Serotonin syndrome happens when you have too much serotonin (a normal chemical) in your body. It’s usually caused by taking drugs or medications that affect serotonin levels. Stopping the drug(s) or medication(s) causing serotonin syndrome is the main treatment.
Serotonin syndrome is a potentially life-threatening drug reaction that results from having too much serotonin in your body. Serotonin is a neurotransmitter, a chemical produced by nerve cells in your brain and other areas of your body.
Most people can safely take serotonin-affecting (serotonergic) medication when it’s prescribed at the appropriate dosage and under the guidance of their healthcare provider. Serotonin syndrome happens most often when you either take a new drug or take an increased dose of a drug that increases the level of serotonin in your body. If your body processes serotonin differently or it can’t process an increased amount of serotonin, serotonin syndrome symptoms can happen.
Serotonin syndrome can cause mild symptoms (like diarrhea or nausea) to severe symptoms (like high fever or seizures). In some cases, severe serotonin syndrome can be fatal if not recognized and treated quickly.
Healthcare providers first recognized serotonin syndrome in the 1960s, after the approval of the first antidepressant medications. Today, more serotonin-affecting medications are available. This has led to a growing number of cases of serotonin syndrome.
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Anyone who takes certain prescription medications, over-the-counter drugs, herbal or dietary supplements and illegal drugs that affect their body’s serotonin levels could be at risk for serotonin syndrome. It happens to people of any age.
Symptoms of serotonin syndrome and their severity vary from person to person. They can be mild to severe to even fatal.
If you’re taking a medication that affects serotonin and experience any of the following symptoms, call your healthcare provider or visit an urgent or emergency care facility right away.
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Symptoms usually begin within a few hours of taking a new medication that affects serotonin levels or increasing the dose of a drug you’re already taking. Nearly all people will experience symptoms within 24 hours of starting, adding or increasing the dosage of a serotonergic medication or product.
A rise in serotonin levels in your body causes serotonin syndrome. This increase in serotonin can happen if you:
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Antidepressants are the most commonly used medications that affect serotonin levels. When involved in serotonin syndrome, they’re often used with other serotonergic drugs that treat other conditions; for example, triptan migraine drugs or opioid pain medications.
Antidepressant drug classes and medication examples that can increase serotonin levels include:
Other medications can also affect your body’s serotonin level, especially when combined with other drugs that affect serotonin. These medications treat:
Other herbal and dietary supplements and illegal substances that affect serotonin levels and could cause serotonin syndrome include:
Medical experts still have much to learn about serotonin syndrome. If you have concerns about the possible serotonin-affecting medications you take, talk to your healthcare provider or local pharmacist.
There aren’t any tests to diagnose serotonin symptoms. Your healthcare provider usually makes the diagnosis based on the results of your physical exam, review of your symptoms and history of medications you take that affect serotonin levels.
You can assist your healthcare provider by telling them all the products you take, including prescription medicines, over-the-counter medicines, supplements, herbal products and illegal drugs. (Be honest. Don’t worry. Your healthcare provider is here to help you, not judge you.)
Your healthcare provider may order:
Your treatment depends on the severity of your symptoms.
Treatments, depending on your symptoms, may include:
If your case of serotonin syndrome was caused by an antidepressant, it may take several weeks for the medication to clear your body and for your symptoms to completely go away.
Don’t stop your medication or change your dose without talking to your healthcare provider first. However, if you have severe symptoms or your symptoms have worsened, seek emergency care. Serotonin syndrome can be life-threatening.
Without treatment, serotonin symptoms can cause:
It’s important to keep close tabs on all medications you take. Read all warnings on your drug’s packaging or informational sheets. They’ll tell you if there’s a risk of serotonin syndrome. Don’t stop taking any medication before talking with your healthcare provider first. Keep all of your healthcare providers updated about all the prescription medications, over-the-counter drugs, herbs and supplements and illegal drugs you take.
If you take an antidepressant (especially SSRIs or SNRIs) along with a triptan medication for headaches, your doctor should closely monitor you. The risk is thought to be rare or perhaps non-existent, as different subtypes of the receptor are targeted. The American Migraine Foundation generally considers the combination safe, and it’s felt that the benefits outweigh the risks. But just remember, you have a role, too: Call your healthcare provider if you experience any of the symptoms listed in this article.
Taking these precautions can help you and your healthcare team spot signs of serotonin syndrome early. Early identification may help you avoid more severe symptoms.
If you’re quickly diagnosed and treated, most people who have serotonin syndrome will see their symptoms go away completely within 24 to 72 hours.
After recovery, your healthcare provider can:
If you have symptoms (or worsening symptoms) of serotonin syndrome, call your healthcare provider right away or go to an emergency room. Be especially watchful if you’ve started a new drug or increased the dose of a drug you’re currently taking and these drugs are known to affect serotonin levels.
Don’t stop taking medications or change the dose of a medication without talking to your healthcare provider first.
A note from Cleveland Clinic
Be sure your healthcare provider — all of your healthcare providers — know all the medications and products you take. This includes prescription and over-the-counter medications, herbal and dietary supplements, and illegal drugs. Read the warning information and informational sheets that come with all of your medications. Learn the symptoms of serotonin syndrome. If you take antidepressants, be particularly aware of serotonin syndrome symptoms, as this is a common cause of the condition, especially when used with other medications that increase serotonin levels. If you have questions about your medications or symptoms, call your healthcare provider or pharmacist. If you notice symptoms or if your symptoms worsen, call your healthcare provider right away or go to an emergency room.
Last reviewed on 03/24/2022.
Learn more about the Health Library and our editorial process.
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Cleveland Clinic is a non-profit academic medical center. Advertising on our site helps support our mission. We do not endorse non-Cleveland Clinic products or services. Policy