Light therapy provides a type of medical treatment called “phototherapy.” It involves exposing the skin to wavelengths of ultraviolet light. Under the care of a dermatologist, phototherapy provides effective treatment for many people living with psoriasis. Some receive phototherapy to clear a stubborn patch of psoriasis on the scalp, feet, or hands. For others, phototherapy effectively treats the entire body.

What is UVB and how does it work

UVB and UVA are types of ultraviolet radiation. Present in natural sunlight, ultraviolet light B (UVB) is an effective treatment for psoriasis. UVB penetrates the skin and slows the rapid growth of skin cells associated with psoriasis. Treatment involves exposing the skin to an artificial UVB light source for a set length of time on a regular schedule.

Who is a candidate for UVB?

Both adults and children can benefit from UVB treatment. It is effective in treating psoriasis for at least two-thirds of patients who meet these conditions:

  • Thin plaques (minimal scale buildup)
  • Moderate to severe disease (involving more than 3 percent of the skin)
  • Responsive to natural sunlight (most people are)

A treatment program may include medicines applied to the skin or taken by mouth, as well as UVB. Topical medicines, such as anthralin, coal tar, calcipotriene (brand name Dovonex) and tazarotene (brand name Tazorac) are effective along with UVB in some people. Using systemic drugs such as methotrexate, biologics and acitretin (brand name Soriatane) with UVB may also improve the effectiveness of the treatment.

How is UVB administered?

Usually, the patient undresses to expose all affected areas to the ultraviolet light. He or she then stands in a treatment booth lined with UVB lamps. Some doctors also have small units for treating areas such as the palms and soles.

A person will generally receive treatments three times per week. It takes an average of 30 treatments to reach maximum improvement of psoriasis lesions. The first exposure to the light is usually quite short, lasting as little as a few seconds. Exposure time depends on the person’s skin type and the intensity of the light emitted from the bulbs.

Since people with lighter skin easily, they start with shorter exposure times than people with darker skin. If there is no itching and/or tenderness from the previous session, the next treatment will be longer. Administering UVB light is not an exact science. Each person’s reaction to the light is not completely predictable.

UVB requires a significant time commitment. Individuals get the best results when they receive the regular follow-up treatments and strictly adhere to the action plan they make with their doctor.