Not a cause of gynecomastia :

Gynecomastia refers to enlargement of the male breast. It is caused by excess estrogen action and is usually the result of an increased estrogen/androgen ratio. Drugs can cause gynecomastia by acting directly as estrogenic substances (e.g., oral contraceptives,isoniazid (INH),phytoestrogens, digitalis), inhibiting androgen synthesis (e.g., ketoconazole), or action (e.g., spironolactone). Ref :Bhasin S., Jameson J.L. (2012). Chapter 346. Disorders of the Testes and Male Reproductive System. In D.L. Longo, A.S. Fauci, D.L. Kasper, S.L. Hauser, J.L. Jameson, J. Loscalzo (Eds), Harrison's Principles of Internal Medicine, 18e.