Serotonin Syndrome
Excess stimulation of central and peripheral serotonin receptors from serotonergic drug combinations produces a rapid-onset triad of neuromuscular, autonomic and mental-state disturbance that resolves once the receptor drive is removed or blocked.
First principles
One receptor effect, three locations, one triad
Combining or overdosing on serotonergic drugs floods central and peripheral 5-HT receptors, particularly 5-HT2A, producing a hyperserotonergic state. The clinical triad is not three unrelated findings but the same excess receptor activity expressed wherever those receptors sit: spinal motor neurons produce neuromuscular hyperactivity (clonus, hyperreflexia, tremor), hypothalamic and brainstem autonomic centres produce autonomic instability (hyperthermia, tachycardia, diaphoresis, diarrhoea), and cortical/limbic circuits produce altered mental state (agitation, confusion).
Educational content pending clinical review. Not medical advice.