• The spectrum of ‘serotonin toxicity’ relates to a form of poisoning, not an idiosyncratic reaction.  It progresses from mild to life-threatening toxicity, with increasing intrasynaptic serotonin levels.

 
• Serotonin syndrome is due to a toxic hyperserotonergic state from hyperstimulation of the brain stem and spinal cord 5HT1A and 5HT2 receptors, possibly with more involvement of the latter.

• Serotonin syndrome can occur from an overdose, drug interaction or even single drug therapy in susceptible individuals with a serotonergic agent.

• Symptoms consist of alteration of mental status, neuromuscular hyperactivity and autonomic instability.  Patients do not necessarily have all three features.

• The Hunter diagnostic criteria include clonus which is more specific to serotonin toxicity.

• Medicines potentially causing serotonin syndrome all have some form of serotonergic activity.