Worst Pills, Best Pills

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Drug Profile

Do NOT stop taking this or any drug without the advice of your physician. Some drugs can cause severe adverse effects when they are stopped suddenly.

Do Not Use [what does this mean?]
Generic drug name: benztropine (BENZ troe peen)
Brand name(s): COGENTIN
GENERIC: not available FAMILY: Drugs for Parkinson’s Disease
Find the drug label by searching at DailyMed.

Do Not Use [what does this mean?]
Generic drug name: trihexyphenidyl (tri hex ee FEN i dill)
Brand name(s):
GENERIC: not available FAMILY: Drugs for Parkinson’s Disease
Find the drug label by searching at DailyMed.

Alternative Treatment [top]

Safety Warnings For This Drug [top]

Anticholinergic Effects

Warning: Special Mental and Physical Adverse Effects

Older adults are especially sensitive to the harmful anticholinergic effects of these drugs. Drugs in this family should not be used unless absolutely necessary.

Mental Effects: confusion, delirium, short-term memory problems, disorientation and impaired attention

Physical Effects: dry mouth, constipation, difficulty urinating (especially for a man with an enlarged prostate), blurred vision, decreased sweating with increased body temperature, sexual dysfunction and worsening of glaucoma

Benztropine and trihexyphenidyl are appropriate drugs to manage the drug-induced movement disorders that may be seen with the use of drugs for treating serious mental illness.

Facts About This Drug [top]

Trihexyphenidyl and benztropine are approved by the FDA for the symptoms of Parkinson’s disease and to manage the drug-induced movement disorders that may result from some of the drugs used to treat serious mental illness.

Drugs like trihexyphenidyl and benztropine, also known as anticholinergics, were the first drugs available for the symptomatic treatment of Parkinson’s disease.[1]

These drugs should not be used to treat Parkinson’s disease because they can cause several serious antichol...

Trihexyphenidyl and benztropine are approved by the FDA for the symptoms of Parkinson’s disease and to manage the drug-induced movement disorders that may result from some of the drugs used to treat serious mental illness.

Drugs like trihexyphenidyl and benztropine, also known as anticholinergics, were the first drugs available for the symptomatic treatment of Parkinson’s disease.[1]

These drugs should not be used to treat Parkinson’s disease because they can cause several serious anticholinergic adverse effects—more frequently in older adults. These effects include memory impairment, confusion, hallucinations, and retention of urine.

A major statistical summary of clinical trials, known as a meta-analysis, concluded: “As monotherapy or as an adjunct to other antiparkinsonian drugs, anticholinergics are more effective than placebo in improving motor function in Parkinson’s disease. Neuropsychiatric and cognitive adverse events occur more frequently on anticholinergics than on placebo and are a more common reason for withdrawal than lack of efficacy.”[1]

An Australian review of treating Parkinson’s disease in older patients concluded: “Anticholinergic drugs such as benztropine and benzhexol [British generic name for trihexyphenidyl] are best avoided because of the high risk of major side effects.”[2]

In 2015, a study published in JAMA Internal Medicine showed that strong anticholinergic drugs were associated with an increased risk of dementia in older adults. The study also showed that higher doses and longer use of these drugs are associated with higher risk of dementia.[3]

Refer to the August 2015 issue of Worst Pills, Best Pills News for examples of strong anticholinergic drugs.

If you have symptoms of parkinsonism (tremor, rigid muscles, and disturbances in posture, walking, balance, speech, swallowing, and muscle strength), there is a good chance that they are caused by a drug you are taking. As many as half of older adults with symptoms of parkinsonism may have developed them as adverse effects of a drug. (See the section of this web site that lists drugs that can cause symptoms of parkinsonism.) If you take any of the drugs on this list, discuss the possibility of drug-induced parkinsonism with your doctor and ask to have your prescription changed or stopped.

last reviewed June 30, 2021