I liked your article on relieving jock itch by using Cetaphil skin cleanser. I tried it, and it works great.

My family doctor recommended an alternative to Cetaphil: Selsun Blue dandruff shampoo. Apply it to the affected region and work up a lather. I leave the lather in place for five minutes and then rinse it off. This also works very well.

Jock itch is caused by a fungal infection and can trigger pain and itching. There are a variety of over-the-counter antifungal creams that are quite effective. They contain the same ingredients as athlete’s foot treatments.

Cetaphil contains propylene glycol, which has antifungal activity. The selenium sulfide in Selsun Blue fights the yeast that causes dandruff. Because yeast is a type of fungus, we’re not surprised that dandruff shampoo also works for jock itch.

I’m becoming a social recluse because of embarrassing digestive problems. Over the past six months I have become constipated and produce a great deal of gas.

These problems first cropped up after I started some new prescriptions Actonel for osteoporosis and Paxil for anxiety. Could they be responsible? My doctor says the medicines wouldn’t cause gas and told me to keep track of foods that cause trouble. Controlling the gas has become so difficult that I don’t want to go out with friends, attend church or even visit relatives.

It’s always a good idea to keep a record of foods and of “flatus events” so you can figure out which foods to avoid. But medications can be an overlooked source of both flatulence and constipation. Both Actonel and Paxil have been linked to these side effects. Perhaps your doctor could consider alternate drugs.

Is prescription Motrin better than over-the-counter ibuprofen? A friend of mine is taking prescription Motrin, which is rather expensive. I told him he could substitute nonprescription Motrin or Advil and save money, as long as he takes the same number of milligrams. Is this advice OK, or is there something special in the prescription product?

You are correct. At the same dose, and with the exception of inactive ingredients, nonprescription ibuprofen is identical to prescription Motrin.

Joe Graedon is a pharmacologist. Teresa Graedon holds a doctorate in medical anthropology and is a nutrition expert. Write to them in care of King Features Syndicate, 235 E. 45th St., New York, N.Y. 10017, or e-mail them via their Web site, www.peoplespharmacy.com.