A possible tetracycline-risperidone-sertraline interaction in an adolescent.

A 15-year-old adolescent male, with Asperger's disorder, Tourette's disorder and obsessive-compulsive disorder, on a tetracycline-risperidone-sertraline treatment regimen, had an acute exacerbation of motor and vocal tics. The increase in tics may have resulted from either a tetracycline-risperidone interaction leading to decreased levels of risperidone, or a tetracycline-sertraline interaction leading to increased levels of sertraline or the natural course of the Tourette's disorder. The sertraline dose was increased with no concomitant increase in tics, and subsequent discontinuation of tetracycline resulted in an improvement in tics, which indicates an interaction between tetracycline and risperidone. The addition of antibiotics to psychotropic medications requires close monitoring due to the potential interactions.