Commonly used anticholinergic drugs include Benztropine: 0.5 mg at night up to 1 mg 2 times a day to 2 mg 3 times a day Trihexyphenidyl: 1 mg 3 times a day up to 2 to 5 mg 3 times a day Antihistamines with anticholinergic effects (eg, diphenhydramine 25 to 50 mg 2 to 4 times a day, or phenadrine 50 mg orally once to 4 times a day) are occasionally useful for treating tremor.