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For men, abnormally large breasts can be distressing and embarrassing. Breast cancers account for only 1 percent of all cases of male breast enlargement.[1] The remaining cases are caused by benign conditions known as gynecomastia (proliferation in the glandular breast tissue) and pseudogynecomastia (proliferation of the fatty tissue in the breast) in men.
Gynecomastia occurs due to an imbalance in the effects of androgen hormones (such as testosterone, which inhibits glandular breast...
For men, abnormally large breasts can be distressing and embarrassing. Breast cancers account for only 1 percent of all cases of male breast enlargement.[1] The remaining cases are caused by benign conditions known as gynecomastia (proliferation in the glandular breast tissue) and pseudogynecomastia (proliferation of the fatty tissue in the breast) in men.
Gynecomastia occurs due to an imbalance in the effects of androgen hormones (such as testosterone, which inhibits glandular breast tissue) and estrogen hormones (which stimulate glandular breast tissue).[2] This imbalance can be normal (physiological gynecomastia), such as when it occurs in newborns (due to a surge of maternal hormones transferred to the baby through the placenta during delivery), adolescent boys (due to low testosterone levels) and elderly men (due to age-related decline in testosterone levels).
The hormone imbalance also can be abnormal (nonphysiologic) when it develops with certain disorders, including classic hypogonadism (see definition in the testosterone article), severe liver disease, hyperactive thyroid, chronic kidney disease, malnutrition and tumors of the testicles. It also can result from substance abuse.
Certain medications collectively account for 10 to 25 percent of gynecomastia cases.[3] Learn about these medications to avoid this troublesome adverse effect.
Drugs implicated in gynecomastia
The table below provides examples of many drugs that have been shown to cause gynecomastia. The signs of drug-related gynecomastia are like those for other types of gynecomastia:[4] Male patients report breast enlargement (usually of both breasts), which is associated with breast pain or tenderness in most patients.[5] The symptoms of drug-related gynecomastia can occur within several weeks or months after starting the causative drug.[6]
Drugs may cause gynecomastia in various ways. Some drugs increase the effect of estrogen.[7] Other drugs reduce the effect of androgens in various ways.[8] Additionally, some drugs increase the blood level of the hormone prolactin, which stimulates the production of milk and also blocks the effect of hormones released by the pituitary that promote androgen production.
No medication is approved for drug-induced gynecomastia. However, discontinuing the causative drug, if appropriate, often results in breast shrinkage.[9] But if gynecomastia has been present for over a year, it is unlikely to resolve substantially.[10]
Examples of Oral Drugs That Induce Gynecomastia[11],[12],[13],[14],[15]
| Drug Family | Drug Names† |
|---|---|
| Antibiotics and antifungal drugs |
|
| Antipsychotics |
|
| High blood pressure and heart drugs |
|
| Gastrointestinal drugs |
|
| Lung drugs |
|
| Seizure drugs |
|
| Some prostate (or baldness) drugs |
|
| Tetracyclic/tricyclic antidepressants |
|
†Note: Combination drugs were excluded from this table.
*Designated as Do Not Use
**Designated as Limited Use
What You Can Do
If you are a man with gynecomastia for no apparent reason, make a list of your drugs and review it with your doctor. He or she may ask you to stop, or lower the dose of, the causative drug.
References
[1] Niewoehner CB, Schorer AE. Gynaecomastia and breast cancer in men. BMJ. 2008;336(7646):709-713.
[2] Dickson G. Gynecomastia. Am Fam Physician. 2012;85(7):716-722.
[3] Dickson G. Gynecomastia. Am Fam Physician. 2012;85(7):716-722.
[4] Drug-induced gynaecomastia. Prescrire Int. 1994;3(11):77-78.
[5] Nuttall FQ, Warrier RS, Gannon MC. Gynecomastia and drugs: a critical evaluation of the literature. Eur J Clin Pharmacol. 2015;71(5):569-578.
[6] Drug-induced gynaecomastia. Prescrire Int. 2018;27(198):263-266.
[7] Ibid.
[8] Ibid.
[9] Dickson G. Gynecomastia. Am Fam Physician. 2012;85(7):716-722.
[10] Eckman A, Dobs A. Drug-induced gynecomastia. Expert Opin Drug Saf. 2008;7(6):691-702.
[11] Bowman JD, Kim H, Bustamante JJ. Drug-induced gynecomastia. Pharmacotherapy. 2012;32(12):1123-1140.
[12] Deepinder F, Braunstein GD. Drug-induced gynecomastia: an evidence-based review. Expert Opin Drug Saf. 2012;11(5):779-795.
[13] Drug-induced gynaecomastia. Prescrire Int. 2018;27(198):263-266.
[14] Eckman A, Dobs A. Drug-induced gynecomastia. Expert Opin Drug Saf. 2008;7(6):691-702.
[15] Goldman RD. Drug-induced gynecomastia in children and adolescents. Can Fam Physician. 2010;56(4):344-345.
