UVB phototherapy
What is UVB and how does it work?
Present in natural sunlight, ultraviolet light B (UVB) is an effective treatment for psoriasis. UVB penetrates the skin and slows the abnormally rapid growth of skin cells associated with psoriasis. UVB treatment involves exposing the skin to an artificial UVB light source for a set length of time on a regular schedule, either under a doctor's direction in a medical setting or with a home unit purchased with a doctor's prescription. (Click here to learn more about home phototherapy.)
There are two types of UVB treatment, broad band and narrow band. Broad-band UVB is primarily featured in this section because it is more commonly used in the United States; however, narrow-band UVB is similar in many ways and is becoming more widely used. The major difference between broad-band and narrow-band UVB is that narrow-band UVB units emit a more specific range of UV wavelengths.
Several studies indicate that narrow-band UVB clears psoriasis faster and produces longer remissions than broad-band UVB. Narrow-band UVB may be effective with fewer treatments per week than broad-band UVB. Narrow-band UVB is also emerging as an alternative to PUVA, the light-sensitizing medication psoralen plus exposure to ultraviolet light A. Although not as effective as PUVA, narrow-band UVB is easier for people to undergo and may be safer over the long term.
The use of narrow-band UVB may increase as doctors and patients learn more about its effectiveness and safety and as the equipment becomes less expensive.
Who is a candidate for UVB?
UVB treatment can be used by adults and children, and will be effective in treating psoriasis for at least two-thirds of patients who meet these criteria:
- Thin plaques (decreased scale build up)
- Moderate to severe disease (involving more than 3 percent of the skin)
- Responsive to natural sunlight
UVB may be used alone or in combination with topical treatments or systemic medications. Topical treatments, such as anthralin, coal tar and derivatives of vitamin D3 (Dovonex) and vitamin A (Tazorac), have been shown to be effective in conjunction with UVB in some patients. In addition, the combination of UVB with systemic treatments, including methotrexate, biologics and Soriatane, may improve the response to UVB.
How is UVB administered?
The patient stands in a treatment light box lined with UVB lamps, or an enclosure containing one or more columns of lamps. A person undresses to expose all affected areas to the ultraviolet light. Some doctors have small units for treating localized areas such as the palms and soles.
A patient generally will 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 (see table) and the intensity of the light emitted from the bulbs. People with lighter skin start with shorter exposure times than people with darker skin.
Normally, treatment times are gradually increased until clearing occurs, unless the last session produced itching and/or skin tenderness. Because administering UVB light is not an exact science, each person's reaction to the light is not completely predictable. Subsequent sessions of UVB are adjusted according to a person's individual response.
UVB requires a significant time commitment. People get the best results when they keep scheduled appointments and follow treatment directions carefully.
A doctor may require a patient to do one or more of the following before UVB treatments begin:
- Inform the medical staff of medications used, topically or internally;
- Soak in warm water for 30 minutes to remove psoriasis scales;
- Protect certain areas of skin (for example, the backs of hands, neck, lips, nipples and dark, pigmented areas of the breasts) with sunscreen;
- Cover uninvolved areas of the body, such as the face, with paper, cloth or sunscreen to shield from unwanted light exposure;
- Apply topical coal tar preparations to the lesions at night and wash them off in the morning before a UVB treatment.
Some studies suggest that mineral oil and petrolatum are as effective as coal tar or anthralin when used in conjunction with UVB. Applied in a thin layer before treatment, mineral oil or petrolatum can improve the ability of the light to penetrate the skin. However, anything that might enhance the penetration of light to the skin must be done gradually to avoid burning.
Any other topical application left on the skin may block some or all of the UVB light and reduce the effectiveness of the treatment. This is especially true of coal tar, salicylic acid and thick, white moisturizers. It is important for you to talk to your doctor about all moisturizers and topical medications that you are using to receive the maximum benefit from phototherapy treatment.
What happens once the skin clears?
Once the skin clears, the treatments can be stopped. They should be resumed as the lesions begin to reappear. Sometimes UVB is continued on a maintenance basis.
Studies show that UVB maintenance can increase remission time. Most people need about eight maintenance treatments per month to prolong clearance, but it is different for every person.
If psoriasis lesions return, an individual may return to three treatments per week. Sometimes a person is rotated to a different psoriasis treatment. This rotation gives the skin a break from UVB, minimizing long-term exposure and possible side effects.
The Goeckerman regimen
Some people with severe psoriasis are referred to a hospital or psoriasis day treatment center for three to four weeks of treatment with UVB and prescription coal tar. This is called the Goeckerman [GEK-er-man] regimen. Once or twice daily, crude coal tar is applied and then removed before the patient is exposed to total body UVB light. This is followed by a cleansing bath or shower to remove the residual tar and scales.
The regimen can be supplemented with steroid medications and keratolytics (scale removers), particularly in the early stages of treatment. In a modification of the Goeckerman regimen, anthralin is used instead of coal tar (this is called the Ingram regimen).
To be admitted to a psoriasis day treatment center for Goeckerman treatment, a person must:
- Be able to walk without help
- Be free of health problems that could complicate treatment
- Be able to commute to the center daily for three to five weeks
- Go home or to other lodgings for evenings and weekends
A limited number of day treatment centers for psoriasis exist in the United States.
Intensive inpatient Goeckerman treatment in the hospital may be necessary for certain people. Sometimes a person's emotional as well as physical condition requires medical supervision. Bed rest and removal from the stresses of daily life are important additional elements of hospital Goeckerman therapy.
Average remission times of six to 12 months have been reported by Goeckerman regimen patients. Less intensive coal tar and UVB treatments available in a doctor's office are often referred to as modified Goeckerman regimens.
What are the side effects of UVB treatment?
During treatment, psoriasis may worsen temporarily before improving. The skin may itch and become red because of exposure to the UVB light. The amount of UVB administered may need to be reduced to avoid further irritation. Occasionally, temporary flares occur even with non-burning doses of UVB. These reactions may resolve with continued UVB treatment.
Irritation
If coal tar is applied, skin pores can clog and cause small pimple-like eruptions (folliculitis). Eruptions are caused by applying the coal tar incorrectly. Coal tar should be stroked on the skin in the same direction the hair grows. Folliculitis is not permanent, but occasionally it requires some patients to stop using coal tar preparations.
Sunburn
Certain medications, herbal supplements and topical ingredients can cause sensitivity to light; it is important to tell your doctor about all medications, treatments and supplements you are taking. Patients should avoid exposure to natural sunlight on UVB treatment days. Overexposure to ultraviolet light can cause a serious burn.
Skin cancer
UVB is an established carcinogen (cancer-causing substance or agent) in humans. However, there is no direct evidence of increased risk of skin cancer from UVB treatment for psoriasis. It is important to have a doctor examine your skin periodically. Skin cancers generally can be removed easily if detected early.
Some doctors recommend the use of sunscreen on uninvolved skin as a means of minimizing exposure to UVB. The face, for example, is exposed to a great deal of natural sunlight. If there is no psoriasis on the face, a person should avoid UVB exposure there.
Updated December 2005
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