What is a side effect of diphenhydramine?

A. Salivation: Diphenhydramine, an antihistamine with anticholinergic properties, typically reduces salivation rather than increases it. Excessive drooling is not a side effect of this medication. B. Watery eyes: Diphenhydramine works to relieve allergic symptoms, including watery eyes, so this symptom is more likely to be a reason for taking the medication rather than a side effect. C. Urinary frequency: Anticholinergic effects of diphenhydramine usually cause urinary retention, not increased frequency. Clients may experience difficulty voiding rather than needing to urinate more often. D. Constipation: The anticholinergic action of diphenhydramine can slow gastrointestinal motility, leading to constipation. Clients should be advised about this potential side effect and strategies to prevent it, such as increased fluid and fiber intake.