Walsh & Hoyt: Drug Effects on Lacrimation

Lacrimation may be altered by the effects of topical and systemic agents on the main lacrimal gland, its nerve supply, or the accessory lacrimal glands. Some drugs, including methacholine and pilocarpine, induce tearing by direct parasympathomimetic action on the secretory cells of the lacrimal gland. Topical drug effects must be differentiated from tearing produced through corneal irritation, local allergic reaction, and so forth. The number of agents that reduce tear secretion is small; they include psychotropic drugs and practolol.