DEAR DR. DONOHUE: Can you please help me get some relief from psoriasis? I have used creams and ointments, but nothing has helped me. It is so uncomfortable and itchy all the time. Can sunlight treat it? – S.D.

ANSWER: Seven million of your fellow citizens battle psoriasis along with you. It’s one more example of an illness in which the immune system plays a pivotal role. Ordinarily, it takes immature skin cells – located in the deepest part of the skin – one month to reach the skin’s surface. In psoriasis, due to the influence of a misbehaving immune system, immature cells arrive at the skin’s surface in three or four days. Such cells don’t function like fully developed skin cells.

The infant skin cells pile up in red patches with silvery scales. The patches can be found anywhere, but they are most common on the elbows, the knees, the scalp and the lower back. They can itch, burn or do neither.

Mild psoriasis is defined as affecting less than 2 percent of the skin. Creams, lotions, ointments and sprays applied to the skin – so-called topicals – can often control it. Many of these products contain a cortisone drug. Names of some are Diprolene, Temovate and Aristocort. Dovonex and Tazorac are two other topicals often prescribed. They are not cortisone drugs.

For more extensive skin involvement, oral medicines such as methotrexate and Acitretin can often control outbreaks.

The latest treatments are medicines called biologicals. Three such drugs are Raptiva, Humira and Enbrel. They are self-administered injections used in the manner diabetics use insulin, but they are not lifelong treatments. Two other injected biologicals are Amevive and Remicade, administered by a doctor or nurse.

Sunlight can help some psoriasis patients, as can artificial ultraviolet light.

DEAR DR. DONOHUE: Where does the fat go and in what form does it go when a person loses weight by dieting? – B.S.

ANSWER: Fat is burned as a fuel for energy, like gasoline is in a car. Fat is, in a sense, stored fuel. When there’s a deficit between calories brought into the body and calories used up by the body for energy, fat makes up for the deficiency. Waste products of fat burning include things like carbon dioxide, which is breathed out of the body.

Dr. Donohue regrets that he is unable to answer individual letters, but he will incorporate them in his column whenever possible. Readers may write him or request an order form of available health newsletters at P.O. Box 536475, Orlando, FL 32853-6475. Readers may also order health newsletters from www.rbmamall.com