You’ve probably heard of serotonin. It’s a chemical produced by nerve cells in your brain that helps keep your mood balanced. Since it affects your mood, doctors often prescribe drugs called selective serotonin reuptake inhibitors (SSRIs) to treat depression by increasing your serotonin levels.
Serotonin syndrome (or serotonin toxicity) is a serious adverse drug reaction that can develop if you get too much serotonin in your system. “Symptoms can range from very mild to life threatening,” said Jerry Snow, MD, a toxicologist at Banner Health.
What are the symptoms of serotonin syndrome?
Symptoms of serotonin syndrome include:
- Altered mental status such as confusion or changes in your thinking
- Trouble sleeping
- Agitation or restlessness
- Increased heart rate and/or blood pressure
- Dilated pupils
- Tremors or shivering
- Goosebumps
- Sweating
- Headache
- Nausea, vomiting or diarrhea
- Muscle stiffness, spasms or twitching and involuntary muscle contractions
In severe cases of serotonin syndrome, you could experience:
- High body temperature
- Seizures
- Irregular heartbeat
- Loss of consciousness
What causes serotonin syndrome?
You could develop serotonin syndrome from using medications that affect your serotonin levels, interactions between drugs or overdose of certain drugs. “Many medications are associated with the syndrome,” Dr. Snow said. And they aren’t just drugs that treat depression or other mental health conditions. They include:
- Monoamine oxidase inhibitors (MAOIs)
- Tricyclic antidepressants
- Selective serotonin reupdate inhibitors (SSRIs)
- Opiate analgesics
- Over-the-counter cough and cold medications containing dextromethorphan
- Antibiotics
- Weight-reduction agents
- Drugs that reduce nausea or vomiting, called antiemetics
- Antimigraine medications
- Drugs of abuse
- Herbal products such as St. John’s Wort
- Serotonin and norepinephrine reuptake inhibitors (SNRIs)
You’re at higher risk for serotonin syndrome if you just started or increased a medication that raises serotonin levels or if you take more than one medication known to increase serotonin levels. It’s unlikely that you’ll develop serotonin syndrome if you’re taking just one drug and taking it as prescribed. “Even following an overdose of an SSRI, serotonin syndrome occurs in only 14 to 16% of people,” Dr. Snow said.
How can you prevent serotonin syndrome?
It’s crucial that you talk to your doctor or pharmacist about all your medications. That way, you can make adjustments if needed to avoid possible interactions. You might not think to mention cough medicine, dietary supplements or herbal products, but try not to overlook anything. “Avoiding the combination of multiple drugs is a critical step in prevention,” Dr. Snow said.
How is serotonin syndrome diagnosed?
There is no lab test that can confirm it, so doctors diagnose serotonin syndrome based on your medical history and a physical exam. If you have taken drugs that could cause serotonin syndrome in the last several weeks and you have tremors, increased reflexes and involuntary muscle contractions, your doctor may diagnose it.
How is serotonin syndrome treated?
To treat serotonin syndrome, your doctor may have you stop taking the drugs that cause it. For mild symptoms, stopping the medication or changing the dosage usually brings relief within 24 to 72 hours. You may need supportive care and intravenous fluids, and sedatives if you are agitated. Sometimes, doctors prescribe medications such as cyproheptadine or antipsychotic agents to counteract the serotonin. In severe cases, you could require intensive care.
What is the difference between serotonin syndrome and neuroleptic malignant syndrome (NMS)?
Serotonin syndrome and neuroleptic malignant syndrome (NMS) are serious medical conditions triggered by certain medications, but they have different causes and involve distinct types of drugs.SS arises from excessive serotonin levels due to medications like SSRIs and SNRIs, leading to symptoms such as agitation, rapid heartbeat, dilated pupils, sweating, tremors, and potentially seizures or loss of consciousness. NMS, however, is associated with antipsychotic medications, particularly older "typical" antipsychotics, causing symptoms like high fever, muscle rigidity, altered mental state, autonomic dysfunction, and severe complications such as kidney failure or cardiac arrhythmias. Although rare, it's crucial to differentiate between the two and seek immediate medical attention for accurate diagnosis and appropriate care.
The bottom line
Serotonin syndrome is a dangerous interaction caused by drugs that affect your serotonin level. Talk to your doctor about your medications to see if you're at risk. To find a doctor who can help you evaluate your prescription and over-the-counter drugs, reach out to Banner Health.
