DEAR DR. ROACH: I would appreciate any advice on dealing with seborrheic dermatitis. I have scratched areas until I bleed. I was told to use Selsun Blue shampoo and hydrocortisone cream, which help. It affects my back, face and scalp. Is this caused by sebaceous glands in skin? — S.L.

ANSWER: Seborrheic dermatitis is a very common problem, but what causes it is incompletely understood. The most current theory is that it is due to a reaction to a fungus on the skin, Malassezia, which colonizes the skin in people with seborrheic dermatitis. The fungi grow in areas with lots of sebaceous glands, which secrete oils to moisturize the skin. The most common locations are on the face, especially the sides of the nose, the eyebrows and the scalp. It can appear on the trunk, where it can be confused with other skin conditions. Most people come to the doctor because of the appearance; itching is fairly common, but you describe worse itching than I usually see. A skilled clinician, such as a dermatologist, usually can make the diagnosis just by looking at it, but a skin biopsy is occasionally necessary.

Because your body seems to be reacting to the yeast, you were prescribed Selsun Blue, which contains selenium. It reduces the body’s inflammatory response. Steroids, the most gentle of which is hydrocortisone, also reduce inflammation on the skin. Tar shampoos (such as T-gel) also have anti-inflammatory properties and are more effective in some people. Sometimes, physicians recommend treatment with an antifungal shampoo to reduce the amount of yeast.

Since it seems you have had only partial response to the steroid and selenium, it might be worth a trial of tar shampoo or antifungal shampoo. These are sold over the counter, but prescription strengths are available. Ketoconazole gel or cream may be prescribed for use on your face.

DEAR DR. ROACH: I am a 78-year-old retired airline pilot recently diagnosed with mid-stage ALS. I’m exhibiting all the classic symptoms. There are no treatment options other than Rilutek, which gives only an additional six months at most, with some serious side effects. I have been reading about a very promising drug called GM 604. Can you possibly expand on this drug? They claim it has arrested progression in 7 out of 8 trial subjects. I know it’s a rare disease, but the outcome is fatal except in a few isolated cases — Stephen Hawking, for one. The company claims ”compassionate dispersal,” I would imagine to get around the Food and Drug Administration. — J.P.

ANSWER: I did read through the results of the GM 604 trials, and although the evidence is preliminary, the drug appears to be safe. The study results and case reports show significant improvement. The results are far from definitive, however.

Given that there are no other good options (Rilutek is quite limited, as you say), I certainly would recommend you try the drug, either as part of a study or through the drug company if it becomes available for compassionate use. Unfortunately, I can’t find a way at the current time for people with ALS in the U.S. to get the medication.

The FDA needs to balance risks and benefits of every potential new medication, but since ALS is uniformly fatal, usually quickly (Dr. Hawking has a rare, slowly progressing form), I urge evaluation as rapidly as possible to hopefully get this drug available.

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Dr. Roach regrets that he is unable to answer individual letters, but will incorporate them in the column whenever possible. Readers may email questions to ToYourGoodHealth@med.cornell.edu or request an order form of available health newsletters at 628 Virginia Dr., Orlando, FL 32803. Health newsletters may be ordered from www.rbmamall.com.