Abstract
Introduction:
The use of topiramate has increased in recent years. It is now used by various specialties to treat a wide range of medical conditions. A small number of case reports describe psychosis as an adverse event of topiramate but most are in patients being treated for epilepsy and none describe a family history of this side effect.

Case presentation:
We present a case report of topiramate-induced psychosis in a patient with familial essential tremor, whose sister also developed this same adverse effect.

Conclusion:
Physicians need to be aware of psychosis as a rare but debilitating side effect of this drug. Several predictors have been identified and a careful history, including family history, needs to be obtained prior to initiation of therapy to stratify the risk.