Which of the following drug categories is known to affect salivary flow?

• A. Antihistamines
• B. Antidepressants
• C. Antibiotics
• D. Vitamins

Answer: (A)

Salivary flow is reduced by many medications that have anticholinergic effects, which suppress the glands’ ability to produce saliva. Antihistamines commonly cause dry mouth because they block muscarinic receptors and lower saliva secretion. When saliva decreases, its buffering and cleansing actions are diminished, allowing acids to linger longer and promote demineralization, increasing caries risk. Other options like antibiotics and vitamins don’t routinely reduce saliva flow as a primary effect, though some antidepressants can cause dry mouth too via anticholinergic activity; antihistamines remain the most consistently associated with reduced salivary flow among the listed categories.