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.