Serotonin is a type of hormone in your body. It helps send signals in your brain and nervous system. Medicines that treat depression and anxiety can raise the amount of serotonin in your body. Some supplements can increase your serotonin. And some illegal drugs can do this, too. If you have too much serotonin in your body, it can lead to dangerous side effects. This is known as serotonin syndrome. Tell your doctors about all medicines you take. This can help prevent serotonin syndrome.
How to say it
Seer-uh-TOH-nihn
SIHN-drohm
What causes serotonin syndrome?
Serotonin syndrome can happen:
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If you increase the dose of a medicine you are taking.
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When you start a new medicine.
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When certain medicines are combined.
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If you take supplements, medicines, or drugs that affect serotonin.
Symptoms of serotonin syndrome
Symptoms can range from mild to life-threatening and can include:
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Anxiety.
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Restlessness.
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Confusion.
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Large pupils.
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Headache.
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Nausea.
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Vomiting.
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Diarrhea.
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Fast heart rate.
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Fast breathing.
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Stiff or twitching muscles.
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Shivering or shaking.
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A lot of sweating.
Diagnosing serotonin syndrome
There is no test for serotonin syndrome. Your doctor will give you a physical exam. They will ask questions about the medicines you take. Tell them:
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All the prescription and over-the-counter medicines you take.
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Any vitamins, herbs, or other supplements you take.
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If you take illegal drugs and what drugs you have used.
Treatment for serotonin syndrome
Treatment will depend on how bad your symptoms are. For mild symptoms, you may just need to stop taking certain medicines. For more severe symptoms, you may need extra oxygen or I.V. (intravenous) fluids. You may need to stay 1 or more nights in the hospital. You may be given medicine to lower the amount of serotonin your body makes.
Possible complications of serotonin syndrome
If untreated, serotonin syndrome can lead to:
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Seizures.
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Kidney failure.
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Death.
Call 911
Someone should call
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You passed out (lost consciousness), fainted, or are unresponsive.
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You have seizures.
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You have confusion, extreme drowsiness, or trouble waking up.
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You have a rapid, irregular heartbeat or pulse.
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You have trouble breathing or shortness of breath.
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You have chest pain.
When to contact your doctor
Contact your doctor if:
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You have a fever of 100.4°F (38°C) or higher, or as directed by your doctor.
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You have symptoms that don’t get better, or get worse.
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You have new symptoms.
Date Last Reviewed: 05/01/2025
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