Dry mouth, also known as xerostomia, is a common side effect of many medications. The category of medications most frequently associated with causing drug-induced dry mouth is anticholinergics.

Anticholinergic drugs work by blocking the action of acetylcholine on muscarinic receptors in the parasympathetic nervous system. Since acetylcholine is crucial for stimulating salivary gland secretion, this blockade leads to reduced saliva production and thus, dry mouth. This effect is more pronounced with medications that have strong anticholinergic properties.

While antihistamines and diuretics can also contribute to dry mouth, their mechanisms differ and are usually less significant compared to anticholinergics. Beta blockers are not commonly linked to dry mouth and are less likely to cause this side effect.

Understanding the role of anticholinergic activity is important for clinicians when prescribing medications, especially in populations vulnerable to xerostomia, such as the elderly, to help mitigate complications like dental caries, oral infections, and difficulty swallowing.

Reference: Goodman & Gilman’s The Pharmacological Basis of Therapeutics, 13th Edition, Chapter 10 / Page 256