Phototherapy or light therapy is a prescription treatment that is typically prescribed by a dermatologist. Phototherapy involves exposing the skin to ultraviolet light on a regular basis and under medical supervision. Treatments are done in a doctor's office or psoriasis clinic or at home with a phototherapy unit. The key to success with light therapy is consistency.

Find a provider who offers phototherapy in our Health Care Provider Directory »

Learn more about phototherapy by contacting our Patient Navigation Center »

Learn about different types of light therapy:

Ultraviolet light B (UVB)

UVB phototherapy

Ultraviolet B, which is present in natural sunlight, is an effective treatment for psoriasis. UVB penetrates the skin and slows the growth of affected skin cells. Treatment involves exposing the skin to an artificial UVB light source for a set length of time on a regular schedule. This treatment is administered in a doctor's office or clinic or at home with a phototherapy unit.

There are two types of UVB treatment: broad band and narrow band. The main difference between them:

  • Narrow-band UVB light bulbs release a smaller range of ultraviolet light.
  • Narrow-band UVB may clear psoriasis faster and produce longer remissions.
  • Narrow-band UVB may require fewer treatments per week.

UVB treatment is offered in different ways. This can include small units for localized areas such as the hands and feet, full-body units or hand-held units. Some UVB units use traditional UV lamps or bulbs, and others use LED bulbs. 

Home UVB phototherapy

Treating psoriasis with a UVB light unit at home can be an economical and convenient choice. Like phototherapy in a doctor's office or clinic, it requires a consistent treatment schedule. Individuals are treated initially at a medical facility and then begin using a light unit at home.

It is critical when doing phototherapy at home to follow a doctor's instructions and continue with regular check-ups.

All phototherapy treatments, including purchase of equipment for home use, require a prescription. 

Excimer laser

The excimer laser, approved by the Food and Drug Administration (FDA) for treating chronic, localized psoriasis plaques, emits a high-intensity beam of ultraviolet light B (UVB).

The excimer laser can target areas of the skin affected by mild-to-moderate psoriasis. Research indicates it is a particularly effective treatment for scalp psoriasis. However, there is not yet enough long-term data to indicate how long improvements will last following a course of laser therapy.


Although both UVB and ultraviolet light A (UVA) are found in sunlight, UVB works best for psoriasis. UVB from the sun works the same way as UVB in phototherapy treatments.

However, using sunlight to treat psoriasis is not recommended for everyone. Sunlight is not as effective for the treatment of psoriasis as prescription phototherapy. Talk with your doctor to find out if treating with sunlight is right for you. 

Note: Some topical medications can increase the risk of sunburn. These include tazarotene, coal tar, Elidel (pimecrolimus) and Protopic (tacrolimus). Individuals using these products should talk with a doctor before going out in the sun.

People who are using PUVA (see below) or other forms of light therapy should limit or avoid exposure to natural sunlight unless directed by a doctor.

Psoralen + UVA (PUVA)

UVA is relatively ineffective for psoriasis unless it's used with the light-sensitizing medication psoralen. This process, called PUVA, slows down excessive skin cell growth and can clear psoriasis symptoms for varying periods of time. Stable plaque psoriasis, guttate psoriasis, and psoriasis of the palms and soles are most responsive to PUVA treatment.

Tanning beds

Some people visit tanning salons as an alternative to natural sunlight. Tanning beds in commercial salons emit mostly UVA light, not UVB. The beneficial effect for psoriasis is attributed primarily to UVB light. NPF does not support the use of indoor tanning beds as a substitute for phototherapy performed with a prescription and under a doctor's supervision. Read more on NPF'S position on indoor tanning beds »

The American Academy of Dermatology, the U.S. Food and Drug Administration and the Centers for Disease Control and Prevention all discourage the use of tanning beds and sun lamps. Indoor tanning raises the risk of melanoma by 59 percent, according to the AAD and the World Health Organization. In May 2014, the FDA reclassified sunlamps (which are used in tanning beds and booths) from Class I (low risk) to Class II (moderate risk) products.

The ultraviolet radiation from these devices can damage the skin, cause premature aging and increase the risk of skin cancer.

Get the facts on phototherapy

NPF's fact sheet on phototherapy will help you get up to speed on the popular treatment option. 

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