UVB Phototherapy is a treatment for skin eruptions using artificial ultraviolet light. The initials UVB stand for the type B ultraviolet, the middle energy between the tanning rays (UVA) and the intense germicidal UVC. UVB rays are the part of sunlight that gives one sunburn. Carefully controlled, it is an extremely effective tool for significant skin disease.
UVB has been a standard therapy in hospitals and clinics since its invention at the Mayo Clinic in the 1920s. UVB is the treatment of choice for people with moderately severe psoriasis (covering 20 percent or more of their body) who have not responded to topical ointments. UVB is also used for severe cases of eczema and itching from any cause.
UVB improves skin diseases because the immune cells of the skin, overactive in many skin diseases, are shut down by UVB. The effect of UVB is similar to sunlight. Excessive exposure causes premature aging of the skin and increases the risk of skin cancer. There are guidelines as to how many times UVB can be done safely.