Final answer:
Anticholinergic drugs have an anticholinergic side effect that can contribute to urinary retention in the elderly.
Step-by-step explanation:
The class of medications that has an anticholinergic side effect that can be problematic in the elderly because it can contribute to urinary retention is anticholinergic drugs. Anticholinergic drugs work by blocking the action of acetylcholine, a neurotransmitter responsible for various bodily functions including urine control. By blocking acetylcholine, anticholinergic drugs can cause relaxation of the bladder muscles and lead to urinary retention.