Q. I take Zoloft (sertraline) for depression, but I had a frightening experience recently. I am in excellent physical health. To relieve a cold, I took one dose of a cold formula that contains dextromethorphan. The box warned about MAOI class antidepressants. It said nothing about Zoloft.

About an hour later, I began to experience chest pain, shortness of breath, shaking and tingling. Paramedics were called and found my EKG and blood pressure were fine, but my heart was racing. I had a textbook panic attack. I've never had one before.

When I refilled the Zoloft, I read the fine print the pharmacist supplied. I noticed, buried in a long list of drug names, that dextromethorphan was listed as harmful in combination with Zoloft. With so many Americans taking SSRI antidepressants, shouldn't there be a warning about this interaction?

A. You may have suffered serotonin syndrome. When too much of this brain chemical accumulates, symptoms may include agitation, rapid heartbeat, muscle twitching, sweating, shivering, nausea, diarrhea, elevated body temperature, changes in blood pressure and mental confusion.

Dextromethorphan (DM) is found in many cough and cold medicines, including Robitussin DM and NyQuil. Although there is a warning about interactions with monoamine oxidase inhibitors (MAOIs), there is no mention of SSRI antidepressants such as Prozac (fluoxetine) or Zoloft. Nevertheless, serotonin syndrome has been reported when DM is taken with this type of antidepressant (Clinical Toxicology, September 2008).

Q. I suffered flatulence and abdominal pain for more than three years to a degree of misery I'd like to forget. I had lots of tests for digestive problems, but they showed no problem, and my doctors could offer no help.

Eventually I figured out that my prescription medicine was causing the problem and stopped taking it, with my doctor's permission. I am now pain-free and no longer suffer from excessive gas.

A. Congratulations on superb problem solving. Many medications can cause stomach upset and flatulence. Some include osteoporosis drugs like Fosamax, cholesterol-lowering drugs like Tricor and even pain relievers like naproxen (Aleve, Naprosyn). We have a more complete list, along with a discussion of treatments for flatulence, constipation and heartburn, in our Guide to Digestive Disorders. Anyone who would like a copy, please send $3 in check or money order with a long (No. 10), stamped (61 cents), self-addressed envelope to:

Graedons' People's Pharmacy

No. G-3, P.O. Box 52027

Durham, N.C. 27717-2027

It also can be downloaded for $2 at peoplespharmacy.com.

peoplespharmacy.com