DEAR DR. DONOHUE: My scalp has been very itchy. I used many shampoos without any relief. I finally saw a dermatologist, who diagnosed me as having seborrheic dermatitis. My girlfriend says that it’s dandruff. Did I see a specialist only for dandruff? I want my money back. – D.J.

ANSWER: Seborrheic dermatitis is a chronic and often relapsing skin condition in areas of the skin with a large supply of oil glands. Seborrhea means “running with oil.” The scalp is only one place where it occurs. It can affect the face, the lines running from the sides of the nose toward the chin, the chest, the eyelids and the ears – both behind them and within the ear canal. Involved skin is red with scales. Dandruff is one manifestation, but not the only one. Dandruff can be something most difficult to treat.

Oil glands give the condition its name, but they aren’t the source of trouble. A fungus whose name is Malassezia is. It produces byproducts that irritate and inflame the skin.

Many over-the-counter shampoos and lotions can be quite effective against this fungus, but sometimes, as in your case, prescription shampoos, lotions, creams or gels are needed to eradicate Malassezia. Ketonconazole and ciclopirox are two examples.

Selenium sulfide shampoo also works. The nonprescription brands of this material have a lower concentration of it than do the prescription preparations, which contain 2.5 percent selenium sulfide. It often takes the stronger items to do in the fungus.

You didn’t waste your money. Lots of people have to consult a dermatologist for control of seborrheic dermatitis. You weren’t getting anywhere with self-treatment. You’ll be glad you spent your money for a plan that brings success.

DEAR DR. DONOHUE: My father was 67 when he passed away in 1989 from ALS, Lou Gehrig’s disease. He had it for only two years. I am 60 years old and a Vietnam veteran from 1968. I had extensive nerve and muscle wounds in both legs and my left arm from the war. I get muscle spasms in my legs and am concerned that it might be ALS. Is ALS hereditary? – B.W.

ANSWER: Only in a few cases, 5 percent to 10 percent, does heredity play a major part in ALS. ALS is amyotrophic lateral sclerosis. It’s a dying off of nerve cells in the brain and spinal cord that control muscle movement. In its final stages, it leaves a person a prisoner of his own body, unable to move and often unable to swallow or talk.

The initial symptom of ALS is muscle weakness, not muscle spasms. You’re not likely to have this illness.

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.