Drug-induced sialorrhea.

Only a few drugs can induce drooling (sialorrhea or hypersalivation) to a clinically significant degree. When significant drooling occurs, however, it can pose a vexing management problem. Drooling is either caused by an increase in saliva flow that cannot be compensated for by swallowing, or by impaired swallowing that cannot handle normal or even reduced amounts of saliva. Major medication groups that are clearly associated with drooling are antipsychotics, particularly clozapine, and direct and indirect cholinergic agonists that are used to treat dementia of the Alzheimer type and myasthenia gravis. Drooling is also caused by certain heavy metal toxins (mercury and thallium); from exposure to irreversible acetylcholinesterase inhibitors (insecticides and nerve agents); and by a handful of other drugs (e.g., yohimbine, mucosa-irritating antibiotics). The treatment of medication-induced drooling is often only symptomatic and attempts to decrease saliva to amounts that can be swallowed (to prevent "pool and drool"). Most pharmacological approaches reduce cholinergic tone, either systemically (e.g., atropine-related oral anticholinergics) or more locally (e.g., sublingual ipratropium spray); or increase adrenergic tone (e.g., clonidine patch). Recently, botulinum injections into the parotid gland have been used successfully to treat refractory cases.