A nurse is teaching a client about benztropine to treat their Parkinson's disease symptoms. The nurse should instruct the client to report which of the following adverse effects?

A. Excessive salivation: Benztropine is an anticholinergic medication that decreases parasympathetic activity, typically resulting in dry mouth rather than excessive salivation. Increased salivation is not expected and does not indicate a common adverse effect of this drug. B. Difficulty voiding: Anticholinergic effects of benztropine can inhibit detrusor muscle contraction and reduce bladder tone, leading to urinary retention or difficulty voiding. This is a significant adverse effect that should be reported promptly, as it may require intervention to prevent complications such as bladder distention or infection. C. Diarrhea: Benztropine generally decreases gastrointestinal motility and secretions due to its anticholinergic properties. Clients are more likely to experience constipation rather than diarrhea, making diarrhea an unlikely adverse effect of concern with this medication. D. Decreased heart rate: Anticholinergic medications like benztropine can actually cause tachycardia by blocking parasympathetic influences on the sinoatrial node. Bradycardia or decreased heart rate is not typically associated with benztropine use and is not an expected adverse effect to report.