Which medication should be used cautiously in elderly due to risk of confusion and constipation?

• A. Diphenhydramine
• B. Loratadine
• C. Cetirizine
• D. Fexofenadine

Answer: (A)

Anticholinergic burden in the elderly is a key factor: meds with strong anticholinergic effects can cause confusion and constipation because aging brains are more sensitive to these effects and drug clearance is often reduced. Diphenhydramine is a first-generation antihistamine with significant anticholinergic activity and it crosses into the brain easily, which can lead to delirium, confusion, dry mouth, urinary retention, and constipation in older adults. Because of this risk, it should be used cautiously in the elderly. The other options are second-generation antihistamines with much lower central nervous system penetration and weaker anticholinergic effects, making them safer choices with regard to confusion and constipation in older patients.