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Benztropine Side Effects

In Summary

More frequently reported side effects include: drowsiness, nausea and vomiting, constipation, visual disturbance, urinary hesitancy, dry mucous membranes, and hypohidrosis. See below for a comprehensive list of adverse effects.

For the Consumer

Applies to benztropine: oral solution, oral tablet

Other dosage forms:

In addition to its needed effects, some unwanted effects may be caused by benztropine. In the event that any of these side effects do occur, they may require medical attention.

Severity: Major

You should check with your doctor immediately if any of these side effects occur when taking benztropine:

Incidence not known:
  • Abdominal or stomach cramps or pain
  • aggressive and violent behavior
  • being forgetful
  • bloating
  • burning while urinating
  • confusion about identity, place, and time
  • constipation
  • decrease in frequency of urination
  • decrease in urine volume
  • diarrhea
  • difficult or painful urination
  • difficulty in passing urine (dribbling)
  • difficulty with speaking
  • difficulty with swallowing
  • discouragement
  • dizziness
  • dry mouth
  • extremely high fever or body temperature
  • fast, pounding, or irregular heartbeat or pulse
  • fast, shallow breathing
  • fast, weak heartbeat
  • feeling sad or empty
  • fever
  • headache
  • hot, dry skin
  • irritability
  • lack of appetite
  • lack of sweating
  • listlessness
  • loss of interest or pleasure
  • mood or mental changes
  • muscle cramps
  • muscle weakness
  • nervousness
  • numbness of the fingers
  • pale, clammy skin
  • seeing things that are not there
  • thirst
  • tiredness
  • trouble concentrating
  • trouble with sleeping
  • vomiting

If any of the following symptoms of overdose occur while taking benztropine, get emergency help immediately:

Symptoms of overdose:
  • Blindness
  • blurred vision
  • change in consciousness
  • cold clammy skin
  • decreased vision
  • dizziness
  • eye pain
  • holding false beliefs that cannot be changed by fact
  • lightheadedness
  • loss of consciousness
  • muscle weakness
  • nausea or vomiting
  • no breathing
  • nosebleeds
  • numbness or tingling in the face, arms, or legs
  • shakiness and unsteady walk
  • sweating
  • tearing
  • unsteadiness, trembling, or other problems with muscle control or coordination
  • unusual excitement, nervousness, or restlessness
  • vision problems
  • wheezing

Severity: Minor

Some of the side effects that can occur with benztropine may not need medical attention. As your body adjusts to the medicine during treatment these side effects may go away. Your health care professional may also be able to tell you about ways to reduce or prevent some of these side effects. If any of the following side effects continue, are bothersome or if you have any questions about them, check with your health care professional:

Incidence not known:
  • Enlarged pupils
  • loss of appetite
  • skin rash
  • weight loss

For Healthcare Professionals

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


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.[Ref]


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.[Ref]

Nervous system

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.[Ref]

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.[Ref]


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.[Ref]

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.[Ref]


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.[Ref]


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


Genitourinary side effects have included urinary retention and dysuria.[Ref]


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

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


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.[Ref]


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.[Ref]

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.[Ref]


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Not all side effects for benztropine may be reported. You should always consult a doctor or healthcare professional for medical advice. Side effects can be reported to the FDA here.

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