What Is Serotonin Syndrome?
Serotonin syndrome is a condition that can occur after taking certain medicines. It is not common but it can be serious or fatal when it happens.
It is unknown why some people develop serotonin syndrome and others do not, but it usually happens within 6 to 24 hours of taking a new medication, a higher dose, or a new combination of drugs.
What Are Symptoms of Serotonin Syndrome?
Symptoms of serotonin syndrome include:
- Muscle spasms
- Continuous back-and-forth eye movements
- Dilated pupils
- Shaking or trembling (tremor)
- Fast heartbeat
- Increased bowel sounds
- Flushed skin
Severe symptoms of serotonin syndrome include:
When to seek medical attention
- If you or someone you know experience severe symptoms, go to the emergency room (do not drive yourself) or call 911.
- Mild cases of serotonin syndrome may last for four to six hours. In general, symptoms of serotonin syndrome usually resolve within 24 hours of discontinuing the drug that caused the condition and starting medical care, but drugs with long durations of action or active metabolites may cause prolonged symptoms.
What Causes Serotonin Syndrome?
Serotonin syndrome occurs after people take certain medicines or combinations of medicines, or certain herbal products and street drugs. These drugs cause an increase the neurotransmitter in the brain and body called serotonin. When the levels of serotonin become too high, serotonin syndrome can occur.
Some medicines and drugs that can cause serotonin syndrome include:
- Selective serotonin reuptake inhibitor (SSRI) antidepressant
- Medicines used to treat Parkinson disease, such as selegiline (Eldepryl, Emsam) and rasagiline (Azilect)
- Some pain relievers, such as meperidine (Demerol), tramadol (Ultram), fentanyl, and cyclobenzaprine (Flexeril
- Saint John's wort (an herbal supplement)
- Migraine headache medications called “triptans”
- Some medicines used to treat attention deficit hyperactivity disorder (ADHD)
- The linezolid (Zyvox)
- The cough medicine dextromethorphan (Delsym, Robitussin DM)
- Street drugs, such as ecstasy, cocaine, and amphetamines
How Is Serotonin Syndrome Diagnosed?
There is no single test used to diagnose serotonin syndrome. A doctor will ask about any medicines, herbal products, or street drugs you might have taken. It's important to be honest with the doctor about what you took, how much, and when it was taken so you can be properly treated.
Tests may be needed to rule out other conditions that may be causing the symptoms, and also to monitor for potential complications, especially in severely ill patients, such as:
- Blood tests
- Imaging tests
- Chest X-ray
- Head computed tomography (CT) scan
- Urinalysis and urine culture
- Cerebrospinal fluid analysis and culture
What Is the Treatment for Serotonin Syndrome?
Treatment for serotonin syndrome involves stopping the medicines or drugs that were responsible for causing the serotonin syndrome under medical supervision. Breathing, heart rate, blood pressure, and body temperature will be monitored.
Other treatments for serotonin syndrome may include:
- Sedation with benzodiazepines
- Administration of serotonin antagonists to block the effects of the serotonin
- Assessing the need to resume use of the drugs that caused the symptoms once the symptoms have gone away
Patients with severe serotonin syndrome (e.g., hyperthermia, autonomic instability, agitated delirium) will likely require care in a hospital’s intensive care unit (ICU).
How Do You Prevent Serotonin Syndrome?
Serotonin syndrome cannot always be prevented but you may be able to lower the risk of developing the condition.
- Tell any doctor who prescribes medicines for you about all the medicines, herbal products, and street drugs you use so the doctor can ensure you are not prescribed any medications that could cause problems if combined
- Talk to your doctor, pharmacist, or other healthcare professional before taking any new over-the-counter medicines, supplements, or herbs
- Have the pharmacist check for drug interactions for any new medications you are prescribed, or any new over-the-counter medicines, supplements, or herbs you plan to take
- Have your healthcare providers regularly review your medications list to ensure it is correct
- Make sure the medications are correct, in the proper doses, and that you are not taking any medicine you were supposed to stop
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