What is the role of drugs in the etiology of gynecomastia?

Updated: Mar 22, 2018
  • Author: George Ansstas, MD; Chief Editor: George T Griffing, MD  more...
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Various drugs are implicated in gynecomastia and can be classified into categories (although drugs in the same class do not all cause gynecomastia to the same extent). [17, 18, 19]

Of note, the pathophysiologic mechanism for some drugs, such as estrogens or antiandrogens, is quite clear. However, for others such as spironolactone, the mechanism is more complex. Spironolactone can increase the aromatization of testosterone to estradiol, decrease testosterone production by the testes, increasing the rate of testosterone clearance by displacing it from SHBG, and also binding to androgen receptors leading to gynecomastia through estrogen/testosterone imbalance. Another example is tea tree oil, which possesses weak estrogenic and antiandrogenic activities that may contribute to an imbalance in estrogen and androgen pathway signaling. Estrogenic or antiandrogenic activities have been reported for other essential oils and some of their monoterpene constituents. [20]

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