A common side effect of clozapine is drooling or the appearance of excess saliva, also known as sialorrhea. This is caused by decreased swallowing, leading to increased saliva in the mouth. Drooling usually happens while sleeping, sometimes during the day. This is typically not a dangerous side effect. Aspiration pneumonia has been reported, though is very rare. Drooling can be bothersome or make the patient appear odd. First line strategies include having the patient sleep with a towel on their pillow. During the day, chewing sugarless gum stimulates the swallowing reflex, and can be effective. Medications can be used, though they often create their own side effects. Commonly prescribed medications that dry the mouth, such as benztropine, are often not helpful and can worsen constipation or cognition. Oral glycopyrrolate is an anticholinergic that does not cross the blood brain barrier, and can sometimes be helpful. Other medications that have been helpful are ipratropium spray orally, ophthalmic atropine 1% drops sublingually, and terazosin. In severe refractory cases, botulinum toxin has been used. Peer-run support groups that directly address living with side effects can be helpful.
Below is a helpful infographic on sialorrhea, courtesy of Greti Barokas, Emory University School of Medicine.