What is phototherapy?
Phototherapy, also called light therapy, means treatment with a special kind of light. It is prescribed to treat atopic dermatitis, contact dermatitis, dyshidrotic eczema, nummular eczema and seborrheic dermatitis.
The most common type of phototherapy used to treat eczema is narrowband ultraviolet B (UVB) light. This uses a special machine to emit UVB light, which is the best part of natural sunlight for treating eczema.
Broadband UVB phototherapy, PUVA (Psoralen and UVA), and UVA1 are other forms of phototherapy that may be used in special circumstances to treat eczema.
Phototherapy helps to:
- Reduce itch
- Calm inflammation
- Increase vitamin D production
- Ramp up bacteria-fighting systems in the skin
Phototherapy is used for eczema that is all over the body (widespread) or for localized eczema (such as hands and feet) that has not gotten better with topical treatments.
About 70% of people with eczema get better with phototherapy. Some people find that phototherapy puts their eczema in a “remittive” or “quiet” state long past the end of the treatment.
What should I expect with phototherapy?
- During your visit you will apply a moisturizing oil to the skin and stand in the cabinet undressed except for underwear and goggles to protect the eyes.
- The machine will be activated for a short time, usually just seconds to minutes, and will treat the entire body, or just certain exposed areas.
- Careful records are kept of your response and the light is slowly increased with each treatment.
- After several months of treatment, the frequency of the visits can sometimes be reduced to once or twice weekly.
- If things continue to improve, phototherapy can be stopped for a period to see if the eczema is in remission.
- If successful, some patients may restart the cycle or simply come once or twice weekly to maintain their improvement.
- When it does work, it is not a rapid improvement like some treatments. Generally it takes 1-2 months of steady treatment with phototherapy to start to see improvement in eczema symptoms.
What are the risks of phototherapy treatment?
Overall, phototherapy is considered safe. Known risks of phototherapy include:
- Skin aging
- Headaches and nausea (with PUVA treatment)
- Cataracts from insufficient eye wear during treatment
Light Therapy for Psoriasis
Types of phototherapy
Phototherapy is usually administered on an outpatient basis in a dermatologists 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 UVBexposure times can reach 15 to 20 minutesbut 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.
What works best
Patients generally require about 20 phototherapy sessions before they see an improvement in their skin. Although response rates vary, studies suggest that 65% of the patients who receive UVB treatment and 75% of the patients who receive NB-UVB will experience significant skin clearance. Although UVB treatments are more widely used, PUVA may actually be more effective.