Which of the following side effects is least likely to be associated with anticholinergic medications?

Anticholinergic medications primarily block the action of acetylcholine at muscarinic receptors, which leads to a variety of side effects due to their inhibitory effects on the parasympathetic nervous system. Common side effects associated with anticholinergic medications include blurred vision, dry mouth, and constipation, all of which stem from reduced secretion and muscle tone in various body systems.

Blurred vision occurs because anticholinergic agents can cause paralysis of the ciliary muscle of the eye, which impairs the ability to focus (a condition known as cycloplegia). Dry mouth is a frequent complaint as these agents reduce salivary gland secretion, leading to xerostomia. Constipation arises due to decreased gut motility because anticholinergics inhibit peristalsis in the gastrointestinal tract.

In contrast, excessive sweating, known as hyperhidrosis, is generally a sympathetic response rather than a parasympathetic one. Anticholinergics tend to decrease sweating by inhibiting the cholinergic innervation of sweat glands. As a result, excessive sweating is not a common side effect associated with anticholinergic medications, making it the least likely to occur when taking these drugs.