A Guide to Using Light Therapy for Psoriasis

Phototherapy is the original psoriasis treatment. For as long as people have had the disease, they’ve treated it with sunlight. Even today, with all the high-tech remedies available, light therapy continues to be one of the most effective treatments for psoriasis, an autoimmune disorder that causes skin cells to grow too rapidly, resulting in red, itchy lesions on the surface of the skin.

“When ultraviolet light hits skin, it does all kinds of things,” says Steven Feldman, MD, PhD, a professor of dermatology at the Wake Forest University School of Medicine in Winston-Salem, N.C. Ultraviolet light kills the immune cells in the skin that contribute to psoriasis, and research suggests that UV light may also disrupt the faulty signals between immune cells and skin cells that lead to psoriasis lesions.

With relatively few side effects, phototherapy is an effective—yet underused—treatment, experts say. “Phototherapy is a great treatment to start with,” recommends Kathy Kavlick, RN, community outreach nurse for the Murdough Family Center for Psoriasis in Cleveland. “Some people get really good results from it.”

Types of phototherapy
Phototherapy is usually administered on an outpatient basis in a dermatologist’s office two to three times a week, using a walk-in light booth that looks like a tanning bed stood on end. Light boxes for home use are also available.

There are two main types of phototherapy:

• Ultraviolet B light (UVB), one of the components of sunlight, is especially effective for treating psoriasis. During the treatment patients are exposed to the light for just a few seconds at first, and the exposure time is gradually increased to several minutes per treatment. UVB treatment is sometimes administered with topical treatments such as coal tar, anthralin, or just mineral oil. A form of UVB light known as narrow-band (NB-UVB) has been shown to be even more effective than UVB, and is increasingly being used by dermatologists.
  
  
• Although not as potent as UVB, ultraviolet A light (UVA) is also used to treat psoriasis. UVA treatment generally takes longer than UVB—exposure times can reach 15 to 20 minutes—but at these higher doses it is also effective in clearing lesions. UVA light is often combined with an oral medication known as psoralen (a treatment known as PUVA).

A newer variation of phototherapy uses excimer or pulsed-dye lasers to target individual plaques. Research suggests that laser therapy may require fewer treatments and produce longer remissions, but since this technique is so focused it is not very practical for people with widespread lesions. As Dr. Feldman notes, however, roughly eight out of 10 people with psoriasis have lesions only in small, isolated spots, and laser therapy may grow more popular as the technology becomes faster and more effective.