Some medications increase the risk for gynecomastia--the enlargement of breast tissue in males. This can be an embarrassing side effect, engendering annoying comments from others on the beach, in the gym and elsewhere. According to medical professor Bernard M. Karnath at the University of Texas in his 2008 article on gynecomastia, up to 10 percent of gynecomastia cases are caused by medications, such as spironolactone and hormonal therapy to treat prostate cancer. Drugs of abuse, such as anabolic steroids and marijuana, can also cause gynecomastia.
Androgen receptor antagonists
Dr. Karnath says that some drugs that act as androgen receptor antagonists, affecting male hormone levels and leading to the development of gynecomastia. Spironolactone and cimetidine are two drugs that are androgen receptor antagonists and are known to cause gynecomastia in some cases. Spironolactone may block the synthesis of testosterone in addition to acting as an androgen receptor agonist, thus increasing the risk for gynecomastia in two ways.
Marijuana is also an androgen receptor antagonist and thus can cause gynecomastia.
Highly Active Antriretroviral Therapy (HAART)
Medications used to treat males with the human immundeficiency virus--HIV--may cause gynecomastia, says Karnath, who notes that in one study of more than 1,300 men being treated with highly active antiretroviral therapy--HAART--about 2 percent developed gynecomastia. However, in about 75 percent of the cases, the gynecomastia resolved within about 9 months. It is unknown how HAART causes gynecomastia in those who develop this side effect.
Psychiatric Drugs
According to Ruth E. Johnson, M.D. and M. Hassan Murad, M.D. in their 2009 article for "Mayo Clinic Proceedings," some psychiatric medications may lead to the development of gynecomastia, especially diazepam, an anti-anxiety drug, as well as drugs that are tricyclic antidepressants, antipsychotic medications such as haloperidol and drugs in the category of atypical antipsychotics. How these drugs may cause gynecomastia is unclear.
Anabolic Steroids
The abuse of anabolic steroids, drugs used to increase muscle mass when abused, may lead to the development of gynecomastia, according to Ran D. Golman, M.D. in his article on drug-induced gynecomastia in children and adolescents for "Canadian Family Physician" in 2010. Anabolic steroids affect male hormones, and these drugs may shrink male testicles and cause other serious side effects in addition to gynecomastia among male abusers. Golman notes that drug-induced gynecomastia is more common in adults than in children or adolescents.
Therapy for Prostate Cancer
Men with prostate cancer may be treated with antiandrogen therapy, according to University of Washington urology professor Paul H. Lange, M.D. in "Prostate Cancer for Dummies." These drugs are used to block the action of testosterone, because testosterone makes prostate cancer grow. Hormonal antiandrogen therapy may also cause impotence, hot flashes and irritability. Some forms of hormonal therapy for men with prostate cancer are luteinizing hormone-releasing homrmones, such as goserelin, buserelin and leuporolide, nonsteroidal antiandrogens such as bicalutamine and flutamide and steroidal antiandrogens such as cyproterone.
Antibiotics
Some antibiotics may lead to the development of gynecomastia, according to Dr. Johnson and Dr. Murad, M.D. The antibiotics most likely to cause gynecomastia include drugs such as metronidazole, isoniazid and ketoconazole, say Johnson and Murad. Drugs such as metronidazole and keotconazole may inhibit testosterone while isoniazid directly causes gynecomastia.
References
- "Prostate Cancer for Dummies"; Paul H. Lange, M.D. and Christine Adamec; 2003
- "Hospital Physician"; Gynecomastia: Bernard M. Karnath, M.D.; July 2008
- "Canadian Family Physician"; Drug-induced Gynecomastia in Children and Adolescents; April 2010
- "Mayo Clinic Proceedings"; Gynecomastia: Pathophysiology, Evaluaton, and Management; Ruth E. Johnson, M.D. and M. Hassan Murad, M.D., MPH; November 2009
