SEROTONERGIC SYMPTOMS - Symptoms that are caused by overactivity of neurotransmitter serotonin in the brain. These include altered mental status (e.g. agitation, delirium, coma), autonomic dysfunction (e.g. salivation, sweating, hyperthermia, tachycardia, dilated pupils, fluctuations in blood pressure), and neuromuscular abnormalities (e.g. tremor, rigidity, myoclonus, seizures).