Choreoathetosis induced by cyproheptadine.

Cyproheptadine is an antihistamine with antiserotoninergic and anticholinergic properties. It is a relatively safe drug with many varied indications for usage, which rarely produces serious adverse neurologic sequelae. Reports of involuntary movement disorder secondary to cyproheptadine are rare. We present the case of a 17-year-old overdose victim which may be the first documented instance of cyproheptadine intoxication resulting in choreoathetosis. This hyperkinesia was most likely resultant from the anticholinergic properties of cyproheptadine. Although the choreoathetoid movement resolved spontaneously, the delirious state disappeared after administration of physostigmine.