People’s Pharmacy: Cough medicine creates dangerous interaction

Q. I experienced serotonin syndrome once even though I used a drug interaction checker. Unfortunately, it was difficult to use. As a result, I had a scary experience.

Being a wary person, I went to an online interaction checker and typed in “Prozac.” When it told me that it found no drug interactions, I typed in “fluoxetine.” Again, nothing.

So, I, a Prozac patient, went ahead and took my cough medicine. Before long, I was frazzled, agitated, trembling and saying things that made no sense. Luckily, this subsided after a few hours.

Suspecting an interaction, I went back to that interaction checker and typed in “fluoxetine dextromethorphan.” Presto! I saw that this combination could have sent me to the hospital. Why isn’t this better known?

A. Many antidepressants, including fluoxetine (Prozac), paroxetine (Paxil) and sertraline (Zoloft), can interact with cold medicines containing the cough suppressant dextromethorphan (DM) or the antihistamine chlorpheniramine (British Journal of Clinical Pharmacology, December 2010). This potential interaction is not widely recognized.

The resultant serotonin syndrome can be life-threatening. Symptoms may include confusion, agitation, diarrhea, nausea or vomiting, rapid heart rate, muscle spasms, fever, overactive reflexes, hallucinations and rapid changes in blood pressure.

Investigators found that nearly 8% of the patients in an intensive care unit met criteria for serotonin syndrome, though none had been diagnosed (Journal of Critical Care, June). Most of these patients had taken at least two serotonergic drugs, including ondansetron (Zofran), tramadol (Ultram), dextromethorphan or chlorpheniramine.

Q. My Medicare Advantage Plan is always trying to get me to have my medicines mailed because it is cheaper. Instead, though, I get my prescriptions filled locally, where I know my pharmacist.

One time, a doctor prescribed me a new drug. Since I was in a hurry, I stopped at the nearest pharmacy. When they quoted the price, I said, “Oh no!”

I drove a few blocks farther and went to my usual pharmacist. When he looked at the prescription, he told me my insurance would not cover it. They would cover an alternative, however, and he named it. Then he advised me to call the doctor to see if that would work as a substitute.

I did, and she prescribed it. I am still using this medicine, which is working well. That’s the reason I refuse to buy my medicines through the mail. The slight extra cost is well worth it.

A. Having a vigilant pharmacist who is watching out for potential drug interactions as well as what your insurance will and won’t cover is invaluable. Finding an affordable alternate medication can sometimes be challenging.

If there is no substitute, there are a couple of options. Consumer Reports mentions that Costco has good prices at their pharmacies, which you can use without becoming a member.

They also suggest checking goodrx.com to learn the drug’s fair price. Coupons found there can sometimes save you quite a bit.

To learn more about these and other cost-saving strategies, you may be interested in our eGuide to Saving Money on Medicines. This online resource may be found under the Health eGuides tab at peoplespharmacy.com.

In their column, Joe and Teresa Graedon answer letters from readers. Write to them in care of King Features, 628 Virginia Drive, Orlando, FL 32803, or email them via their website peoplespharmacy.com.