Like UVB, ultraviolet light A (UVA) is present in sunlight. Unlike UVB, UVA is relatively ineffective unless used with a light-sensitizing medication psoralen, which is administered topically or orally. This process, called PUVA, slows down excessive skin cell growth and can clear psoriasis symptoms for varying periods of time.
The most common short-term side effects of PUVA are nausea, itching and redness of the skin. Drinking milk or ginger ale, taking ginger supplements or eating while taking oral psoralen may prevent nausea. Antihistamines, baths with colloidal oatmeal products or application of topical products with capsaicin may help relieve itching. Swelling of the legs from standing during PUVA treatment may be relieved by wearing support hose.