Q. My daughter just told me a horror story about a close friend of hers. This young woman became depressed at college and was taking Zoloft. When she caught a bad cold and took over-the-counter cough syrup, she ended up with a severe panic attack and was so agitated she had to be hospitalized. What is there in cough syrup that would triggered such a reaction?
A. Most people do not realize that dextromethorphan (DM) in over-the-counter cough remedies may interact with some antidepressants. Medications such as paroxetine (Paxil), fluoxetine (Prozac), nefazodone (Serzone) and sertraline (Zoloft) might trigger serotonin syndrome in combination with dextromethorphan or other drugs.
Excessive serotonin activity can lead to symptoms such as agitation, anxiety, incoordination, confusion, sweating and muscle jerks. Such a reaction could easily be mistaken for a panic attack.
In some cases serotonin syndrome can be life threatening.
Two years ago we got a desperate phone call from a friend. He was afraid his wife had suffered a stroke. She was in a coma, unresponsive and he feared he would soon be forced to decide whether to discontinue life support.
A CT scan, however, revealed no signs of stroke. The neurologists were puzzled. They began to suspect an infection in the brain, but cultures came back negative.
After four days she began to return to consciousness and gradually recovered full brain function. The doctors were mystified.
Our friend began doing some research and asked us whether the Maxalt his wife took for a migraine headache might have interacted with the Zoloft she was taking to prevent migraines. Bingo! Both medications can raise serotonin levels and together they can cause serotonin syndrome.
This woman had experienced all the symptoms of this potentially deadly condition. Although her experience was reported to the FDA, the agency did not express much interest in it. For the most part, doctors do not recognize serotonin syndrome, and consequently it is infrequently diagnosed.
At last, though, the FDA has issued a Public Health Advisory to warn physicians of the hazards of mixing migraine medicines such as Amerge, Axert, Frova, Imitrex, Maxalt, Naramig, Relpax and Zomig with many popular antidepressants. Drugs like Celexa, Lexapro, Paxil, Prozac, Symbyax and Zoloft, or related medications such as Cymbalta and Effexor fight depression in part by changing levels of the brain chemical serotonin.
Combining them with other medicines that affect serotonin, including the migraine drugs above, could be dangerous. Other drugs that may interact badly with these antidepressants include the diet pill Meridia, prescription pain relievers such as Demerol or tramadol (Ultram), the nonprescription cough medicine dextromethorphan (Robitussin DM, among others) and some herbal products containing St. John’s wort.
Some people may experience serotonin syndrome as a result of interaction with an OTC drug. Several years ago, we heard from a teacher who was taking Paxil. When he caught the flu, he took a nighttime cold medicine so he could get some sleep. Instead, by the middle of the night he was extremely agitated, dizzy and shaking. When he began throwing up, his wife took him to the emergency room, where he was diagnosed with serotonin syndrome.
As the FDA cautions, people taking two prescribed medicines that may interact should talk with their doctors before discontinuing either drug. But it makes sense to be aware of the danger.
Symptoms of excess serotonin include anxiety, restlessness, rapid heart beat, sweating, nausea, vomiting, diarrhea, uncontrollable tremors or muscle contractions, lack of coordination, confusion, high blood pressure, hallucinations or coma. The syndrome may be mild, with dizziness, nausea and sweating, or it may be severe, landing someone in the hospital in a coma, or even killing him.
We are grateful that our friend’s wife survived her terrible experience with serotonin syndrome. We are glad the FDA is finally warning the American public and their doctors about this potentially deadly drug interaction.
People taking antidepressants should always check for interactions before taking any other medications, including over-the-counter remedies.
Read more about serotonin syndrome and other dangerous drug interactions in our book, Top Screwups Doctors Make and How to Avoid Them. It shocks us how many physicians are still unaware of serotonin syndrome and how dangerous it can be.
