Can marijuana and other drug use cause gynecomastia?

Marijuana and Other Drug Use as Causes of Gynecomastia

Marijuana and several other drugs can cause gynecomastia through hormonal imbalances that lead to increased estrogen action or decreased androgen effects on breast tissue. While physiologic gynecomastia is common in newborns, adolescents, and older men, drug-induced gynecomastia represents approximately 10-25% of all cases 1.

Marijuana and Gynecomastia

• Marijuana (cannabis) use has been associated with gynecomastia development in adolescents and adults 2
• The mechanism likely involves disruption of the normal hormonal balance, though specific pathways are not fully elucidated in current guidelines 3, 4
• Chronic cannabis use, especially when started at a young age, may have more significant effects on hormonal systems 5

Other Drugs Commonly Associated with Gynecomastia

Medications with Strong Evidence of Causation

• Hormonal agents:

  • Estrogens and medications with estrogenic activity directly stimulate breast tissue growth 4
  • Testosterone and anabolic steroids can cause gynecomastia through conversion to estrogens 4
  • Androgen receptor blockers (cyproterone acetate, spironolactone) 4
  • 5-alpha reductase inhibitors (finasteride, dutasteride) 4
  • GnRH agonists/antagonists used in prostate cancer treatment 4

• Non-hormonal medications:

  • Spironolactone (significantly higher risk than eplerenone) 4
  • Ketoconazole (can cause hypogonadism leading to gynecomastia) 4
  • Cimetidine 1
  • Digoxin (though evidence is contradictory) 4, 6

Illicit Substances Associated with Gynecomastia

• Marijuana 2
• Alcohol 2
• Heroin 2
• Amphetamines 2
• Anabolic steroids 2, 1

Pathophysiology of Drug-Induced Gynecomastia

Gynecomastia results from an imbalance between estrogenic and androgenic effects on breast tissue, leading to:

• Increased estrogen production or action 7
• Decreased androgen production or action 7
• Direct stimulation of breast tissue growth 4
• Hyperprolactinemia (caused by certain medications) 4

Diagnostic Approach for Suspected Drug-Induced Gynecomastia

• Differentiate true gynecomastia (glandular tissue proliferation) from pseudogynecomastia (fatty tissue deposition), especially in patients with elevated BMI 3
• Gynecomastia typically presents as a soft, rubbery, or firm mobile mass directly under the nipple and is often painful, especially when present for less than 6 months 3
• Gynecomastia is bilateral in approximately 50% of patients 3
• Perform a complete medication and substance use history, including prescription medications, over-the-counter drugs, supplements, and illicit substances 3, 7

Management of Drug-Induced Gynecomastia

• First-line approach: Discontinuation of the offending drug or substance (including marijuana) is the mainstay of treatment 2, 7
• Most cases resolve within several months after removing the causative agent 8
• For persistent, painful gynecomastia:
  • Estrogen receptor modulators may be considered for patients with hormonal imbalances 3
  • Surgical intervention is rarely required but may be considered for persistent cases causing significant psychological distress 2

Special Considerations

• Patients with elevated baseline estradiol measurements should be referred to an endocrinologist to determine the underlying hormonal cause 3
• Men with gynecomastia who are interested in fertility should have a reproductive health evaluation performed prior to treatment 3
• Serum estradiol should be measured in testosterone-deficient patients who present with breast symptoms or gynecomastia prior to starting testosterone therapy 3

Common Pitfalls to Avoid

• Failing to obtain a complete drug history, including recreational substances like marijuana 8, 2
• Unnecessary imaging in clear cases of gynecomastia can lead to additional unnecessary benign biopsies 3
• Overlooking drug interactions that may potentiate gynecomastia (e.g., digoxin and furosemide) 6
• Neglecting to consider underlying conditions that may contribute to gynecomastia in addition to drug use 7