Phototherapy for Psoriasis

Treatment Overview

Phototherapy is the use of ultraviolet (UV) light to slow the rapid growth of new skin cells. This is helpful in treating psoriasis, which causes skin cells to grow too rapidly. There are two types of ultraviolet (UV) light therapy:

Ultraviolet B (UVB)

• Exposure times start at 30 to 60 seconds when therapy begins. You are exposed to the light until it causes the skin to turn slightly pink. When the skin no longer turns pink in the 24 hours after a treatment, the exposure time is increased.
• Treatments are given several times a week until the psoriasis clears up.
• UVB light is used alone, with tar products (Goeckerman treatment), or with anthralin applied to the skin (Ingram regimen).

One phototherapy option includes the use of narrow-band UVB light. This exposes you to only the wavelengths of light that work for treating psoriasis. Broadband UVB therapy uses a wider range of wavelengths.

A laser treatment for psoriasis (excimer laser) also uses UVB light. Excimer laser works well for psoriasis that has been hard to treat on the elbows and knees.^{footnote 1}

Ultraviolet A (UVA)

• UVA penetrates deeper into the skin than UVB.
• Treatment with UVA typically takes 20 minutes for a session.
• UVA light used with psoralen drugs is called PUVA. With PUVA, the treatment time is greatly reduced, from 20 minutes to about 2 minutes.

Treatments with UVB and UVA

Phototherapy can be used alone or with medicines. UVB light therapy is used alone to treat severe psoriasis. Typically, when medicines for psoriasis are used with light therapy, you will use or take the medicine first. You may apply it to your skin, take it by mouth, or use it as bath salts in water. Then you will go into a booth and be exposed to the UV light. Using two kinds of treatment is called combination therapy. Three common combination therapies are:

• Psoralen and UVA light therapy (PUVA), which combines UVA exposure and a medicine (called a psoralen) that makes your skin more sensitive to light.
• The Ingram regimen, which combines anthralin, tar products, and UVB phototherapy.
• The Goeckerman treatment, a combination of tar products and UVB phototherapy.

Your body is exposed to UV light from banks of light tubes that give off either UVB or UVA light in a booth. Booths come in several designs. Some look like phone booths and you can stand in them. Others look like tanning beds and you can lie down during treatment. The booth will record the total amount of light you are exposed to.

In general, your entire body is exposed to the light. (If psoriasis affects only certain areas of your body, UV light may be directed at these selected areas only.) You will wear sunglasses that block UV light and goggles or a blindfold to protect your eyes from getting cataracts. Men may also need to shield their genitals to protect them from an increased risk of genital cancer.