Key Points

• Gynaecomastia is a benign proliferation of male breast tissue due to an imbalance between oestrogenic activity (which stimulates breast tissue) and androgenic activity (which inhibits this tissue). This imbalance can be related to physiological causes, various disorders, or toxic substances including some cosmetics, anabolic steroids and various medicines.
   
• Drug-induced gynaecomastia appears several weeks or months after starting the drug. In general, it disappears after the drug is discontinued. 
   
• The drugs which can cause gynaecomastia are mainly those with oestrogenic, antiandrogenic or hyperprolactinaemia-inducing effects, including: treatments for prostatic hypertrophy or cancer; neuroleptics; potassium-sparing diuretics with anti-aldosteronergic effects, such as spironolactone; cimetidine; some cancer drugs; ketoconazole; and isoniazid.
   
• When a patient complains of gynaecomastia, it is worthwhile reviewing with him the list of drugs he is taking or has recently taken, not forgetting products which are not classified as medicines. Their role should be considered among the range of potential causes.
   

©Prescrire 1 November 2018

"Drug-induced gynaecomastia" Prescrire Int 2018; 27 (198): 263-266. (Pdf, subscribers only)

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