Article: Ultraviolet B (UVB) therapy slows skin cell production, and may reduce the scale and dead skin buildup that is often associated with psoriasis. This therapy involves exposing affected skin to ultraviolet light for a brief period of time. The frequency of these treatments may depend on the condition of your skin or the type of UVB treatment. UVB therapy can be used to treat psoriasis that resists other forms of treatment.  Types of UVB therapy include broadband UVB therapy, narrow band UVB therapy, or limited daily exposure to natural sunlight (following your doctor's recommendations). Any type of UVB therapy may result in skin irritation or burns. Your doctor may recommend moisturizer or other topical treatments to reduce the severity of these side effects. For severe or hard-to-treat psoriasis, your doctor may recommend PUVA treatment, which combines a medication (psoralen) with exposure to UVA light. Psoralen helps UVA light penetrate deep into your skin in order to slow down the growth of new skin cells.  Psoralen may be administered as an oral medication (in pill or tablet form) or as a topical treatment. PUVA treatment may result in more severe side effects than UVB therapy, including nausea, headaches, and skin irritation. PUVA therapy may also increase your risk of developing skin cancer and cataracts. Sometimes phototherapy is combined with other forms of treatment. For example, your doctor may recommend combining UVB therapy with topical coal tar. The coal tar not only helps ease symptoms of psoriasis, but it can make your skin more receptive to UVB radiation.

What is a summary?
Treat psoriasis with UVB therapy. Use psoralen plus ultraviolet A (PUVA) for severe psoriasis. Get combination light therapy.