Serotonin Syndrome Causes, Symptoms and Treatment

Causes, Symptoms and Treatment

Serotonin Syndrome
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Serotonin syndrome, also known as hyperserotonemia or serotonergic syndrome, is a potentially life-threatening condition in which there is an excess of serotonin in the central nervous system.

What Causes It?

Serotonin syndrome may be caused by use of high doses of serotonergic drugs, combination of more than one serotonergic drug or when antidepressants are switched without allowing for a "washout" period.

Drugs Which May Contribute to Serotonin Syndrome

Antidepressants, opioids, CNS stimulants, 5-HT1 agonists, certain illegal drugs, selegiline, tryptophan, buspirone, lithium, linezolid, dextromethorphan, 5-HTP and chlorpheniramine may all contribute to serotonin syndrome.

Among antidepressants, MAOIs are of particular concern. MAOIs permanently inhibit monoamine oxidase so the enzyme cannot function until more is produced by the body. Serotonin agonists and even foods containing the serotonin precursor tryptophan must be stricly avoided.

How Is It Diagnosed?

There is no test for serotonin syndrome so it must be diagnosed based upon symptoms. Symptoms are divided into three categories:

  • Cognitive effects: mental confusion, hypomania, agitation, headache, coma.
  • Autonomic effects: shivering, sweating, fever, hypertension, tachycardia, nausea, diarrhea.
  • Somatic effects: myoclonus/clonus, hyperreflexia, tremor.

    Sleep disturbances, itching and hives may also be reported.

    Anyone experiencing these symptoms should seek medical care immediately.

    Serontonin Syndrome Treatment

    There is no known antidote to serotonin syndrome. Treatment consists of discontinuing the offending medication(s) and administering care to control the symptoms.

    Serotonin antagonists such as cyproheptadine or methysergide may be given as well as benzodiazepines, which can relieve muscle rigidity. In acute cases, mechanical ventiliation may be necessary. Once the medication is stopped the condition will generally resolve itself, most often in 24 hours, although it may take up to 96 hours.


    "Mental Health Book/Pharmacology Chapter/Serotonin Syndrome." Family Practice Notebook. Family Practice Notebook, LLC.  Accessed:  October 13, 2015.

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