Phototherapy (light therapy) is a type of psoriasis treatment that often uses ultraviolet (UV) light, which reduces inflammation and slows down the creation of skin cells.

light therapy for psoriasis

For some people, over-the-counter or prescription creams are enough to manage psoriasis. However, if your skin remains itchy, scaly, and red, you may want to consider trying phototherapy, also known as light therapy.

It’s also used for other skin conditions, such as eczema. However, it’s not as simple as just going out in the sun.

A variety of different types of UV light treatments exist, including the following main types.

If you’re ready to try phototherapy, consider which treatment will be best for you. A doctor may recommend combining UV therapy with a prescription cream.

Narrowband ultraviolet B (NB-UVB) is the most prevalent form of phototherapy. It can be used to treat plaque psoriasis, which is the most common type of psoriasis, and guttate psoriasis.

NB-UVB lamps and light bulbs emit wavelengths of light between 311 and 313 nanometers (nm). Your starting dose will depend on your skin type and how easily you burn or tan.

NB-UVB light therapy is most effective when performed two or three times a week. Once the skin is clear, maintenance sessions can be performed on a weekly basis.

A 2017 study showed that around 75% of people receiving NB-UVB treatments found it cleared their psoriasis or led to minimal symptoms. They also used fewer prescription creams for their condition.

NB-UVB treatments may prove more effective when combined with topical treatments, such as vitamin D analogs and corticosteroids.

Broadband ultraviolet B (BB-UVB) light therapy is an older form than NB-UVB. The two treatments are similar.

However, BB-UVB lamps and light bulbs emit wavelengths of light between 270 and 390 nm. As with NB-UVB, your starting dose will depend on your skin type.

BB-UVB is considered less effective than NB-UVB. It should be reserved for instances where NB-UVB is not a treatment option.

It can be prescribed as a monotherapy or alongside retinoid acitretin (Soriatane). In combination therapy, the skin clears up faster, and lower doses of UVB can be used.

Targeted ultraviolet B (UVB) light therapy is applied to small areas of the body. It often involves the use of an excimer laser, excimer light, or NB-UVB light.

If you have psoriasis over less than 10% of your body (known as localized psoriasis), this treatment might work for you.

This approach exposes you to fewer UV rays overall, which can help reduce side effects and health risks. It also can result in faster clearing of the skin.

For best results, it should be performed two to three times a week.

This approach uses ultraviolet A (UVA) light with psoralen, a medication that increases your sensitivity to light. Psoralen can be:

  • taken orally
  • mixed in bathwater
  • applied topically

In general, PUVA is highly effective but not widely used or available.

Oral PUVA comes with the highest risk of drug interactions and side effects (such as nausea). It’s most effective when combined with an oral retinoid.

Bath PUVA is another option, though it may be less effective than oral PUVA, according to recent research.

Did you know?

Certain phototherapy types are considered safe for children and people who are pregnant. That said, NB-UVB can cause changes in the levels of folate in the blood.

PUVA is also generally not recommended during pregnancy, even though there’s no direct evidence of harm to the fetus. There’s also conflicting evidence on the safety of PUVA for children.

How much phototherapy you need and on what parts of your body depends on the extent of your psoriasis and where the impact is focused.

You may need the procedure to target just some areas or your full body. The technician will make sure you cover any sensitive areas before the procedure.

They may tell you ahead of time to avoid applying salicylic acid before your appointment, as this can decrease the effectiveness.

If you’re going to have UVA, you may need to apply psoralen before the procedure. Typically, people have a few sessions a week for 1–3 months, but this can vary from person to person.

Does insurance cover phototherapy?

According to CostHelper, an at-home phototherapy unit can typically cost $2,000–$6,000 or more.

Medicare — as well as many private insurance policies — often cover in-office treatment, though this may depend on your specific provider.

Home therapy

Home NB-UVB phototherapy is recommended as an alternative to in-office NB-UVB phototherapy for certain people with plaque psoriasis. It can be used for mild, moderate, or severe disease.

Many people who use phototherapy as a long-term treatment like the ease of having the treatment at home.

For the best results, you should undergo at least 20 phototherapy sessions, according to a 2016 study.

PUVA is the most effective of the major forms of phototherapy for treating psoriasis, according to 2019 treatment guidelines from the American Academy of Dermatology (AAD) and the National Psoriasis Foundation (NPF).

The next most effective phototherapy treatments are NB-UVB, followed by targeted UVB therapy and BB-UVB.

Although PUVA is more effective overall, NB-UVB is more often recommended by dermatologists because it’s less expensive, easier to use, and causes fewer side effects. To boost its effectiveness, NB-UVB is often used with additional medications.

People with darker skin tones may need higher doses initially to see the same effectiveness.

Certain people should not try light therapy. This includes people with:

  • lupus or porphyria
  • a history of skin cancer
  • the skin condition xeroderma pigmentosum, which makes you very sensitive to sunlight

In addition, certain medications — including some antibiotics — make you sensitive to light, which can affect this treatment.

Phototherapy can:

  • make your skin sore and discolored
  • lead to freckles or early skin aging
  • leave blisters
  • change the pigment of your skin, which can be more prominent in people with darker skin

It may increase your chance of certain types of skin cancer, so a doctor will watch for warning signs during and after treatment.

What light is best for psoriasis?

Some studies have shown that over 70% of people who received oral psoralen plus ultraviolet A (PUVA) achieved a 75% improvement in the Psoriasis Area and Severity Index score.

About 75% of people receiving narrowband ultraviolet B (NB-UVB) treatments, the most common type of phototherapy, found it cleared their psoriasis or reduced the symptoms, according to another study published in 2017.

How long is a light therapy session for psoriasis?

While this may depend on the specific type of light therapy, generally, each session takes about 15 minutes.

If you’re interested in phototherapy as a treatment option, talk with a doctor to find out if you’re a good candidate.

It’s important that you discuss the risks and benefits with a doctor when deciding if the treatment is right for you.