Final answer:
A possible adverse effect of using a first-generation antihistamine like diphenhydramine in an older adult is urinary retention. This is due to the anticholinergic effects of such medications, which can lead to difficulty in urination, especially in men with an enlarged prostate.
Step-by-step explanation:
A possible adverse effect with the use of a first-generation antihistamine such as diphenhydramine in an 80-year-old man is: A. Urinary retention. First-generation antihistamines can have anticholinergic effects which may lead to difficulty in urinating, especially in older men who may have an enlarged prostate. These antihistamines, such as diphenhydramine, act on H₁ receptors but can also affect other receptors in the body leading to side effects.
Diphenhydramine can cause various side effects, but urinary retention is particularly concerning in elderly individuals due to the risk of urinary tract infections and bladder issues. This drug does not typically cause hypertension, tachycardia, or urticaria; in fact, antihistamines are used to treat allergic reactions such as urticaria.
It is important to know that antihistamines can have multiple effects beyond treating allergy symptoms, such as preventing the itch and swelling produced by histamines. In addition, consultation of a medical professional is recommended for those who intend to take antihistamines for longer-term use, particularly in the elderly population.