A number of tablet treatments are available, and these have proven very effective in most people living with psoriasis but, like all medications and therapies, can cause potentially serious side effects. These treatments include methotrexate, acitretin and cyclosporin. Careful choice of therapy and skilled monitoring reduce the potential risks of these therapies, which are generally very effective in controlling even severe cases of psoriasis. Methotrexate and cyclosporine work by largely modulating the immune system. Acitretin is a derivative of vitamin A. Acitretin helps program the skin cells back to normal and also has effects on the immune system.
Corticosteroids are generally teratogenic in laboratory animals when administered systemical-ly at relatively low dosage levels. The more potent corticosteroids have been shown to be ter-atogenic after dermal application in laboratory animals. There are no adequate and well-controlled studies in pregnant women on teratogenic effects from topically applied corticosteroids. Therefore, topical corticosteroids should be used during pregnancy only if the potential benefit justifies the potential risk to the fetus. Drugs of this class should not be used extensively on pregnant patients, in large amounts, or for prolonged periods of time.
PUVA is a special treatment using a photosensitizing drug and timed artificial-light exposure composed of wavelengths of ultraviolet light in the UVA spectrum. The photosensitizing drug in PUVA is called psoralen. Both the psoralen and the UVA light must be administered within one hour of each other for a response to occur. These treatments are usually given in a physician's office two to three times per week. Several weeks of PUVA is usually required before seeing significant results. The light exposure time is gradually increased during each subsequent treatment. Psoralens may be given orally as a pill or topically as a bath or lotion. After a short incubation period, the skin is exposed to a special wavelength of ultraviolet light called UVA. Patients using PUVA are generally sun sensitive and must avoid sun exposure for a period of time after PUVA. Common side effects with PUVA include burning, aging of the skin, increased brown spots called lentigines , and an increased risk of skin cancer , including melanoma . The relative increase in skin cancer risk with PUVA treatment is controversial. PUVA treatments need to be closely monitored by a physician and discontinued when a maximum number of treatments have been reached.