What is serotonin syndrome and which drug combinations commonly cause it?

• A. A mild allergic reaction.
• B. Serotonin syndrome is a mood disorder.
• C. Potentially life-threatening hyperthermia, agitation, hyperreflexia; due to combinations of SSRIs with MAO inhibitors or SNRIs or tricyclics; discontinue and provide supportive care.
• D. A withdrawal syndrome.

Answer: (C)

Serotonin syndrome is a potentially life-threatening reaction caused by too much serotonin activity in the brain and body. It usually happens when drugs that raise serotonin levels are combined, such as an SSRI with a monoamine oxidase inhibitor, or when an SSRI is taken along with other serotonergic meds like SNRIs or TCAs. The onset is rapid after starting or changing a medication.

The warning signs span three areas: mental status changes (anxiety, agitation, confusion), autonomic symptoms (high heart rate, high blood pressure, fever, sweating), and neuromuscular abnormalities (tremor, hyperreflexia, clonus). Because the risk of serious complications is real, the primary step is to stop the offending drugs and provide supportive care. This can include cooling measures and IV fluids, with benzodiazepines for agitation or tremor. In more severe cases, a serotonin receptor antagonist such as cyproheptadine may be used. This syndrome is distinct from withdrawal and from other conditions like neuroleptic malignant syndrome, and prompt recognition and management are key.