Rationale for avoiding antihistamines in older adults includes which of the following?

• A. They are not effective in older adults
• B. They do not have anticholinergic effects
• C. They have highly anticholinergic activity and clearance declines with age
• D. They are rarely used due to cost

Answer: (C)

Antihistamines, especially the older, first-generation ones, carry strong anticholinergic activity, and in older adults the body's ability to clear these drugs declines with age. This combination means longer exposure to anticholinergic effects, which can worsen confusion, delirium, constipation, urinary retention, dry mouth, and other cognitive or functional issues. That heightened risk is the reason these drugs are avoided in older adults according to the Beers Criteria.

The other statements aren’t correct because first-generation antihistamines do have significant anticholinergic effects, and while cost can influence some prescribing decisions, it isn’t the primary reason they’re avoided in this context.