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 it's invention at the Mayo Clinic in the 1920s. UVB is the treatment of choice for people with moderately bad 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.

Initially most patients have their treatment three times a week for a total of 20 to 30 treatments. The first few exposures will be couple of minutes or so. The length of exposure is gradually increased aiming to turn the skin slightly pink. After a few months, a weekly maintenance treatment is often advised. This is especially important when conditions other than psoriasis are being treated. Psoriasis may remain clear for some months before flaring up again.

Significant side effects are uncommon, but a mild sunburn is not. It is at it's worst about 8 hours after the treatment and fades over the next few days. A severe blistering burn is rare when UVB is properly administered but can happen. Everyone will develop some degree of tan. Sometimes, after several rounds of UVB white and brown spots will appear on the skin. An occasional person will get worse or itch more from UVB.

The dermatologist must be told if any new medications are started, as some will make the skin abnormally sensitive to UVB. Apply mineral oil, baby oil or Vaseline to all scaly areas and SPF 15 or greater sunscreen to the face and hands before each treatment. Do not apply any prescription ointments or cosmetics to the affected areas until after the UVB treatment. Protective goggles and groin protection (underwear or towel) must be worn while getting the treatment. To protect the face from skin aging, a makeshift hood can be made from a brown paper shopping bag.

If improvement is not seen with UVB, medicated creams containing tar or anthralin may be added. A more potent form of light treatment called PUVA can also be helpful.

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