Cough medicine plus antidepressant caused serotonin syndrome

Q: Several years ago, my daughter was on a low dose of escitalopram (Lexapro). Once, when she had a cough, I gave her a generic version of Robitussin DM just before she left for school. Within minutes, she began acting confused and had difficulty walking.

I remembered reading about serotonin syndrome, so my husband and I took her to an urgent care center. At first the doctor there told us our daughter was fine. Before we left, however, she came back and told us that our daughter had symptoms of serotonin syndrome and that we should get to the hospital ASAP. The doctor in the emergency room said she would watch our daughter for several hours to see what would develop. Luckily, she recovered without incident.

All in all, it was a lesson learned that I’ll never forget: ALWAYS inquire about possible drug interactions from now on.

A: Serotonin syndrome occurs when levels of the neurotransmitter serotonin rise dangerously. Symptoms may include the confusion and gait disturbance you noted in your daughter. Shivering, restlessness, sweating, tremors, muscle twitches, elevated temperature, diarrhea and vomiting are other signs. Blood pressure and heart rate also may rise. This can become a life-threatening situation.

Many people don’t realize that something as simple as an over-thecounter cough medicine containing dextromethorphan could cause a problem as serious as serotonin syndrome. The DM in the cough medicine apparently interacted with your daughter’s antidepressant, escitalopram.

Other antidepressants that act on serotonin, such as fluoxetine (Prozac) or sertraline (Zoloft), also may trigger serotonin syndrome, particularly when combined with another medication such as a triptan for migraine treatment, tramadol for pain or the antibiotic linezolid. The interaction of escitalopram and dextromethorphan has caused serotonin syndrome leading to hospitalization (BMJ Case Reports, Aug. 7, 2017).

You can learn more about preventing dangerous drug interactions from our book “Top Screwups.” It is available in libraries or online at www.PeoplesPharmacy.com.