A successful treatment strategy for clozapine-induced parotid swelling: a clinical case and systematic review

Parotid gland swelling is a less frequently reported side effect of clozapine and has no licensed treatment. A 58-year-old man treated with clozapine for treatment-resistant schizophrenia developed bilateral painful parotid swellings and hypersalivation. Initial trials of dose alteration and antihypersalivatory medication had limited success. A combination of benzatropine and terazosin was successful in treating the parotid hyperplasia. Clozapine was the probable cause of parotid swelling in our case, as established using the Naranjo adverse drug reaction probability scale and World Health Organization causality categories. Literature for treatments of clozapine-induced parotid gland swellings was reviewed. None of the published articles suggested a treatment regimen for clozapine-induced parotid hyperplasia. Most reports only highlighted the occurrence of salivary gland swelling with clozapine. Others mentioned management strategies, which included spontaneous resolution, or resolution on discontinuing clozapine. One report, a trial with benzatropine and ipratropium, had variable success. In this case the re-emergence of parotid swelling when terazosin and benzatropine doses were missed followed by a quick resolution upon recompliance, goes some way in proving that this combination is indeed effective. The combination of terazosin and benzatropine appears to have a role in treating parotid gland swellings induced by clozapine.