What are common adverse effects of antimuscarinic therapy?

• A. Dry mouth, constipation, urinary retention risk, blurred vision, and cognitive effects in older adults
• B. Hyperkalemia and hypertension
• C. Weight gain and hair loss
• D. Drowsiness only

Answer: (A)

Antimuscarinic therapy works by blocking acetylcholine at muscarinic receptors, which decreases involuntary bladder contractions but also reduces parasympathetic activity in several tissues. The most common adverse effects come from this widespread anticholinergic action: dry mouth from reduced salivation, constipation from slowed gut motility, risk of urinary retention from detrusor relaxation, blurred vision due to pupil dilation and impaired accommodation, and cognitive or delirium-like effects in older adults from central nervous system receptor blockade. These effects are the hallmark of antimuscarinic drugs and explain why this option best matches what is typically seen in practice. The other choices describe effects that aren’t characteristic of antimuscarinics—hyperkalemia and hypertension, or weight changes, or drowsiness alone—so they don’t fit as well with the common adverse effect profile.