Diagnosis and treatment of serotonin syndrome

Serotonin syndrome is a drug-induced clinical syndrome caused by increased serotonin activity in the central nervous system. It occurs when starting a serotonergic drug, increasing its dose (including overdoses) or using a serotonergic drug in combination with other drugs. It manifests along a broad spectrum, ranging from mild side effects to life-threatening conditions. This condition should be suspected if patients have altered mental states, autonomic dysfunction, or neuromuscular symptoms such as clonus and tremor after using serotonergic drugs. Although the Hunter criteria have been widely used, new diagnostic criteria have recently been proposed to screen severe serotonin toxicity. It is necessary to differentiate it from neuroleptic malignant syndrome, which is associated with taking antipsychotic drugs that exert dopamine-antagonistic effects. If serotonin syndrome is suspected, the relevant drug should be stopped, and the patient should be treated with benzodiazepines. Severely ill patients with hyperthermia or neuromuscular symptoms require aggressive treatment. Serotonin receptor antagonists such as cyproheptadine or chlorpromazine have been tried as antidotes, but the level of evidence for their therapeutic effectiveness is very low.