Benztropine is frequently given concurrently with haloperidol. benztropine is used to:

Benztropine, short for benztropine mesylate, is an anticholinergics used to treat muscle stiffness and muscle spasms in the back, neck and eye movements. These medications work by hindering the production of the hormone acetylcholine. By doing so, you prevent the production of saliva, spasms and excessive sweating. Benztropine is a generic term for drugs like cogentin. Its common use is for treating symptoms of patients with Parkinson's disease. Other scenarios would be treating side effects of antipsychotic drugs.

However, there are also its own side effects of taking benztropine. These include nausea, vomiting and constipation.