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Anticholinergic toxicity — USMLE Step 3 MCQ

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HardAmbulatory Medicine / Primary CareAnticholinergic toxicityUSMLE Step 3

A 76-year-old man has dry mouth, constipation, urinary hesitancy, and confusion after starting an over-the-counter sleep aid. Pupils are mildly dilated and mucous membranes are dry. Other medications are lisinopril and atorvastatin. Which of the following is the most likely explanation for this patient's findings?

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Correct answer: A — Anticholinergic adverse effect

First-generation antihistamine sleep aids can cause anticholinergic toxicity, particularly in older adults.

Reference: Current US clinical practice standards and USMLE Step 3 content outline, https://www.usmle.org/exam-resources/step-3-materials