Trihexyphenidyl works as an anticholinergic and is used for the treatment of tremors, spasms, stiffness, and weak muscle control seen in patients with Parkinson disease. It can also be used to prevent or treat similar muscular conditions which are caused by certain central nervous systems (CNS) drugs such as fluphenazine, haloperidol, and chlorpromazine. It was approved by FDA for the management of all types of parkinsonism (idiopathic, postencephalitic, and arteriosclerotic) in June 2003. This activity outlines the indications, mechanism of action, methods of administration, important adverse effects, contraindications, toxicity, and monitoring, of trihexyphenidyl so providers can direct patient therapy as indicated as part of the interprofessional team.