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Serotonin syndrome (SS) is a reaction caused by medicines that increase the levels of serotonin in the nervous system. It is potentially fatal. 

Signs and symptomsEdit

Its symptoms include: diarrhoea, tachycardia, shivering, sweating, hypertension, mydriasis (dilated pupils), mental status changes (including mania, confusion, agitation, hyperactivity, restlessness and psychosis), seizures, coma, tremor, incoordination, hyperthermia, etc. Most fatalities are due to rhabdomyolysis, disseminated intravascular coagulation, respiratory distress syndrome or severe hyperthermia.[1]


It is most commonly precipitated by more than one medicine that acts on serotonin being given at once. Known causes include those listed in table 1.

Table 1: Causes for SS
Class of drug Examples[2][3][4][5]
Analgesics (painkillers) Buprenorphine, cyclobenzaprine, dextropropoxyphene, fentanyl, hydrocodone, morphine, oxycodone, pentazocine, pethidine (or meperidine), tapentadol and tramadol.
Antidepressants MAOIs, NaSSAs, NDRIs, SARIs, SNRIs and SSRIs.
Antiemetics 5-HT3 antagonists (blockers) such as granisetron and ondansetron; D2 antagonists such as droperidol and metoclopramide.
Anti-migraine medicines Triptans (e.g., sumatriptan) and ergotamines (e.g., dihydroergotamine).
Antipsychotics Olanzapine, reserpine and risperidone.
Illicit drugs MDMA, 5-MeO-DiPT (“foxy methoxy”), lysergide (LSD) and other psychedelics.
OTC and complimentary medicines Brompheniramine, chlorphenamine (or chlorpheniramine), dextromethorphan, Panax ginseng, St. John’s wort, S-adenosylmethionine (SAMe), Syrian rue and yohimbe.
Others 5-hydroxytryptophan, buspirone, carbamazepine (an anti-seizure medicine that is also used as a mood stabilizer), fluconazole, levodopa, linezolid, lithium, methylene blue, selegiline, tryptophan and valproic acid (an anti-seizure medicine that is also used as a mood stabilizer). Certain foods may contribute to SS, including cheese and red wine.
Stimulants Amfetamines (including dexamfetamine and metamfetamine), cocaine and methylphenidate
Weight loss medicines Amfepramone (diethylpropion), phentermine and sibutramine (no longer marketed).


SS is believed to be caused by excess stimulation of the 5-HT1A and/or 5-HT2 (especially 5-HT2A) receptors.[1]


Treatment usually consists of supportive measures (that is, managing the symptoms like hyperthermia) and treatment with serotonin antagonists (blockers). Amongst serotonin antagonists usually cyproheptadine is preferred, but sometimes chlorpromazine or propanolol may be used.


The prognosis for SS is generally favourable, provided the diagnosis is made early and the treatment is begun without delay.

External linksEdit

Reference listEdit

  1. 1.0 1.1 Hall, M; Buckley, N (June 2003). "Serotonin syndrome". Australian Prescriber (Strawberry Hills, Australia: National Prescribing Service) 26 (3): 62–63. 
  2. Boyer, EW; Shannon, M (2005). "The serotonin syndrome" (PDF). New England Journal of Medicine 352 (11): 1112–20. PMID 15784664. doi:10.1056/NEJMra041867. 
  3. "Prescribing Practice Review 32: Managing depression in primary care" (PDF). National Prescribing Service Limited. 2005. Retrieved 13 August 2014. 
  4. Iqbal, MM; Basil, MJ; Kaplan, J; Iqbal, MT (November 2012). "Overview of serotonin syndrome.". Annals of Clinical Psychiatry 24 (4): 310–8. PMID 23145389. 
  5. Volpi-Abadie, J; Kaye, AM; Kaye, AD (Winter 2013). "Serotonin syndrome.". The Ochsner Journal 13 (4): 533–40. PMC 3865832. PMID 24358002. 

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