Light Therapy for Psoriasis: How It Works and What to Expect

Psoriasis is a chronic, immune‑mediated skin disease that causes scaly plaques, redness and itching. For many people living with psoriasis, treatment begins with creams, ointments, shampoos and hope.
At first, topical treatments may help calm flare-ups. But over time, many patients find themselves facing familiar frustrations: symptoms returning quickly, messy daily routines, irritation, limited relief despite effort and consistency. That moment can feel discouraging.
If creams are no longer enough, what comes next?
At that stage, dermatologists often recommend an established and medically trusted next step: phototherapy (light therapy) — a treatment used in dermatology for decades to help control psoriasis safely and effectively.

What is light therapy?

Light therapy, also known as phototherapy, is the medical use of ultraviolet (UV) light to treat psoriasis and certain other inflammatory skin conditions. It has been an established medical treatment for decades.
It works by exposing the skin to carefully measured, controlled doses of specific therapeutic wavelengths of ultraviolet light that help slow the excessive skin cell turnover seen in psoriasis and calm overactive immune activity within the skin. In practical terms, this can mean:

• flatter plaques

• less redness

• reduced scaling

• less itch

• clearer skin over time

Ultraviolet radiation helps modulate the skin’s immune response directly at the source, targeting the underlying inflammatory processes that drive psoriasis rather than only treating surface symptoms. It helps by:

• Switching off overactive immune cells. In conditions such as psoriasis, certain immune cells (T-cells) become overactive and drive persistent inflammation. UV helps suppress or remove overactive immune cells in the skin and reduce the inflammatory signals they produce, reducing the core drivers of disease activity.

• Reducing inflammatory signals. UV lowers the expression of adhesion molecules such as ICAM-1, which act like “anchors” allowing inflammatory cells to accumulate in the skin. By reducing this adhesion, inflammation is calmed at its source.

• Promoting anti-inflammatory messengers. UV stimulates the release of anti-inflammatory mediators, including interleukin-10 (IL-10), helping suppress excessive immune responses and reduce flare-ups.

• Triggering melanogenesis and vitamin D synthesis: UVA and UVB light stimulate melanin production, which absorbs excess UV, and enhance vitamin D synthesis, both of which may improve skin barrier function.

The forms of medical phototherapy are:

• Narrow‑band ultraviolet‑B (NB‑UVB): NB-UVB is now the most commonly used phototherapy for psoriasis. It uses a specific therapeutic range of ultraviolet light, peaking at around 311, shown to be highly effective for managing psoriasis symptoms.

• Psoralen plus ultraviolet‑A (PUVA): Patients ingest or topically apply a photosensitising drug called psoralen and then expose the skin to UVA (320–400 nm). The psoralen makes skin cells more sensitive to UVA, enhancing its anti‑psoriatic effect.

• Excimer Therapy. A 308 nm excimer laser delivers high‑intensity NB‑UVB light to plaques. Because of its strength, it should be performed in clinics and is not suitable for home use.

It is also important to distinguish medical phototherapy from commercial sunbeds (tanning beds), as they are often confused. Sunbeds mainly emit UVA light, which is not the same therapeutic treatment used in psoriasis care. They deliver uncontrolled doses, offer little proven benefit for psoriasis, and are associated with a greater long-term risk of skin cancer and premature skin ageing. For these reasons, they are not recommended by dermatologists.

Types of Machines for full‑body and localised psoriasis

Because psoriasis can affect anything from a few plaques to most of the skin surface, phototherapy machines come in a range of designs, making treatment highly versatile. Whole‑body cabins treat extensive disease, while partial body panels, hand‑held or comb‑like devices allow targeted treatment of localised plaques, the scalp, face or even nail psoriasis. 

• Cabin units for full‑body treatment – Hospital‑based phototherapy units use a stand‑in cabinet lined with six‑foot ultraviolet tubes. Patients stand in a light cabinet for a short session while the whole skin surface is treated. These cabinets are commonly used in hospitals or clinics and are ideal for extensive psoriasis covering large areas of the body.

• Partial Body Panels. Smaller machines target limited sites such as the hands or feet and other localised areas. These units contain a few bulbs and allow treatment of localised plaques without exposing the rest of the body.

• Handheld and comb‑like devices. Targeted phototherapy uses portable devices to deliver UV light directly to individual smaller plaques or targeted areas and difficult‑to‑treat regions like the scalp. Comb attachments help UV light penetrate through hair so that scalp psoriasis can be treated effectively. Their compact size makes them especially convenient for home use, allowing quick and comfortable treatment of psoriasis patches without the need to treat the whole body.

From Fluorescent Lamps to Modern LED Devices

For many years, medical phototherapy treatment relied mainly on fluorescent lamps, which helped build the strong evidence base behind UV treatment. Today, LED technology is also advancing in phototherapy—just as many people now recognise LED-based red light masks and skincare devices.
In certified UVB systems, LEDs can offer more consistent output, even light distribution through strategic positioning, and more compact, flexible device designs. Examples include UV Tactus, the first CE-certified NB UVB LED device in Europe, combining modern LED technology with established NB-UVB treatment principles.
When choosing any light-based treatment technology, it is important to use properly certified medical devices to help ensure both safety and effectiveness.
Home Devices. Home phototherapy devices are increasingly being recommended by dermatologists for selected patients, particularly where regular clinic attendance is difficult and when psoriasis is localised. Innovative devices are now emerging that add modern features such as dosing support, treatment tracking and guided treatment tools, helping improve safety, precision and a more comprehensive treatment experience at home.

Is Sunlight the Same as Phototherapy?

Not exactly. Many people with psoriasis notice their skin improves during summer or after sunny holidays, when more of the skin is naturally exposed to sunlight. That happens because sunlight contains ultraviolet (UV) light, that is proven to be very effective in treating psoriasis. However sunlight has clear limitations:

• not available consistently year-round or on demand

• cannot be precisely measured

• easy to overdo and burn (burn can activate a flare up)

Medical phototherapy treatment is very different from natural sun exposure. Using artificial light sources such as LED or fluorescent technology, therapeutic ultraviolet light is reproduced while focusing on the wavelengths proven to treat psoriasis and filtering out/avoiding harmful and ineffective sunlight rays. It is a structured treatment where the wavelength, dose, frequency and progress are carefully controlled, and it can be used reliably in any season.

Why Phototherapy Is Different

• Targeted Therapeutic Light. Phototherapy commonly uses narrowband UVB (around 311 nm), the wavelength shown to be especially effective for treating psoriasis and other inflammatory skin conditions. Natural sunlight contains only a small proportion of this therapeutic UVB, alongside other unnecessary wavelengths.

• Precise Dosing. Sunlight is unpredictable, as UV levels vary depending on the season, weather, time of day, latitude, altitude and other environmental factors. Medical phototherapy delivers a measured and stable dose designed to maximise benefit while reducing risk.

• Safer Progression. Treatment usually begins with a low dose, with the dose increased gradually according to the skin’s response, helping optimise results while keeping risk as low as possible — something natural sun exposure cannot reliably provide.

The bottom line is that phototherapy treatment uses the same beneficial principle—UV light—but in a measured, medically supervised and reliable format, while focusing on therapeutic wavelengths and minimising unnecessary exposure to less beneficial or harmful rays.

UVB vs PUVA Therapy: Types of Phototherapy Explained

Although both are forms of ultraviolet light, UVB and UVA act differently in the skin and are used differently in dermatology. Dermatologists choose the most suitable type depending on your psoriasis pattern, skin type, treatment history and goals.

Narrowband UVB phototherapy (NB-UVB) at 311 nm

• Mechanism: UVB works mainly in the more superficial layers of the skin, where psoriasis plaques develop. This makes it particularly effective for slowing excessive skin cell turnover and reducing inflammation directly in affected areas. UVB radiation penetrates the skin to induce apoptosis (cell death) of pathogenic T cells and keratinocytes, which are responsible for psoriasis inflammation. It works by suppressing inflammatory pathways, such as the Th17 and JAK/STAT pathways, and reducing proinflammatory cytokines like IL-17A and TNF-alpha.

• Usability: Narrow‑band UVB has become the first‑line phototherapy of choice because it can often match the efficacy of PUVA with fewer side effects.

PUVA Therapy (Photochemotherapy)

PUVA is a "second-line" therapy typically reserved for cases that do not respond to UVB.

• Mechanism: UVA penetrates deeper into the skin than UVB. On its own, it is generally less effective for psoriasis, which is why medical UVA treatment is usually combined with photosensitising medication called psoralen to make the skin more responsive. Psoralen can be taken orally, injected, or applied topically via a bath or cream. Psoralen molecules intercalate (insert) into the DNA of skin cells. When exposed to UVA light, these molecules form "monoadducts" that trigger apoptosis in overactive skin cells.

• Usability: Because UVA reaches deeper layers, it can be useful for certain skin diseases that involve deeper inflammation or thicker tissue changes. PUVA is highly effective for refractory (difficult to treat) psoriatic plaques and palmoplantar pustular psoriasis (psoriasis on the palms and soles).

Typical courses of NB UVB or PUVA usually involve treatment three times weekly for around 2-3 months. The starting dose is chosen based on skin type or light sensitivity, then gradually increased according to the treatment plan and the skin’s response.
Evidence from systematic reviews and randomised trials shows that both NB‑UVB and PUVA are effective, but their risk profiles and convenience differ.

Is Light Therapy Safe and Effective?

Phototherapy—especially narrowband UVB (NB-UVB)—is a highly effective, well-established and time-honoured treatment for severe and also mild to moderate psoriasis. In modern practice, it remains a cornerstone option for patients whose psoriasis is not adequately controlled with topical treatments, or for those who wish to avoid or delay systemic and biologic therapies.
In practical terms, phototherapy treatment may help lead to:

• thinner, calmer plaques

• significant reduction or clearance of redness and inflammation

• marked improvement or clearance of flaking and scaling

• reduced or eliminated itching and irritation

• clearer skin with continued treatment

Many patients experience significant improvement, and achieve clear or almost clear skin after a treatment course. The improvement may last weeks, months or sometimes years after you stop treatment. It is important to remember that results vary between individuals. Some people notice visible improvement earlier, while others require more sessions before meaningful changes appear. Consistency is one of the most important factors for success.

How Effective Are NB-UVB and PUVA?

• PASI 75 Achievement: Approximately 62% to 70.5% of patients undergoing Narrowband UVB (NB-UVB) achieve at least a 75% improvement in their Psoriasis Area and Severity Index (PASI 75).

• NB-UVB is the most commonly used form of phototherapy for psoriasis today and is highly effective for many patients. A meta‑analysis of 31 studies found that around 62% of patients achieved at least a 75% improvement in their Psoriasis Area and Severity Index (PASI 75) after NB‑UVB therapy. Another systematic review focusing on skin of colour reported even higher rates (70.5% reaching PASI 75). Overall clearance rates range from 60% to 70% after 20–36 treatments.

• PUVA is often regarded as a stronger option for severe, thicker or treatment-resistant psoriasis. Some trials found that PUVA achieved clearance in 84% of participants compared with 65% for NB‑UVB, and that remission at six months occurred in 68% of PUVA patients but only 35% of NB‑UVB patients. However, other studies report similar efficacy when NB‑UVB is delivered three times per week.

• Combination Therapy Benefits. Phototherapy is effective both as monotherapy (used on its own) and as part of combination treatment. It can deliver strong results alone, but in clinical practice dermatologists often combine it with topical therapies or selected systemic medicines including biologics, to enhance outcomes, speed clearance, or reduce the amount of medication or cumulative UV exposure required.

• Long-term Reliability: Unlike some other treatments, which can sometimes lead to a "secondary loss of response" over time, phototherapy remains consistently effective throughout repeated treatment cycles.

Possible Side Effects

While generally safe, light therapy does carry both short-term and long-term risks:

• Short-term Side Effects: Common reactions occurring within 24 hours of treatment include dryness, erythema (redness), edema, pruritus (itching), pain, and blistering. These short-term effects are usually managed by adjusting the dose and using emollients. Also mild tanning or darkening of treated skin can happen.

• Psoralen may cause nausea, headaches or gastrointestinal upset.

• Long-term Risks: cumulative exposure may contribute to photoaging over time.

• Type-Specific Risks: The risk of developing skin cancer is much higher and more persistent with PUVA therapy than with NB-UVB. In fact, the largest study to date on NB-UVB found no increased association with cancer.

Eye Protection. Protective eyewear is essential during treatment. This is particularly important with PUVA, where inadequate protection may increase the risk of cataracts.

Correct Dosing and Supervision

Phototherapy should be used consistently and according to established treatment protocols to achieve the best outcomes while maintaining safety. Results can appear at different speeds for different people, but regular sessions are often key to success.
An important part of these protocols is accurate dosing. Too little light may limit results, while too much can irritate or burn the skin. Treatment is therefore tailored according to factors such as skin type, body area treated, previous response, missed sessions, redness after treatment, and relevant medicines or medical history. The starting dose is usually cautious, then increased gradually according to the skin’s response.
Professional supervision helps improve safety, optimise results and identify contraindications. The same principles apply when treatment is used at home, so it is important to choose quality devices that support accurate dosing, safety and treatment tracking.
The Bottom Line. Psoriasis phototherapy is one of the most effective and established non-systemic psoriasis treatments available today. For many patients, it offers significant skin clearance, good long-term reliability, and a valuable alternative before escalating to systemic medication. When properly dosed and used consistently, it can be both safe and highly effective.

At‑home vs in‑clinic phototherapy

For many years, phototherapy was mainly associated with hospitals and dermatology clinics. Today, home phototherapy is gaining traction because it helps overcome many of the practical barriers that have historically limited clinic-based treatment, while modern technology has improved safety, convenience and confidence. Studies have found that, home UVB phototherapy can achieve outcomes comparable to clinic treatment, with similar side-effect profiles and high patient satisfaction.
Both approaches use the same therapeutic principle—controlled ultraviolet light—and generally follow the same treatment protocols and dosing principles, but differ in how treatment is accessed, supervised and managed.

In-Clinic Phototherapy

Clinic treatment offers direct professional supervision, with staff adjusting doses according to skin type and response. This remains an excellent option, particularly for widespread psoriasis or patients who prefer close monitoring. However, treatment often requires attendance 2–3 times per week for 2-3 months, which can be challenging because of:

• travel time

• parking or transport costs

• time off work

• childcare arrangements

• waiting lists in some areas

At-Home Phototherapy

Home treatment can make regular sessions more realistic by allowing patients to treat around daily life. This may improve consistency—which is important, as phototherapy works best when sessions are performed regularly.
It can also allow earlier treatment of localised flare-ups under an agreed plan, rather than waiting for appointments
For home phototherapy, it is extremely important to use only a properly certified medical device, such as one that is CE certified or MHRA listed, depending on the market.
Certified devices are designed to meet recognised safety, quality and performance standards, helping ensure accurate dosing and effective treatment. Uncertified products on the market may lack appropriate controls, consistency or regulatory oversight, which may create unnecessary safety risks and compromise treatment results.
Historically, some dermatologists were cautious about home phototherapy because of concerns around inaccurate dosing, burns, poor adherence, and the risk that patients might not fully understand or follow treatment protocols without proper training and ongoing guidance. Some modern devices have helped address many of these concerns through features such as:

• professional dosimeter with a real-time sensor for accurate dose measurement and reliable treatment delivery

• guided dosing support based on treatment schedules and skin response

• treatment logs to keep a clear record of sessions

• reminders to improve consistency

• progress tracking to monitor results over time

• smartphone apps that record each treatment and guide dosing

• comprehensive onboarding support including patient education and regular check‑ins, further enhance safety and ensure that home users understand how to adjust doses and recognise side‑effects. 

These advances have made home phototherapy more structured and user-friendly. Examples include medical phototherapy device such as UV Tactus, which combine LED-based targeted NB-UVB treatment with digital guidance tools and a professional dosimeter.
Home devices should be viewed as treatment options for suitable patients—not replacements for dermatologist care. Proper patient selection, initial screening and ongoing physician involvement remain essential.
Clinic phototherapy offers close supervision and remains highly valuable. Home phototherapy can offer greater convenience and accessibility for selected patients, especially for localised psoriasis or when regular clinic attendance is difficult. Home handheld devices can be particularly practical when psoriasis affects smaller but troublesome areas that still have a major impact on comfort or confidence such as elbows, knees, scalp psoriasis, hands and feet, hairline or scalp margins, isolated stubborn plaques. In both settings, correct dosing, adherence to protocol and ongoing medical guidance remain essential.
In many countries, in-clinic phototherapy is available through the public healthcare system and may be fully or partially reimbursed for a certain number of treatments. Home phototherapy, by contrast, is often paid for out of pocket, but is usually a one-time investment that can be used for many treatment courses over time. It may also reduce other ongoing costs such as travel, parking, time away from work, repeated spending on creams, and delays in accessing treatment when flare-ups occur.

Who Is a Good Candidate for Light Therapy?

Phototherapy is a highly effective and safe treatment option that can be used for different types of psoriasis, depending on the individual case. Its suitability depends on the type and extent of psoriasis, medical history, and treatment goals. It is often considered when patients:

• have not achieved sufficient improvement with topical creams, lotions or ointments

• have scalp psoriasis or difficult localised areas

• prefer a non-drug treatment option

• wish to avoid or delay systemic or biologic medicines

• have other health conditions that may make systemic drugs less suitable

• notice their skin reliably improves with sunlight

NB-UVB may be used across many age groups, including selected children and during pregnancy when clinically appropriate. Phototherapy can also be used in all skin tones, although dosing and monitoring may need to be adjusted individually.
Reasons why phototherapy may need to be avoided or used with caution include:

• Photosensitive conditions – such as lupus erythematosus, dermatomyositis, or skin diseases that worsen in natural sunlight.

• Rare genetic disorders with extreme UV sensitivity – such as xeroderma pigmentosum, Gorlin syndrome, or certain forms of albinism.

• Current medicines that increase risk – some medications can increase photosensitivity or suppress the immune system, including certain antibiotics, retinoids, ciclosporin, azathioprine, tacrolimus, and in some cases methotrexate depending on the clinical situation.

• Previous skin cancer history – melanoma or non-melanoma cancer may affect suitability.

• Strong family history of early skin cancer or previous exposure to arsenic or ionising radiation.

• Inability to follow treatment protocols safely – for example if regular monitoring or correct dosing may be difficult.

In some cases, phototherapy may still be possible with adjustments or closer supervision. For example, certain systemic medicines such as methotrexate, ciclosporin or retinoids may require dose changes, temporary interruption, or careful monitoring during treatment.
Ultimately, eligibility for phototherapy is determined by a consultant dermatologist following a detailed dermatological examination. The dermatologist will assess the extent of the skin lesions, evaluate any potential contraindications, and weigh the risk-benefit ratio based on the individual patient's diagnosis and medical history.

What to expect during treatment

A typical phototherapy course consists of three sessions per week for 20–36 sessions. Depending on the psoriasis pattern, treatment may involve the whole body or targeted areas using different machines such as walk-in cabins, panels or handheld devices. Key points include:

Before Each Session

Patients are usually advised to shower or ensure the skin is clean, avoid perfumes or irritating products, wear protective goggles, and avoid applying creams, ointments or moisturisers immediately before treatment unless specifically advised.

During Treatment

The starting dose is usually based on skin type or previous light sensitivity. Exposure then increases gradually according to the treatment protocol and the skin’s response.
Early sessions may last only seconds to a few minutes, while later sessions can become longer depending on the machine and area treated. During treatment, there are usually no unpleasant sensations or significant heat, as NB-UVB therapy is generally well tolerated.
A mild pinkness afterwards can occur and may indicate the need for dose adjustment.

Aftercare

After treatment, the skin may feel warm, dry or mildly sun-exposed. It is often recommended to apply moisturiser afterwards, continue regular emollient use, avoid additional UV exposure the same day, and avoid harsh products, hot showers or saunas if the skin feels irritated.

Monitoring Progress

Dermatologists usually review progress regularly and adjust dosing if needed. Once clearance is achieved, sessions may sometimes be reduced, spaced out or stopped until needed again. When treatment is used at home, patients also need to monitor their own skin response, follow dose-adjustment guidance, and contact their dermatologist if any adverse reactions occur. Ongoing reviews are important to assess progress, discuss maintenance strategies, and decide when further treatment is needed.
Phototherapy may be used as monotherapy (on its own) or in combination with moisturisers, selected creams, and—when advised by a dermatologist—alongside other psoriasis medications as part of a broader treatment plan.
Many people notice improvement after 6–10 sessions, but fuller results often take longer, with a typical course averaging around 30 sessions. Response varies between individuals, and even in the same person different body areas may improve at different speeds. Regular attendance, patience and following the treatment plan are key to success.
For phototherapy to be safe and effective, patients play an active role alongside their clinical team. It is important to monitor how the skin reacts in the 12–24 hours after each session, as redness often peaks during this period, and to report painful redness, tenderness or blistering before the next treatment so the dose can be adjusted.
Patients should also inform their medical team before starting any new medication, including herbal remedies, as some medicines can increase sensitivity to light. Following the treatment protocol carefully is essential, including consistent treatment setup and wearing protective goggles.
Especially with home phototherapy, accurate self-administration and clear record keeping are important. Treatment logs or dedicated apps can help track sessions, skin reactions, progress and missed treatments, while also supporting dose guidance and adherence to the treatment plan. Examples include systems such as UV Tactus, which combine home NB-UVB treatment with app-based treatment support.

Can Psoriasis Return After Light Therapy?

Yes. Like all current psoriasis treatments, phototherapy is not a permanent cure, as psoriasis is a chronic condition. Instead, it is commonly used in treatment courses designed to clear the skin, followed by periods of remission with no treatment.
Many patients enjoy several months of clearer skin after a successful course, and some may remain clear or significantly improved for a year or even longer.
An observational study reported that approximately 75% of patients achieved clear or minimal disease and used fewer topical medicines for at least 12 months after treatment.
Hand‑held devices and excimer lasers for localised plaques also appear to yield longer remission than topical therapy alone. 
However, flare-ups can return over time. Relapses are a normal part of the treatment cycle. Once your skin flares up again, you simply begin a new course of light therapy.
A Key Advantage of Phototherapy. A major benefit of phototherapy is that a secondary loss of response—where a treatment becomes less effective after long-term use, as can happen with some other treatment methods—does not appear to commonly occur. This means that even if you have many courses over several years, the light is likely to remain just as effective each time. This sustained responsiveness makes phototherapy a valuable option for chronic disease management.
Phototherapy is valued not only for clearance, but also for its potential to provide meaningful remission periods. Studies have shown that many patients remain improved for months after treatment. Some observational data have reported prolonged benefit and reduced need for topical medicines after NB-UVB courses.
Rapid Relapse: if psoriasis relapses very soon after a course, or responds poorly despite correct treatment, a dermatologist may reassess the plan and consider other options such as combination therapy or systemic treatment.

Maintenance Therapy

In selected patients—particularly those who relapse quickly—dermatologists may recommend maintenance treatment, where sessions continue at a lower frequency (for example weekly or fortnightly) after clearance. This may help prolong remission and act as a preventative strategy for some patients, particularly during more difficult seasonal periods or times of increased stress, although it is not necessary or beneficial for everyone.
Phototherapy is often combined with other treatments to improve results, speed clearance and may help prolong remission before psoriasis returns. This may include moisturisers, selected creams (such as steroid or vitamin D treatments), systemic medicines when advised by a dermatologist, or targeted devices for localised plaques and scalp psoriasis. Your dermatologist can advise which combinations are appropriate and when products should be used around treatment sessions.

Lifestyle Habits That May Help Prolong Remission

Maintaining healthy daily habits can also help support clearer skin after treatment. Regular use of moisturisers, gentle skincare, stress management, good sleep, a balanced diet, limiting alcohol, avoiding smoking, reducing personal triggers where possible, and following medical advice may help reduce flare-ups and prolong remission. In some cases, dermatologists may also combine phototherapy with selected medicines when clinically appropriate.

When to Talk to a Dermatologist

Consult a dermatologist if you have psoriasis—or suspect you may have it—and your current treatments are not working well enough, are causing side effects, or the condition is affecting your daily life. This is particularly important if plaques are widespread, worsening, or difficult to manage.
A dermatologist can confirm the diagnosis, assess whether phototherapy is appropriate, review other medical conditions or medications, and explain alternative options such as systemic treatments or biologics.
They can also compile an individual treatment plan, advising whether phototherapy should be used as monotherapy or combined with other treatments, while helping to guide dosing and monitor progress over time.
Always seek professional advice before starting phototherapy or if you experience side effects during treatment, as dosing should be tailored to the individual. Never attempt to replicate medical phototherapy with tanning beds or uncontrolled sun exposure, as these carry significant risks without the same therapeutic precision. For home treatment, use only properly certified medical devices.

Conclusion

Phototherapy remains one of the most established, effective and trusted treatments for psoriasis in modern dermatology. It is commonly considered the next step when topical creams are no longer enough, making it a usual second-line treatment pathway before or alongside systemic options for many patients. For many people, it offers the possibility of significant skin clearance, longer periods of remission, and a valuable non-drug medical option that can reduce reliance on continuous medication.
Importantly, phototherapy can be tailored to the extent and location of disease. Full-body cabins may be used for widespread psoriasis, while handheld devices, targeted units and comb attachments can be especially practical for localised plaques and scalp psoriasis.
Access to treatment is also evolving. New home medical devices, equipped with timers, professional dosimeters and app-based guidance, are helping to address historic concerns around dosing, safety and adherence. This is making high-quality home phototherapy increasingly realistic for suitable patients, particularly when regular clinic attendance is difficult.
While psoriasis can return after treatment—as it can with any current therapy—phototherapy remains a reliable option because repeat courses often continue to work well over time when properly supervised.
For patients who feel caught between creams that are no longer enough and stronger medicines they may not yet want or need, phototherapy can be an important middle path: evidence-based, time-tested, and now more accessible than ever.
The most important next step is to speak with a dermatologist, who can help determine whether phototherapy is suitable for your psoriasis and create a personalised treatment plan for safe and effective use.

Frequently asked questions (FAQ)

Do you need a prescription for phototherapy?

In many cases, phototherapy begins with a recommendation from a dermatologist or healthcare professional, who can confirm the diagnosis, assess whether treatment is appropriate, and advise on safe dosing.
For in-clinic phototherapy, a formal prescription or referral may be required, particularly where treatment is reimbursed through a healthcare system. At-home phototherapy devices may often be purchased without a prescription, depending on the country and supplier, but medical guidance is still strongly recommended to ensure safe and effective use.

How many sessions are required for UVB therapy?

This varies by condition, severity and individual response. For psoriasis, a typical NB-UVB course often involves around 20–36 sessions, usually given two to three times per week.
Many people begin to notice first improvements after 6–10 sessions, while fuller results usually take longer. Some body areas may also respond faster than others.

Can phototherapy cure psoriasis or just manage it?

Phototherapy does not cure psoriasis permanently, as psoriasis is a chronic condition. However, it can be a highly effective way to manage symptoms, clear plaques, and achieve periods of remission where the skin stays clear or greatly improved. Many people experience significant relief, and treatment can be repeated if psoriasis returns.

What are the risks and side effects of light therapy?

When properly supervised, medical light therapy—especially NB-UVB phototherapy—is generally safe and well tolerated. Most side effects are mild and temporary, and may include redness, dryness, itching, warmth, mild tenderness, mild burning if the dose is too strong, occasional blistering, or temporary tanning.
These effects are usually managed by adjusting the dose or treatment schedule. Because phototherapy uses ultraviolet light, long-term exposure is also considered, which is why treatment plans are medically monitored to limit cumulative UV dose and maintain safety. Very high lifetime exposure may contribute to skin ageing or pigment changes.
PUVA therapy is associated with a higher long-term skin cancer risk, whereas NB-UVB has not been consistently associated with an increased skin cancer risk when used appropriately under medical supervision.
NB-UVB has a strong safety profile when used correctly under professional guidance.

Can you do psoriasis light therapy at home?

Yes, selected patients may use prescription home phototherapy devices under dermatologist guidance. Research suggests that, when appropriately supervised, home UVB treatment can be comparable to clinic treatment for some patients.
Modern devices may include guided dosing, reminders and progress tracking to improve safety and consistency.