What is serotonin syndrome?

Reviewed by Yoshinori Abe, MD

Internal Medicine

Serotonin syndrome is a potentially life-threatening condition caused by excessive serotonin activity in the brain, typically triggered by certain medications, drug interactions, or overdoses. Common symptoms include agitation, rapid heart rate, high blood pressure, dilated pupils, muscle rigidity, tremors, sweating, and confusion. In severe cases, it can lead to seizures, high fever, or unconsciousness, requiring immediate medical attention.

If you're experiencing any of these symptoms—or worried a medication may be affecting you—don't wait to find out what's happening. Taking a free, instant, online symptom check can help you quickly identify possible causes, understand the urgency of your symptoms, and guide your next steps. It's private, doctor-developed, and takes just a few minutes—an easy, informed first move toward getting the right care.

Reviewed for medical accuracy: 07/20/2026

Important Next Steps

Learn if serotonin syndrome matches your symptoms Discover if your symptoms need urgent care Find out what’s causing serotonin syndrome symptoms See OTC options for symptom relief Find a doctor for serotonin syndrome Understand medically proven serotonin syndrome home care Check if serotonin syndrome needs immediate treatment

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Explanation

Serotonin syndrome is a potentially life-threatening condition that can occur when there is an excess of serotonin, a chemical in the brain. This often happens when someone takes medications that increase serotonin levels, such as certain antidepressants or other drugs.

Causes:

Taking multiple medications that increase serotonin
Increasing the dose of a serotonin-related medication
Using illegal drugs like ecstasy

Symptoms:

Agitation or restlessness
Confusion
Rapid heart rate
High blood pressure
Dilated pupils
Muscle twitching

What to Do: If you suspect serotonin syndrome, it is important to seek medical attention immediately. Stopping the medication that caused it and getting supportive care can help manage the symptoms.

If you're experiencing any concerning symptoms, take a free AI symptom checker test to help understand what might be happening and determine if you need immediate care.

(References)

Sporer KA. (1995). The serotonin syndrome. Implicated drugs .... Drug safety, 7576268.
Mason PJ, Morris VA, & Balcezak TJ. (2000). Serotonin syndrome. Presentation of 2 cases and review .... Medicine, 10941349.
Sun-Edelstein C, Tepper SJ, & Shapiro RE. (2008). Drug-induced serotonin syndrome: a review. Expert opinion on drug safety, 18759711.

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