter of their pigment back. About one person in four. That is the 75.0% our phototherapy page publishes, taken away from 100. 64.3% had less than three quarters back, from the same page’s 35.7%. On hands and feet, pooled separately after at least 6 months, 89.0% had less than a quarter back, from that page’s 11.0%. Nobody reached three quarters.
Limited evidence. The sources support general course-planning and review concepts only. They do not provide a regimen, determine when to resume or stop treatment, diagnose a reaction, or predict an individual outcome.
Maintenance means continuing some treatment after a response settles, to try to hold the result. After a plateau, a prescriber may continue, taper, pause, or stop the course. That decision belongs to your prescriber, working from your record and current guidance.
Limited evidence. The sources support general course-planning and review concepts only. They do not provide a regimen, determine when to resume or stop treatment, diagnose a reaction, or predict an individual outcome.
Narrowband UVB can cause erythema, including painful sunburn-type reactions, and requires a defined reaction and contact plan.
Reasonably supported. A website cannot grade a reaction, estimate personal risk, or replace the treating team’s instructions.

Applicability check

Who was studied?

These fields show what the cited evidence reports about the people and body sites behind outcome or safety claims. “Not reported” means the reviewed source omitted the field; “Pending exact source review” means SteadySkin has not made that determination yet.

A peer-reviewed randomized phase 2 study enrolled 171 adults with extensive nonsegmental vitiligo. At week 24, the mean total-body score improved by 15.7% to 19.1% across the studied povorcitinib groups while the placebo group worsened by 2.3%; the study reported limited demographic diversity. A later descriptive post hoc analysis followed 103 people who received povorcitinib throughout the study. It reported week-52 VASI50 response proportions from 25.8% for feet to 57.3% for head and neck outside the face. It had no placebo comparison at week 52 and cannot predict an individual site. The registries list 467 participants in STOP-V1 and 450 in STOP-V2. Incyte later said that at week 52, 18.9% reached F-VASI75 (at least 75% improvement from baseline in the facial score). That was versus 6.8% with placebo in STOP-V1, and 18.9% versus 3.1% in STOP-V2. Those phase 3 percentages are sponsor-reported topline results, not posted registry results or peer-reviewed findings.

Age range: Adults.
Condition subtype: Nonsegmental vitiligo.
Severity or extent: Phase 2 studied extensive disease. The phase 3 registries required minimum total-body and facial involvement using prespecified body-surface and VASI thresholds.
Sample size: Phase 2 randomized 171 adults. The phase 3 registries list 467 participants in STOP-V1 and 450 in STOP-V2.
Geography and care setting: A multicenter study conducted in Canada and the United States.
Skin tone or phototype: The descriptive extension analysis reported Fitzpatrick type subgroups.
Race: The descriptive extension analysis reported White and non-White subgroups.
Ethnicity: The phase 2 publication reported 32 of 171 participants (18.7%) as Hispanic.
Body sites: Facial and total-body scores were reported. A descriptive post hoc analysis of 103 extension-evaluable participants reported week-52 VASI50 response proportions from 25.8% for feet to 57.3% for head and neck outside the face. It was pooled, post hoc and lacked a week-52 placebo comparator.

What that means for this page: The peer-reviewed numeric result applies most directly to adults with extensive nonsegmental vitiligo resembling the phase 2 population. The separate STOP-V1 and STOP-V2 percentages are sponsor toplines for phase 3 adults meeting registry-defined minimum facial and total-body involvement. Phase 3 demographic subgroup tables are not public. Limited phase 2 demographic diversity and descriptive post hoc subgroup and body-region analyses restrict generalization; group results do not predict an individual or body-site response.

The phase 2 publication reported a similar incidence of grade 3 or higher treatment-emergent adverse events across study groups, and no new safety signal. The phase 3 registries excluded people with several infection, cancer, cardiovascular, clotting, pregnancy, laboratory, and prior-treatment risks. The reviewed sources do not include an approved povorcitinib vitiligo product label. So they do not supply a complete labeled contraindication, warning, interaction, monitoring, pregnancy, or long-term safety profile. Safety language from another JAK medicine cannot be transferred as if it were povorcitinib evidence.

Age range: Adults.
Condition subtype: Nonsegmental vitiligo.
Severity or extent: Extensive disease in phase 2.
Sample size: 168 treated adults in the phase 2 safety population.
Geography and care setting: A multicenter study conducted in Canada and the United States.
Skin tone or phototype: The phase 2 publication reported baseline Fitzpatrick skin-type categories.
Race: The phase 2 publication reported baseline race categories and noted limited demographic diversity.
Ethnicity: The phase 2 randomized population included 32 of 171 participants (18.7%) identified as Hispanic.
Body sites: Not reported

What that means for this page: Shorter-term study reporting and phase 3 eligibility rules do not supply a complete commercial-product safety profile, long-term risk estimate, pediatric evidence, or personal risk calculation.

Ask what findings support psoriasis and what remains uncertain. Generalized pustular psoriasis and erythroderma require same-day specialist assessment. Seek urgent clinical help for a sudden widespread pustular eruption or extensive, rapidly spreading redness. Feeling acutely unwell increases the urgency, but do not wait for fever or other systemic symptoms.

Age range: Not reported
Condition subtype: Not reported
Severity or extent: Not reported
Sample size: Not reported
Geography and care setting: Sources are a UK guideline and US patient-education and label pages. None is a study. None reports an enrolled study population.
Skin tone or phototype: Not reported
Race: Not reported
Ethnicity: Not reported
Body sites: Not reported

What that means for this page: NICE names two presentations needing same-day specialist care: generalised pustular psoriasis and erythroderma. Neither source is a study of who develops these or how often. A written description cannot decide urgency for one reader. That judgment needs in-person clinical assessment.

Bring your medicine list and ask how infections, vaccines, pregnancy or pregnancy plans, other health conditions and prior treatment reactions change the options. Each medicine has product-specific limits and monitoring rather than one class-wide checklist.

Age range: Not reported
Condition subtype: Not reported
Severity or extent: Not reported
Sample size: Not reported
Geography and care setting: Sources are a UK guideline and US patient-education and label pages. None is a study. None reports an enrolled study population.
Skin tone or phototype: Not reported
Race: Not reported
Ethnicity: Not reported
Body sites: Not reported

What that means for this page: The systemic guideline and the Icotyde label each set their own precautions and monitoring. Neither is one class-wide rule. Neither source reports how often a reader hits an infection, vaccine or pregnancy-planning question. This stays a prompt to ask a clinician, not a safety determination.

Generalized pustular psoriasis and erythroderma require same-day specialist assessment. Seek urgent clinical help for a sudden widespread pustular eruption or extensive, rapidly spreading redness. Feeling acutely unwell increases the urgency, but do not wait for fever or other systemic symptoms.

Age range: Not reported
Condition subtype: Not reported
Severity or extent: Not reported
Sample size: Not reported
Geography and care setting: NICE CG153 is a UK clinical guideline for assessing and managing psoriasis in adults, children and young people across primary and specialist care. It reports no study population of its own.
Skin tone or phototype: Not reported
Race: Not reported
Ethnicity: Not reported
Body sites: Not reported

What that means for this page: This is UK clinical guidance directing same-day specialist assessment for these patterns, not a study of how many people develop them or how they respond to it. It does not identify a subtype, quantify individual risk, or replace a local emergency or specialist pathway.

Medical phototherapy can treat psoriasis in the skin. It does not treat joint inflammation and is not a treatment for psoriatic arthritis. Joint concerns need a separate clinical assessment.

Age range: Not reported
Condition subtype: Not reported
Severity or extent: Not reported
Sample size: Not reported
Geography and care setting: One source is a UK narrowband UVB clinical guideline, one a UK hospital patient leaflet last updated June 2022, and one US patient education page on psoriatic-arthritis diagnosis. None reports a study population.
Skin tone or phototype: Not reported
Race: Not reported
Ethnicity: Not reported
Body sites: Not reported

What that means for this page: These are guidance and patient-education documents, not a study of joint outcomes. They establish that phototherapy targets skin and not joints, and that joint disease needs separate clinical assessment. They do not quantify how often skin and joint disease occur together or assess an individual reader.

No. A commercial tanning device and prescribed narrowband UVB are not interchangeable. A tanning booth is not a shortcut around a medical light-treatment plan.

Age range: Not reported
Condition subtype: Not reported
Severity or extent: Not reported
Sample size: Not reported
Geography and care setting: One source is the UK narrowband UVB guideline for clinic and home services. The other is a UK hospital unit patient leaflet, last updated June 2022 and past its own review date. Neither reports a study population.
Skin tone or phototype: Not reported
Race: Not reported
Ethnicity: Not reported
Body sites: Not reported

What that means for this page: Both sources are guidance, not a study. They separate sunlight, tanning devices, narrowband UVB and other light treatments because the light source, purpose and safety steps differ. Neither compares outcomes between a tanning bed and prescribed treatment, and neither describes people who tried a substitute.

Use these questions to prepare, observe, record, and report. Your prescriber decides whether to start, continue, change, pause, or restart treatment, and the current instructions for your exact device govern its operation.

Age range: Not reported
Condition subtype: Not reported
Severity or extent: Not reported
Sample size: Not reported
Geography and care setting: One source is the UK narrowband UVB guideline for clinic and home services. The other is a UK hospital unit patient leaflet, last updated June 2022 and past its own review date. Neither reports a study population.
Skin tone or phototype: Not reported
Race: Not reported
Ethnicity: Not reported
Body sites: Not reported

What that means for this page: These are guidance documents. They place assessment, prescribing, monitoring and decisions about reactions within a clinical service. They report no patient group and set no rule a reader can apply without their own care team.

Guidelines describe reviewing the diagnosis and how it appears, current medicines, sensitivity to light, skin-cancer history, prior ultraviolet treatment, pregnancy, and other individual risks. Use this as a conversation starter - not as a self-test that says NB-UVB is or is not safe for you.

Age range: Not reported
Condition subtype: Not reported
Severity or extent: Not reported
Sample size: Not reported
Geography and care setting: The narrowband UVB guideline is written for UK phototherapy services, in clinic and at home. It reports no study population of its own.
Skin tone or phototype: Not reported
Race: Not reported
Ethnicity: Not reported
Body sites: Not reported

What that means for this page: The guideline lists factors a clinician reviews before treatment, such as current medicines, light sensitivity, skin-cancer history and pregnancy. It gives this as clinical assessment, not a checklist that tells a reader whether treatment is safe for them. It reports no patient group.

Several common medicine groups can make skin react more strongly to ultraviolet light. Your prescriber reviews everything you take before and during treatment. Bring the complete list, and do not stop or change anything on your own.

Age range: Not reported
Condition subtype: Not reported
Severity or extent: Not reported
Sample size: Not reported
Geography and care setting: One source is the UK narrowband UVB guideline for clinic and home services. The other is a UK hospital unit patient leaflet, last updated June 2022 and past its own review date. Neither reports a study population.
Skin tone or phototype: Not reported
Race: Not reported
Ethnicity: Not reported
Body sites: Not reported

What that means for this page: The guideline and the leaflet name medicine groups that can raise light sensitivity, including some antibiotics, some diuretics, and herbal products such as St John’s wort. Neither is a study and neither reports how often a reaction follows. Taking one of these does not by itself rule treatment in or out.

Ask your team, and ask before the sunny week rather than after it. The light you are given and the light outside are the same kind of energy, so time outdoors is not separate from your course. The British patient leaflet asks people not to sunbathe or use a sunbed for the whole of a course. It also asks them to keep out of the sun enough that skin does not burn.

Age range: Not reported
Condition subtype: Not reported
Severity or extent: Not reported
Sample size: Not reported
Geography and care setting: The patient leaflet is written for a UK hospital unit whose staff check skin at each visit. It has not been updated since June 2022 and its review date has passed. It reports no study population.
Skin tone or phototype: Not reported
Race: Not reported
Ethnicity: Not reported
Body sites: Not reported

What that means for this page: The leaflet asks people not to sunbathe or use a sunbed for a whole course, and to keep skin from burning. It sets no rule for a home panel and puts no number on how much time outdoors adds for one person. It reports no patient group.

Some ordinary products change how skin answers ultraviolet light. The British leaflet asks people not to wear perfume, deodorant, aftershave or other cosmetics to a treatment. Some of them contain substances that make skin more sensitive to light, and the result can be patchy discoloured skin that takes months to fade.

Age range: Not reported
Condition subtype: Not reported
Severity or extent: Not reported
Sample size: Not reported
Geography and care setting: One source is the UK hospital unit leaflet, past its review date. The other two are current US prescribing information for Protopic (tacrolimus) and Elidel (pimecrolimus). None reports a study population for this point.
Skin tone or phototype: Not reported
Race: Not reported
Ethnicity: Not reported
Body sites: Not reported

What that means for this page: The leaflet asks people to arrive without perfume, deodorant or cosmetics and to use only a suitable moisturiser before a session. The Protopic (tacrolimus) and Elidel (pimecrolimus) labels tell people using those products to avoid ultraviolet treatment and limit sun. None of the three is a study, and none names a product, order or timing for one person.

The leaflet treats them as one account, and it is honest that the account is estimated rather than measured. It says the full risk of this particular light is not known, and that the estimate it gives assumes narrowband UVB behaves like sunlight. On that assumption, courses repeated across a lifetime raise the risk of treatable skin cancer.

Age range: Not reported
Condition subtype: Not reported
Severity or extent: Not reported
Sample size: Not reported
Geography and care setting: The patient leaflet is written for a UK hospital phototherapy unit. It has not been updated since June 2022 and its review date has passed. It reports no study population.
Skin tone or phototype: Not reported
Race: Not reported
Ethnicity: Not reported
Body sites: The leaflet says the estimated skin-cancer risk is lower for someone whose face is not treated. It gives no other body-site breakdown.

What that means for this page: The leaflet states plainly that the full risk of narrowband UVB is not known, and that its lifetime-risk estimate assumes the treatment behaves like sunlight. Its one-in-ten skin-cancer figure is a UK population figure, not a personal risk. It reports no patient group.

Use only the eye protection approved for your exact device or by your phototherapy team. Keep it on unless that team gives you a specific plan for treating the eyelids.

Age range: Not reported
Condition subtype: Not reported
Severity or extent: Not reported
Sample size: Not reported
Geography and care setting: One source is the UK narrowband UVB guideline. The other two are manufacturer manuals and support pages for named phototherapy units. None reports a study population.
Skin tone or phototype: Not reported
Race: Not reported
Ethnicity: Not reported
Body sites: The eyes and eyelids. The guideline covers eye protection during treatment; treating the eyelid skin itself is described as a separate clinical decision.

What that means for this page: The guideline recommends ultraviolet-protective goggles during treatment, and the device manuals state that protection is model-specific. None is a study, and none certifies a particular product sold today. An eyelid exception is described as a clinical decision, not a step to take at home.

No. A color change can be subtle or hard to interpret, especially in deeper skin tones. Know what your skin looks and feels like before treatment, and report pain, tenderness, heat, swelling, blistering, marked itching, or another concerning change. No visible redness does not mean you should change the plan yourself.

Age range: Not reported
Condition subtype: Not reported
Severity or extent: Not reported
Sample size: Not reported
Geography and care setting: One source is the UK narrowband UVB guideline for clinic and home services. The other is a UK hospital unit patient leaflet, last updated June 2022 and past its own review date. Neither reports a study population.
Skin tone or phototype: Not reported
Race: Not reported
Ethnicity: Not reported
Body sites: Any treated skin, both depigmented and surrounding. The guidance gives no body-site breakdown for recognising a reaction.

What that means for this page: Both sources are guidance. They ask people to know their own skin and to report pain, heat, swelling, blistering or marked itch rather than judge a reaction by colour. Neither reports a patient group and neither sets a colour threshold, so this record cannot describe one by skin tone.

Yes. Using the same kind of equipment does not make the reasons for treatment, alternatives, or monitoring identical across conditions. Vitiligo decisions should use vitiligo guidance as well as phototherapy guidance. Use psoriasis-specific guidance for psoriasis decisions.

Age range: Not reported
Condition subtype: Not reported
Severity or extent: Not reported
Sample size: Not reported
Geography and care setting: The sources are the UK narrowband UVB guideline, the 2021 UK vitiligo guideline, and the 2023 International Vitiligo Task Force statement. All are consensus guidance, not studies of a patient group.
Skin tone or phototype: Not reported
Race: Not reported
Ethnicity: Not reported
Body sites: Not reported

What that means for this page: All three sources are consensus guidance. They describe different goals, patterns, alternatives and monitoring for different conditions, and say the same equipment does not make those the same. Body areas, disease activity and other health conditions still change the decision, so it is left to a treating team.

Stop and use the manufacturer’s official support route rather than testing, opening, bypassing, or repairing the device yourself. If you are in the United States, use the FDA route when a medical-device problem should also be reported to the regulator.

Age range: Not reported
Condition subtype: Not reported
Severity or extent: Not reported
Sample size: Not reported
Geography and care setting: One source is the US FDA MedWatch reporting page. The others are manufacturer support routes for named phototherapy devices. None reports a study population.
Skin tone or phototype: Not reported
Race: Not reported
Ethnicity: Not reported
Body sites: Not reported

What that means for this page: The MedWatch page is a reporting route and the device pages are manufacturer support routes. None is a study, and none decides whether a report is required or proves that a device caused a health problem. A device fault and a health concern can occur together and still need separate routes.

The research behind this page cannot say. The largest pooled review of narrowband UVB counted how many people had responded at 6 months and at 12 months. But each count came from a different set of studies. It never followed one group of early responders to see how many later stalled. A plateau in your own course is still real. How common that is across everyone is not something these numbers can show.

Age range: Three of the pooled studies enrolled children only, 8 enrolled adults only, and 24 enrolled all ages. Reported mean ages ran from about 10 to about 49 years, and individual ages from 3 to 77.
Condition subtype: Generalized or nonsegmental vitiligo. Segmental vitiligo was not the subject of this pooled review.
Severity or extent: Extent requirements differed by study. Some required at least 2% of body surface, others 5%, 10%, 15%, 20% or more. Many studies did not state an extent.
Sample size: 1428 people across 35 prospective studies. 1201 people in 29 studies received narrowband UVB, and 227 people in 9 studies received PUVA.
Geography and care setting: The pooled studies came from Brazil, Bulgaria, Canada, Egypt, England, Greece, India, Iran, Iraq, Italy, Korea, Nepal, Norway, the Netherlands, Tunisia, Turkey and the United Arab Emirates. All were prospective studies, so treatment was given in a study setting.
Skin tone or phototype: Fitzpatrick skin types were listed study by study and spanned types I to VI, most often types II to V. Several studies did not record skin type.
Race: Not reported
Ethnicity: Not reported
Body sites: For narrowband UVB, face and neck, trunk, extremities, and hands and feet were pooled separately after at least 6 months. PUVA was not pooled by body site, because too few of the studies reported it.

What that means for this page: The 2017 review pooled separate sets of studies at 3, 6 and 12 months. It did not follow one group of early responders to count how many later stalled. The 2023 Task Force statement is expert consensus, not a patient group. Together they cannot say how common a plateau is, whether one person has reached one, or what comes next.

The same pooled review answers that, if you read its percentages the other way round. At 12 months it reports two separate pools. One is 512 people across 8 studies, for the quarter-back bar. The other is 540 people across 9 studies, for the three-quarters bar: 25.0% had less than a quarter of their pigment back. About one person in four. That is the 75.0% our phototherapy page publishes, taken away from 100. 64.3% had less than three quarters back, from the same page’s 35.7%. On hands and feet, pooled separately after at least 6 months, 89.0% had less than a quarter back, from that page’s 11.0%. Nobody reached three quarters.

Age range: Three of the pooled studies enrolled children only, 8 enrolled adults only, and 24 enrolled all ages. Reported mean ages ran from about 10 to about 49 years, and individual ages from 3 to 77.
Condition subtype: Generalized or nonsegmental vitiligo. Segmental vitiligo was not the subject of this pooled review.
Severity or extent: Extent requirements differed by study. Some required at least 2% of body surface, others 5%, 10%, 15%, 20% or more. Many studies did not state an extent.
Sample size: The review as a whole pooled 1201 people across 29 narrowband UVB studies. Each figure inverted here rests on a smaller subset. The 12-month quarter-back bar used 512 people in 8 studies. The three-quarters bar used 540 people in 9 studies. The hands-and-feet pool used 172 people in 6 studies.
Geography and care setting: The pooled studies came from Brazil, Bulgaria, Canada, Egypt, England, Greece, India, Iran, Iraq, Italy, Korea, Nepal, Norway, the Netherlands, Tunisia, Turkey and the United Arab Emirates. All were prospective studies, so treatment was given in a study setting.
Skin tone or phototype: Fitzpatrick skin types were listed study by study and spanned types I to VI, most often types II to V. Several studies did not record skin type.
Race: Not reported
Ethnicity: Not reported
Body sites: For narrowband UVB, face and neck, trunk, extremities, and hands and feet were pooled separately after at least 6 months. PUVA was not pooled by body site, because too few of the studies reported it.

What that means for this page: These are arithmetic complements of pooled group averages, not a second pooling. The studies were published up to January 2016. The review kept people who stopped early where it could, and otherwise counted the group at final assessment. So a pooled figure is not guaranteed to hold everyone enrolled. The single-arm pooling had no untreated comparison. The review does not report how many people worsened. None of this predicts one person or one patch.

Maintenance means continuing some treatment after a response settles, to try to hold the result. After a plateau, a prescriber may continue, taper, pause, or stop the course. That decision belongs to your prescriber, working from your record and current guidance.

Age range: Not reported
Condition subtype: Not reported
Severity or extent: Not reported
Sample size: Not reported
Geography and care setting: The narrowband UVB guideline is written for UK phototherapy services, in clinic and at home. The Task Force statement is a worldwide expert position for primary and specialist care. Neither reports a study population of its own.
Skin tone or phototype: Not reported
Race: Not reported
Ethnicity: Not reported
Body sites: The narrowband UVB guideline notes that likely response varies by site, giving the face and trunk against the hands and feet as the example. Neither document reports a patient group for this plan-review point.

What that means for this page: These are consensus guidance documents, not a study of one group of people. They ask the prescribing team to review the response so far, from photographs and the person’s record, and to weigh the risks and burden of a longer course. The Task Force adds that evidence for narrowband UVB as a maintenance treatment is limited. They set no schedule or dose and estimate no outcome or risk for any one person.

Narrowband UVB can cause erythema, including painful sunburn-type reactions, and requires a defined reaction and contact plan.

Age range: Not reported
Condition subtype: Not reported
Severity or extent: Not reported
Sample size: Not reported
Geography and care setting: Not reported
Skin tone or phototype: Not reported
Race: Not reported
Ethnicity: Not reported
Body sites: Not reported

What that means for this page: The cited guidance establishes a general safety boundary. It does not quantify risk or establish that every age, condition, care setting, skin tone, or body site is represented.

Evidence behind this page

Sources

Each evidence badge opens the source and its limits. The full list stays available here.

Phothera Product Manuals (opens in a new tab)
Phothera PhototherapyManufacturer document · Manufacturer, tier 4Independence not established
Published
Mar 3, 2026
SteadySkin last checked
Jul 31, 2026
What this source can and cannot tell you
What this source supports
Supports the current first-party route to Phothera device and accessory manuals and shows that instructions are model- and controller-specific.
What it does not support
It does not establish clinical suitability, comparative benefit, the condition of an individual unit, or that one manual applies to a related or legacy model; each exact linked manual and revision still requires verification.
Claim-specific review for this source is still in progress. Only the source-level evidence and limits are shown here.
Solarc/SolRx E-Series UVB Phototherapy System User’s Manual, revision 5.4A (opens in a new tab)
Solarc Systems Inc.Manufacturer document · Manufacturer, tier 4Independence not established
Published
Sep 18, 2020
SteadySkin last checked
Aug 22, 2026
What this source can and cannot tell you
What this source supports
Supports one page of the named SolRx E-Series manual revision, its specifications page. That page carries the models covered, the narrowband waveband, the bulb type and count, the nominal irradiance figures with their stated caution, and the per-device electrical and fuse ratings. It does not support another SolRx family, confirm that this is the newest revision for an individual unit, establish clinical suitability, or prove comparative safety or effectiveness; the owner must verify the exact current manual with Solarc.
What it does not support
The linked file is that one page, not the whole manual. It does not carry the installation, protective-equipment, maintenance or support sections that the rest of the manual holds.
Claim-specific review for this source is still in progress. Only the source-level evidence and limits are shown here.
Zerigo Health Terms of Use (opens in a new tab)
Zerigo Health, Inc.Manufacturer document · Manufacturer, tier 4Independence not established
Published
Mar 6, 2026
SteadySkin last checked
Jul 31, 2026
What this source can and cannot tell you
What this source supports
Supports Zerigo’s current first-party description of its United States prescription device, required mobile application, Member Guide, Care Guide support, data-enabled service model, transfer restrictions, and distinction between technical support and medical advice.
What it does not support
It does not independently establish comparative benefit, coverage, privacy quality, clinical suitability, or that the program terms will remain unchanged.
Claim-specific review for this source is still in progress. Only the source-level evidence and limits are shown here.
Reporting Serious Problems to FDA (opens in a new tab)
U.S. Food and Drug AdministrationRegulatory · Regulatory / guideline, tier 1Independent source
Published
Jul 31, 2026
SteadySkin last checked
Jul 31, 2026
What this source can and cannot tell you
What this source supports
Supports that patients, consumers, and health professionals can use FDA MedWatch to report serious reactions, product-quality problems, product-use errors, and other serious problems involving human medical products, including medical devices.
What it does not support
It does not determine whether a report is required, prove causation, replace clinical care, or replace the manufacturer’s equipment-support route.
Claim-specific review for this source is still in progress. Only the source-level evidence and limits are shown here.
Efficacy and safety of the oral Janus kinase 1 inhibitor povorcitinib in patients with extensive vitiligo in a phase 2, randomized, double-blinded, dose-ranging, placebo-controlled study (opens in a new tab)
Journal of the American Academy of Dermatology (Pandya AG, et al.)Randomized trial · Clinical research, tier 2Relevant relationship disclosed
Published
Oct 1, 2025
SteadySkin last checked
Aug 15, 2026
What this source can and cannot tell you
Why the independence label says this: Incyte sponsored the study; several authors were Incyte employees or shareholders, and other authors disclosed company relationships.
What this source supports
Supports the randomized phase 2 design, 171 adults with extensive nonsegmental vitiligo, group-level total-body outcome, continued improvement in the extension, reported study safety and the explicit limitation of limited demographic diversity.
What it does not support
The sponsor-linked trial does not establish approval, direct superiority over another treatment, every body-site outcome, a full commercial-product safety profile, long-term safety or an individual result.
Claim-specific review for this source is still in progress. Only the source-level evidence and limits are shown here.
Post hoc subgroup and body region analyses of VASI outcomes among patients with vitiligo in a phase 2 povorcitinib trial (opens in a new tab)
Advances in Therapy (Passeron T, et al.)Observational study · Supporting research, tier 3Relevant relationship disclosed
Published
Jul 13, 2026
SteadySkin last checked
Aug 16, 2026
What this source can and cannot tell you
Why the independence label says this: Incyte sponsored the underlying study; several authors were Incyte employees or shareholders and other authors disclosed company relationships.
What this source supports
Supports a descriptive post hoc analysis of 103 extension-evaluable adults who received povorcitinib throughout the phase 2 study, including subgroup reporting and week-52 VASI50 response proportions ranging from 25.8% for feet to 57.3% for head and neck outside the face.
What it does not support
The small pooled extension analysis was post hoc, descriptive and lacked a placebo comparator at week 52. It does not establish a reliable individual body-site prediction, phase 3 subgroup results, comparative superiority, approval, long-term safety or a personal treatment plan.
Claim-specific review for this source is still in progress. Only the source-level evidence and limits are shown here.
A study to evaluate efficacy and safety of povorcitinib in participants with nonsegmental vitiligo (STOP-V1) (opens in a new tab)
ClinicalTrials.gov, U.S. National Library of MedicineTrial registry · Supporting research, tier 3Relevant relationship disclosed
Published
Nov 2, 2023
SteadySkin last checked
Aug 15, 2026
What this source can and cannot tell you
Why the independence label says this: ClinicalTrials.gov hosts the record, while Incyte sponsors the study and supplies the registered information.
What this source supports
Supports the adult randomized phase 3 design, nonsegmental-vitiligo eligibility, 467-person enrollment record, study status, registered facial outcome and absence of posted result tables when reviewed.
What it does not support
Registration is not peer review, a regulatory decision, a published benefit-risk conclusion or a personal treatment plan.
Claim-specific review for this source is still in progress. Only the source-level evidence and limits are shown here.
A study to evaluate efficacy and safety of povorcitinib in participants with nonsegmental vitiligo (STOP-V2) (opens in a new tab)
ClinicalTrials.gov, U.S. National Library of MedicineTrial registry · Supporting research, tier 3Relevant relationship disclosed
Published
Nov 2, 2023
SteadySkin last checked
Aug 15, 2026
What this source can and cannot tell you
Why the independence label says this: ClinicalTrials.gov hosts the record, while Incyte sponsors the study and supplies the registered information.
What this source supports
Supports the adult randomized phase 3 design, nonsegmental-vitiligo eligibility, 450-person enrollment record, study status, registered facial outcome and absence of posted result tables when reviewed.
What it does not support
Registration is not peer review, a regulatory decision, a published benefit-risk conclusion or a personal treatment plan.
Claim-specific review for this source is still in progress. Only the source-level evidence and limits are shown here.
First-quarter 2026 povorcitinib vitiligo Phase 3 topline update (opens in a new tab)
Incyte CorporationManufacturer document · Manufacturer, tier 4Relevant relationship disclosed
Published
Apr 28, 2026
SteadySkin last checked
Aug 15, 2026
What this source can and cannot tell you
Why the independence label says this: Incyte develops povorcitinib, sponsored the studies, analyzed the results and issued the topline update before full peer-reviewed results were available.
What this source supports
Supports only Incyte’s report that STOP-V1 and STOP-V2 met the facial endpoint, the stated absolute response percentages, selected topline safety language and planned future vitiligo regulatory filings.
What it does not support
The update is not peer-reviewed publication, a regulator decision, proof of availability, direct comparison with another treatment, a complete safety profile or an individual prediction.
Claim-specific review for this source is still in progress. Only the source-level evidence and limits are shown here.
Protopic (tacrolimus) ointment: US prescribing information and Medication Guide (opens in a new tab)
DailyMed, U.S. National Library of MedicineRegulatory · Regulatory / guideline, tier 1Relevant relationship disclosed
Published
Jan 28, 2026
SteadySkin last checked
Aug 7, 2026
What this source can and cannot tell you
Why the independence label says this: The National Library of Medicine hosts DailyMed. The product company submits the label to FDA, so it is authoritative for product labeling but not independent efficacy evidence.
What this source supports
It establishes the US atopic-dermatitis indication, boxed warning, local effects, long-term-use precaution, and ultraviolet instructions for this product.
What it does not support
It does not approve tacrolimus for vitiligo, establish vitiligo efficacy, or resolve off-label guideline discussion of supervised combinations.
Claim-specific review for this source is still in progress. Only the source-level evidence and limits are shown here.
Elidel (pimecrolimus) cream: US prescribing information and Medication Guide (opens in a new tab)
DailyMed, U.S. National Library of MedicineRegulatory · Regulatory / guideline, tier 1Relevant relationship disclosed
Published
Apr 30, 2026
SteadySkin last checked
Aug 7, 2026
What this source can and cannot tell you
Why the independence label says this: The National Library of Medicine hosts DailyMed. The product company submits the label to FDA, so it is authoritative for product labeling but not independent efficacy evidence.
What this source supports
Supports the US atopic-dermatitis indication, boxed warning, application-site effects, long-term-use precaution and instructions to avoid ultraviolet treatment and minimize natural or artificial sunlight.
What it does not support
It does not approve pimecrolimus for vitiligo, establish vitiligo efficacy or resolve off-label guideline discussion of supervised combinations.
Claim-specific review for this source is still in progress. Only the source-level evidence and limits are shown here.
Phototherapy for Vitiligo: A Systematic Review and Meta-analysis (opens in a new tab)
JAMA Dermatology (Bae JM, et al.)Systematic review · Clinical research, tier 2Independent source
Published
Mar 29, 2017
SteadySkin last checked
Sep 3, 2026
What this source can and cannot tell you
What this source supports
Supports the separate pooled repigmentation rates and participant counts the review reports for narrowband UVB and PUVA at 3, 6 and 12 months, and the narrowband UVB rates pooled by body region after at least 6 months. Each pooled figure rests on the subset of studies that reported that measure at that time, not on the full review. It also supports plainly labelled arithmetic complements of those reported rates.
What it does not support
The pooled arms are single-group, so they describe what happened to those groups, not what the light caused. The review planned an intention-to-treat count and kept people who stopped early where it could; otherwise it used the group described at the final assessment, so no pooled figure is guaranteed to cover every enrolled participant. It does not report how many people worsened during treatment, does not predict an individual course, and sets no device, schedule or dose.
Claim-specific review for this source is still in progress. Only the source-level evidence and limits are shown here.
Psoriasis: assessment and management - recommendations (opens in a new tab)
National Institute for Health and Care ExcellenceGuideline · Regulatory / guideline, tier 1Independent source
Published
Oct 24, 2012
SteadySkin last checked
Aug 14, 2026
What this source can and cannot tell you
What this source supports
Supports psoriasis assessment across skin, nails, high-impact sites, life impact and joint concerns; same-day specialist assessment for generalised pustular psoriasis or erythroderma; and a treatment map that includes topical, phototherapy and systemic options.
What it does not support
It is UK guidance and does not diagnose a reader, create a US treatment sequence, determine personal urgency from a description, or establish current US labeling or coverage.
Claim-specific review for this source is still in progress. Only the source-level evidence and limits are shown here.
ICOTYDE (icotrokinra) tablets, for oral use - prescribing information revised March 2026 (opens in a new tab)
U.S. Food and Drug AdministrationRegulatory · Regulatory / guideline, tier 1Independence not established
Published
Mar 1, 2026
SteadySkin last checked
Sep 4, 2026
What this source can and cannot tell you
Why the independence label says this: FDA-approved prescribing information is authoritative for US labeling; it is product-specific regulator-approved labeling, not independent comparative clinical evidence.
What this source supports
Supports the current FDA-approved labeled plaque-psoriasis population, oral route, IL-23 receptor mechanism, and label precautions for Icotyde (icotrokinra).
What it does not support
The label states only “Revised: 3/2026”; it does not establish an exact revision day or the approval-action date. It also does not establish comparative superiority, personal suitability, insurance coverage, mature postmarketing evidence, or a class-wide conclusion. SteadySkin does not reproduce its regimen.
Claim-specific review for this source is still in progress. Only the source-level evidence and limits are shown here.
Psoriasis clinical guideline: systemic non-biological therapies (opens in a new tab)
American Academy of DermatologyGuideline · Regulatory / guideline, tier 1Relevant relationship disclosed
Published
Sep 1, 2020
SteadySkin last checked
Sep 4, 2026
What this source can and cannot tell you
Why the independence label says this: The guideline reports author relationships; it is not independent comparative proof for an individual choice.
What this source supports
Supports that methotrexate, apremilast, cyclosporine and acitretin are established systemic nonbiologic options considered in psoriasis care.
What it does not support
It does not select, rank or prescribe an option for an individual reader.
Claim-specific review for this source is still in progress. Only the source-level evidence and limits are shown here.
Psoriasis: Diagnosis, Treatment, and Steps to Take (opens in a new tab)
National Institute of Arthritis and Musculoskeletal and Skin DiseasesPatient education · Patient education, tier 5Independent source
Published
Oct 1, 2023
SteadySkin last checked
Aug 6, 2026
What this source can and cannot tell you
What this source supports
Supports a broad patient-facing map of topical treatment, phototherapy, oral systemic treatment and biologic treatment.
What it does not support
It does not rank categories or choose treatment for a particular person.
Claim-specific review for this source is still in progress. Only the source-level evidence and limits are shown here.
Psoriatic Arthritis: Diagnosis, Treatment, and Steps to Take (opens in a new tab)
National Institute of Arthritis and Musculoskeletal and Skin DiseasesPatient education · Patient education, tier 5Independent source
Published
Aug 1, 2024
SteadySkin last checked
Aug 6, 2026
What this source can and cannot tell you
What this source supports
Supports bringing joint, tendon, swelling, stiffness and nail concerns to a clinician because diagnosis uses clinical assessment and may require further evaluation.
What it does not support
It is not an online screening result and cannot diagnose psoriatic arthritis from a checklist.
Claim-specific review for this source is still in progress. Only the source-level evidence and limits are shown here.
Worldwide expert recommendations for the diagnosis and management of vitiligo: International Vitiligo Task Force Part 1 (opens in a new tab)
Journal of the European Academy of Dermatology and VenereologyGuideline · Regulatory / guideline, tier 1Relevant relationship disclosed
Published
Sep 25, 2023
SteadySkin last checked
Aug 22, 2026
What this source can and cannot tell you
Why the independence label says this: The journal is the publisher. This label refers to extensive author relationships disclosed for the recommendation, not to the journal itself.
What this source supports
It supports current expert-consensus terminology, clinical assessment, disease-activity evaluation, treatment-goal discussion, and shared decision-making. Its modified assessment check list names where the patches are as a disease feature, and gives genital involvement as its own example. It records white hairs as an item of its own, apart from what the vitiligo has done in the past six months. Its classification table keeps mucosal vitiligo as a subtype, both across more than one site and at one site alone. It supports planning care around what is there to work with, and its example is hair that still has its color.
What it does not support
It is not independent comparative proof. It cannot diagnose a reader from a description or photograph. It gives no figure for genital involvement, and it does not name lichen sclerosus. It does not set out the Vitiligo European Task Force grading scale. It puts no figure on white hairs and predicts nothing for one person.
Claim-specific review for this source is still in progress. Only the source-level evidence and limits are shown here.
British Association of Dermatologists guidelines for the management of people with vitiligo 2021 (opens in a new tab)
British Journal of Dermatology (Eleftheriadou V, et al.)Guideline · Regulatory / guideline, tier 1Independent source
Published
Jan 1, 2022
SteadySkin last checked
Aug 22, 2026
What this source can and cannot tell you
What this source supports
Supports the clinical history and assessment domains, evaluation of associated autoimmune conditions, its recommendation for thyroid function and antithyroid antibody screening, current classification context, treatment-option map, psychosocial assessment, medical photography and the limits of pediatric evidence. Its classification table defines mucosal vitiligo as the oral or genital mucosae. One mucosal site alone is filed as undetermined or unclassified. Its differential diagnosis table lists genital or extragenital lichen sclerosus among the conditions that can be mistaken for vitiligo. That table also lists eczema, psoriasis, lichen planus, pityriasis alba and piebaldism. It calls autoimmunity a contributor to the pathogenesis of vitiligo. It reports an earlier review finding a possible negative impact on intimacy and sexual functioning. It tells clinicians to discuss the psychosocial impact of living with the condition.
What it does not support
It was designed for UK care and reviewed literature through May 2019; it does not establish a universal testing plan, prescribe an individual plan, or establish current US labeling or coverage. Its differential diagnosis table is a list, not a method a reader can apply to their own skin. It does not say how to tell any two of those conditions apart. It gives no figure for how often vitiligo affects genital skin.
Claim-specific review for this source is still in progress. Only the source-level evidence and limits are shown here.
British Association of Dermatologists and British Photodermatology Group guidelines for narrowband ultraviolet B phototherapy 2022 (opens in a new tab)
British Journal of Dermatology (Goulden V, et al.)Guideline · Regulatory / guideline, tier 1Independent source
Published
Sep 1, 2022
SteadySkin last checked
Aug 22, 2026
What this source can and cannot tell you
What this source supports
It supports that traditional NB-UVB fluorescent lamps emit a narrow UVB band peaking around 311 nanometres. It backs wearing UV-protective goggles and keeping UV scatter off people nearby. It records the consent form naming goggles and the same clothing at each session. It also covers clinical uses, how it compares with other light treatments, safety limits including sunburn-type reactions, and the added safeguards home phototherapy needs.
What it does not support
It does not provide a personal treatment plan, approve a particular home setup, or replace the instructions for your own device. SteadySkin never reproduces its treatment schedules.
Claim-specific review for this source is still in progress. Only the source-level evidence and limits are shown here.
Phototherapy - NB-UVB (patient information leaflet) (opens in a new tab)
British Association of DermatologistsPatient education · Patient education, tier 5Independent source
Published
Jun 1, 2022
SteadySkin last checked
Aug 21, 2026
What this source can and cannot tell you
What this source supports
It supports a plain-language explanation that NB-UVB uses a small part of the UVB spectrum, is used for conditions including psoriasis, eczema, and vitiligo, and is distinct from sunlight or a sunbed. It also supports what a unit asks of its own patients during a course. It asks them not to sunbathe or use a sunbed for the whole of it, and to reduce sun exposure so that skin does not burn. It asks them to report a medicine, a cream, or newly exposed skin such as a haircut. It asks them to arrive without perfume, deodorant, aftershave or other cosmetics, because some of those raise light sensitivity and can leave patchy discolouration for months. It carries the unit’s own account of repeated courses. It states that the full risk of narrowband UVB is not known, and that roughly one in ten people in the UK develop skin cancer. It states that a review becomes usual practice past a stated number of treatments, and that many treatments can bring the wrinkling and discolouration of photoageing.
What it does not support
It is patient education, not primary evidence for an efficacy claim. Its printed next review date was June 2025 and it has not been updated since June 2022. It is therefore used only for what it plainly states, and never as current guidance. It is written for a UK hospital unit whose nurses examine skin at every visit, so it sets no rule for a device used at home. Its numbers stay in this record rather than in the copy. Those are the sun protection factor and star rating it names, the hours it names, the treatment count that triggers a review, and the multiple by which it estimates lifetime risk. That multiple is stated there as an assumption that narrowband UVB behaves like sunlight, not as a measurement.
Claim-specific review for this source is still in progress. Only the source-level evidence and limits are shown here.

Questions to carry into the conversation

How similar is the studied population to the question we are discussing?
Which missing population detail matters most for interpreting this claim?
Are we applying evidence beyond the condition, setting, or body sites studied?

How to use this page

Confidence and limits

Who was studied?

Bring your medicine list and ask how infections, vaccines, pregnancy or pregnancy plans, other health conditions and prior treatment reactions change the options. Each medicine has product-specific limits and monitoring rather than one class-wide checklist.

Generalized pustular psoriasis and erythroderma require same-day specialist assessment. Seek urgent clinical help for a sudden widespread pustular eruption or extensive, rapidly spreading redness. Feeling acutely unwell increases the urgency, but do not wait for fever or other systemic symptoms.

Medical phototherapy can treat psoriasis in the skin. It does not treat joint inflammation and is not a treatment for psoriatic arthritis. Joint concerns need a separate clinical assessment.

No. A commercial tanning device and prescribed narrowband UVB are not interchangeable. A tanning booth is not a shortcut around a medical light-treatment plan.

Use these questions to prepare, observe, record, and report. Your prescriber decides whether to start, continue, change, pause, or restart treatment, and the current instructions for your exact device govern its operation.

Guidelines describe reviewing the diagnosis and how it appears, current medicines, sensitivity to light, skin-cancer history, prior ultraviolet treatment, pregnancy, and other individual risks. Use this as a conversation starter - not as a self-test that says NB-UVB is or is not safe for you.

Several common medicine groups can make skin react more strongly to ultraviolet light. Your prescriber reviews everything you take before and during treatment. Bring the complete list, and do not stop or change anything on your own.

Use only the eye protection approved for your exact device or by your phototherapy team. Keep it on unless that team gives you a specific plan for treating the eyelids.

Yes. Using the same kind of equipment does not make the reasons for treatment, alternatives, or monitoring identical across conditions. Vitiligo decisions should use vitiligo guidance as well as phototherapy guidance. Use psoriasis-specific guidance for psoriasis decisions.

Stop and use the manufacturer’s official support route rather than testing, opening, bypassing, or repairing the device yourself. If you are in the United States, use the FDA route when a medical-device problem should also be reported to the regulator.

Maintenance means continuing some treatment after a response settles, to try to hold the result. After a plateau, a prescriber may continue, taper, pause, or stop the course. That decision belongs to your prescriber, working from your record and current guidance.

Narrowband UVB can cause erythema, including painful sunburn-type reactions, and requires a defined reaction and contact plan.

Sources

What this source supports

What it does not support

What this source supports

What it does not support

What this source supports

What it does not support

What this source supports

What it does not support

What this source supports

What it does not support

What this source supports

What it does not support

What this source supports

What it does not support

What this source supports

What it does not support

What this source supports

What it does not support

What this source supports

What it does not support

What this source supports

What it does not support

What this source supports

What it does not support

What this source supports

What it does not support

What this source supports

What it does not support

What this source supports

What it does not support

What this source supports

What it does not support

What this source supports

What it does not support

What this source supports

What it does not support

What this source supports

What it does not support

What this source supports

What it does not support

What this source supports

What it does not support

Questions to carry into the conversation