Psoralen and Ultraviolet Light A therapy, or PUVA therapy, is prescribed by a dermatologist for the treatment of chronic skin conditions. This therapy uses a combination of plant-derived chemicals and UVA light to treat disorders such as psoriasis, vitiligo and eczema. PUVA therapy is also called photochemotherapy or phototherapy.
Several plants, including cloves, figs, parsley, celery, lemon and lime, contain chemicals called psoralens. These chemicals, when ingested orally or applied to the skin, have the effect of increasing the sensitivity of skin to ultraviolet light. Psoralen tablets are ingested several hours before UVA light treatment. Psoralen topical preparations are applied shortly before the treatment. UVA light treatment begins once enough time has passed to ensure that skin cells have been exposed to and have ingested the psoralen.
The combination of psoralen and UVA light that is utilized in PUVA therapy causes skin cells to divide less rapidly. This is an effective treatment for skin disorders such as psoriasis, vitiligo and eczema because part of the pathogenic process of these disorders is an increase in the rate of cell division. By reducing the rate of cell division, symptoms of skin disorders are eased, and progression can be slowed down.
During PUVA therapy a patient can be exposed to ultraviolet light in one of two ways, depending on the type of skin condition he or she has. If the skin condition affects the hands and feet only, the patient is treated with a topical psoralen cream that is applied to those specific areas. The patient then sits in a chair and places his or her hands and feet in small UVA light boxes. If the skin condition affects other parts of the body, the patient is given oral psoralens and is treated with UVA light by sitting inside a large light box that allows full-body exposure.
PUVA therapy can cause side effects, most of which affect the skin. Within one to two days following a treatment, the skin will take on a slightly pink or reddish tone. After several treatments, the skin might tan or darken. Sometimes the skin can become burned; this generally occurs if the skin has received too high of a dose of UVA light. Burned skin is deeply pink or red, painful and can blister. The eyes and other sensitive parts of the body, including the groin and armpits, must be shielded from the UVA light to prevent serious burns.
The use of psoralens also can cause side effects that might include dry skin, itchy skin, dizziness, headaches and nausea. People who undergo this type of therapy should avoid additional sun exposure, particularly on days when they have treatment scheduled. Long-term use of this therapy can cause premature skin aging, including wrinkling and pigmentation spots. In addition, the risk of skin cancers and benign skin growths is increased. Awareness of this risk considerably reduces the possibility of life-threatening disease, because skin cancers can be treated effectively when diagnosed early.
