Your doctor may suggest this psoriasis treatment if the medicine you put on your skin isn’t helping. It uses ultraviolet rays -- from sunshine, artificial lamps, or lasers -- to slow skin-cell growth and ease your symptoms.
Types of Phototherapy
Sunlight. Getting sun is a simple way to help your skin condition. But that doesn’t mean you should go bake at the beach. Too many rays can make your symptoms worse and raise your chances of getting skin cancer.
If your doctor tells you to get some sun each day, make sure you don’t stay out too long. About 20 minutes a day should be enough. Use a sunscreen with an SPF of 30 or higher with zinc oxide on areas of your skin that don't have psoriasis.
UVB (Ultraviolet B). You can get UVB rays from sunlight, especially summer noontime sun. But no matter what the time of day, sunlight also carries UVA rays, which are linked to cancer and rapid aging.
The doctor can treat you with UVB rays from a phototherapy unit in his office. You can get one to use at home, but these lamps can also give off UVA rays.
You’ll probably need phototherapy treatments 3 days a week for 2 to 3 months.
Your doctor might suggest you combine UVB treatment with another therapy. A common method is to apply a cream made from coal tar to your skin. He may call this the "Goeckerman regimen."
PUVA (Psoralen plus Ultraviolet A). This combines ultraviolet A lamp sessions with a drug called psoralen, which you take as a pill or put on your skin as a cream. It makes your skin more sensitive to light. Your doctor might call this “photochemotherapy.”
PUVA clears up severe psoriasis quickly, with long-lasting results. There are some side effects, though, including:
Using PUVA over a long time can also raise your risk of skin cancer. It's mostly reserved for extreme cases or when other treatments haven't worked. You’ll probably go to your doctor’s office two or three times a week for a total of 25 sessions.
Psoralen makes your body extra sensitive to light. You need to protect your skin and eyes after taking it. Wear glasses that block ultraviolet light, and apply sunscreen for at least 24 hours after treatment.
Lasers. These highly focused beams of light target your psoriasis patches, not your healthy skin. This cuts down on side effects and may lower your chances of skin cancer. You’ll also need fewer treatments compared to other types of light treatment.
The excimer laser uses focused, high-energy ultraviolet B light. It can help patches get better faster than other methods. You usually get this treatment in your doctor's office twice a week for 4 or 5 weeks.
Side effects from laser therapy are generally mild, although some people feel pain. You may also have bruising, sunburns, and maybe scarring at the spots where you've been treated.
After laser treatment, you should avoid sunlight and be careful not to injure the area. Call your doctor if you see blisters.
If you're using any kind of phototherapy, including natural sunlight, make sure you aren’t being exposed to risky levels of ultraviolet rays. It’s easier than you might think. If you're using UVB or PUVA, don’t sun yourself in the yard or go out for a walk without sunscreen.
During an artificial light session, use sunscreen or wear clothing that covers up areas that don't need treatment.
Many things can make you more sensitive to light, like some blood pressure drugs, antibiotics, St. John's wort, and even celery. Avoid them when you're getting phototherapy. Have regular skin exams to check for signs of skin cancer.