Gynaecomastia associated with proton pump inhibitors: a case series from the Spanish Pharmacovigilance System

Proton pump inhibitors (PPIs) are widely used in the management of peptic ulcer and related symptoms. They have been linked to certain endocrine adverse reactions, including gynaecomastia. The aim of the present study is to investigate the association between the use of PPIs and the development of gynaecomastia.

Reports of cases of gynaecomastia that had putatively been induced by PPIs and that had been collected by the Spanish Pharmacovigilance System via the 'yellow card' scheme, were analysed. Reporting odds ratios (RORs) were calculated as a measure of disproportionality.

Twenty-four cases of gynaecomastia associated with PPIs were identified in the database of the Spanish Pharmacovigilance System. Overall, there was a clear temporal sequence of events in all cases and the adverse effect disappeared after drug withdrawal in most of the cases; 14 patients were also receiving other drugs at the time of the adverse effect. The ROR for omeprazole exposure versus no exposure, but not that for other PPIs, showed a statistically significant elevation (ROR adjusted for age 5.23; 95% CI 3.32, 8.26).

Considering the widespread use of PPIs, gynaecomastia may affect a large number of patients. In most cases, the condition seems to be reversible with drug withdrawal. Doctors should be aware of this potential adverse reaction when prescribing PPIs to their patients over long periods of time.