Benztropine Side Effects

Some side effects of benztropine may not be reported. Always consult your doctor or healthcare specialist for medical advice. You may also report side effects to the FDA.

For the Consumer

Applies to benztropine: oral tablet

Get emergency medical help if you have any of these signs of an allergic reaction while taking benztropine: hives; difficulty breathing; swelling of your face, lips, tongue, or throat.

Call your doctor at once if you have a serious side effect such as:

• pounding heartbeats or fluttering in your chest;

• feeling very weak;

• feeling too weak to move;

• confusion, hallucinations, unusual thoughts or behavior;

• urinating less than usual or not at all;

• severe constipation;

• dry mouth that interferes with speech, swallowing, appetite, or eating;

• feeling very thirsty or hot, being unable to urinate, heavy sweating, or hot and dry skin;

• blurred vision, eye pain, or seeing halos around lights; or

• twitching or uncontrollable movements of your eyes, lips, tongue, face, arms, or legs.

Less serious side effects of benztropine may include:

• depressed mood, memory problems;

• drowsiness, feeling nervous or excited;

• nausea, upset stomach;

• dry mouth (mild);

• double vision, increased sensitivity to light; or

• numbness in your fingers;

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects.

For Healthcare Professionals

Applies to benztropine: compounding powder, injectable solution, oral tablet

General

General side effects have included symptoms related to its pharmacologic activity and are anticholinergic or antihistaminic in nature. Elderly patients and those with underlying organic brain disease tend to be the most susceptible, especially to the central effects.

Gastrointestinal

Gastrointestinal side effects have included dry mouth, difficulty swallowing, anorexia, constipation, nausea, and vomiting. A reduction in dosage will sometimes help alleviate these problems. Paralytic ileus may develop, particularly in patients on concomitant phenothiazine or tricyclic antidepressant therapy, and may occasionally be fatal. Upon withdrawal of medication, nausea and vomiting may occur due to a cholinergic rebound.

Nervous system

Nervous system side effects have included depression, anxiety, listlessness, drowsiness, numbness of fingers and dyskinesia. Benztropine may also aggravate symptoms of tardive dyskinesia or elicit previously suppressed symptoms. Sleepwalking has been attributed to drugs or combination of drugs with anticholinergic activity, including benztropine.

Cognitive deficits, such as impairment of recent and short-term memory and inability to concentrate, may occur with clinical doses of anticholinergic agents and may be dose-related.

Bucco-linguo-masticatory dyskinesias and chorea have been reported mostly in elderly patients being treated for Parkinson's disease with various anticholinergic agents. An isolated case of acute dystonic and dyskinesic reactions without evidence of anticholinergic toxicity has been described in a 20-month-old child following accidental ingestion of benztropine.

Psychiatric

Psychiatric side effects have included toxic psychosis. It may develop at toxic and therapeutic dosages with symptoms of confusion, disorientation, agitation, excitation, memory impairment, delusions and hallucinations (usually visual, but may be auditory or tactile or all three). Psychiatric deterioration and psychotic flare-ups have also been reported following withdrawal of therapy. Symptoms include delusions, hallucinations, aggression or violent behavior, and suicidal tendencies. In high dosages, benztropine may sometimes produce euphorigenic effects. For this reason, it can be a drug of abuse.

Toxic psychosis, when present, tends to occur quickly, generally within several days to a week of initiating benztropine therapy or within hours after an acute overdose. However, occasionally the onset may be delayed by months. The route of administration may be of some importance. One case report described several patients who developed psychosis after receiving benztropine by intramuscular injection. In any case, symptoms generally resolve spontaneously within a few days after the discontinuation of medication.

Ocular

Ocular side effects have included blurred vision, mydriasis, and cycloplegia. Cycloplegia may be marked when benztropine is used with neuroleptic agents, resulting in a reduction in near visual acuity.

Cardiovascular

Cardiovascular side effects have included tachycardia. An isolated case of sinus bradycardia has been reported.

Genitourinary

Genitourinary side effects have included urinary retention and dysuria.

Hypersensitivity

Hypersensitivity side effects have been reported occasionally. These have included skin rash.

Skin rash reactions may be controlled by dosage reduction. If no symptom control is obtained after dosage reduction, the medication should be discontinued.

Metabolic

Metabolic side effects have included alterations in the body's thermal homeostasis due to benztropine's inhibition of the body's sweating mechanism. Heat stroke, hyperthermia, and fever have occurred, most commonly in patients on concomitant neuroleptic or tricyclic antidepressant therapy.

Other

Anticholinergic poisoning syndrome may persist for more than a week's duration following benztropine overdose. One case report described fluctuating benztropine serum levels during this time, suggesting a prolonged and erratic absorption of the drug possibly due to its effects on gastrointestinal motility. In addition, benztropine may be eliminated slowly in the body or undergo enterohepatic circulation, accounting for its apparent lengthy duration of action.

Most patients with anticholinergic intoxication require only supportive therapy of vital functions and/or discontinuation of medications. However, severely agitated, delirious, or comatose patients may be treated with physostigmine salicylate, an acetylcholinesterase inhibitor with both central and peripheral effects.

Anticholinergic intoxication may present with central and peripheral symptoms including those listed above, in addition to warm and dry skin, EKG abnormalities, insomnia, twitching or jerking movements, pantomime activity with nonexistent objects, hyperactivity, hyperreflexia, respiratory arrest, delirium, convulsions, shock and coma.

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