Serotonin syndrome is an uncommon, serious adverse reaction that is usually
associated with the interaction of two or more serotonergic agents. A 12-y
ear-old boy receiving sertraline developed the syndrome after erythromycin
was added to his regimen. The proposed mechanism involves erythromycin inac
tivation of cytochrome P450 3A4 inhibition of sertraline metabolism, accumu
lation of the drug, and precipitation of the syndrome. It is important for
clinicians to consider both pharmacokinetic and pharmacodynamic interaction
s to minimize the risk of the reaction.