Doxepin at higher doses is listed as anticholinergic. Which dose is flagged?

• A. >6 mg
• B. <6 mg
• C. Any dose
• D. Only in combination

Answer: (A)

Doxepin’s anticholinergic effects increase as the dose rises because it blocks muscarinic receptors more at higher amounts. The safety labeling flags doses above a certain threshold, specifically more than 6 mg daily, as anticholinergic. This matters because higher anticholinergic burden can cause dry mouth, constipation, urinary retention, confusion, and delirium—risks that are especially important in older adults or those with cognitive issues. At doses at or below 6 mg, the anticholinergic impact is much less, which is why only higher doses are flagged. The other options don’t fit because the anticholinergic risk isn’t present at any dose, it isn’t limited to combination therapy, and it isn’t restricted to doses below 6 mg.