Serotonin syndrome: warning signs and triggers
Serotonin syndrome is an uncommon but serious reaction that can happen when medicines that raise serotonin are combined. Knowing the signs — and the combinations that can trigger it — helps you stay safe.
What can trigger it
It usually involves two or more serotonin-raising medicines, such as:
- Antidepressants (SSRIs, SNRIs, MAOIs, some others).
- Certain migraine medicines (triptans).
- Some pain medicines (tramadol, meperidine) and cough medicine (dextromethorphan).
- Certain supplements (St. John's Wort) and the antibiotic linezolid.
The risk is highest when starting or increasing one of these, or combining an MAOI with another serotonin medicine.
Warning signs
- Agitation, restlessness, or confusion.
- Fast heartbeat, high blood pressure, sweating.
- Shivering, muscle twitching or stiffness.
- Diarrhea, high fever (in severe cases).
When it's an emergency: High fever with muscle stiffness, severe agitation, or confusion after a medication change needs urgent care — call your local emergency number. Milder new symptoms after combining serotonin medicines are worth a prompt call to your prescriber.
Lowering your risk
Tell every prescriber and pharmacist about all your medicines, including OTC cough medicine and supplements. RxSafeCheck flags serotonin-raising combinations and the specific MAOI pairings clinicians avoid.
Check your own medicines free
See how your prescriptions, supplements, and food may interact — organized by the part of the body they affect.
Open the medication tool →Important: This article is educational and not medical advice. It does not replace your pharmacist or prescriber. Always confirm decisions about your medicines with a qualified professional, and call your local emergency number for emergencies. In the U.S., Poison Control is 1-800-222-1222.