Do marijuana and alcohol use cause gynecomastia in males?

Marijuana and Alcohol Use and Gynecomastia

Both marijuana and alcohol can cause gynecomastia, though the evidence quality differs substantially between the two substances—alcohol has well-established mechanisms through liver disease and direct hormonal effects, while marijuana's association is noted in guidelines but lacks robust mechanistic data.

Alcohol and Gynecomastia

Alcohol is definitively associated with gynecomastia through multiple pathophysiologic mechanisms. 1

Mechanisms of Alcohol-Induced Gynecomastia

• Alcohol causes feminization in up to 80% of chronic alcoholic men, manifesting as gynecomastia, testicular atrophy, impotence, and altered body hair patterns. 2

• The pathogenesis operates through two distinct pathways:

  • Indirect effects via alcohol-induced liver disease: Hepatic dysfunction permits peripheral escape of steroid precursors that convert to estrogenic substances, which the damaged liver cannot adequately clear 2
  • Direct endocrine effects: Alcohol directly impairs testicular steroidogenesis and testosterone production, while simultaneously diminishing hypothalamic-pituitary function 2

• Alcohol is classified as "probably associated" with gynecomastia based on systematic evidence review. 1

Clinical Implications

• The estrogen/androgen ratio imbalance from both liver dysfunction and direct testicular suppression creates the hormonal milieu for breast tissue proliferation. 3

• Chronic alcohol use should be specifically assessed when evaluating any male patient presenting with gynecomastia, as it represents a modifiable risk factor. 1, 2

Marijuana and Gynecomastia

Cannabis use is recognized as a potential cause of gynecomastia, particularly with chronic use initiated at young ages, though the evidence base is less robust than for alcohol.

Evidence for Cannabis-Induced Gynecomastia

• The Annals of Internal Medicine guidelines note that chronic cannabis use, especially when started at a young age, may have significant effects on hormonal systems. 4

• Adolescents who use marijuana should be alerted that gynecomastia might develop as a consequence. 5

• The mechanism likely involves disruption of the testosterone-estrogen balance, though specific pathophysiologic pathways remain less well-characterized than alcohol. 5

Evidence Quality Considerations

• Most drug-gynecomastia associations, including marijuana, are based on case reports and case series rather than controlled studies. 1

• The 2024 ASCO cannabis guidelines extensively review cannabis-related adverse effects but do not specifically list gynecomastia among documented complications, suggesting the association may be less consistent than other cannabis-related effects. 6

Clinical Evaluation Algorithm

Step 1: Obtain Detailed Substance Use History

• Specifically quantify alcohol consumption patterns (frequency, quantity, duration) and assess for signs of chronic liver disease. 2

• Document marijuana use including age of initiation, frequency, duration, and cumulative exposure. 4, 5

• Evaluate temporal relationship between substance use initiation and gynecomastia onset. 7

Step 2: Physical Examination

• Assess for stigmata of chronic liver disease (spider angiomata, palmar erythema, ascites) in alcohol users. 2

• Perform complete testicular examination to assess size, consistency, and presence of atrophy. 8

• Differentiate true gynecomastia (glandular tissue directly under nipple, soft/rubbery/firm) from pseudogynecomastia (fatty tissue deposition). 8

Step 3: Laboratory Assessment

• Measure serum estradiol in all patients with gynecomastia, particularly before considering any hormonal interventions. 8

• Obtain morning total testosterone, LH, and FSH to characterize the hormonal profile. 8

• Assess liver function tests in alcohol users to evaluate for hepatic dysfunction contributing to hormonal imbalance. 2

• If testosterone is low with low/normal LH, measure prolactin to exclude hyperprolactinemia. 8

Step 4: Management Based on Findings

• Discontinue or reduce the offending substance (alcohol or marijuana) as primary intervention. 5

• For alcohol-related cases with liver disease, address underlying hepatic dysfunction and consider hepatology referral. 2

• Refer patients with elevated baseline estradiol to endocrinology for comprehensive hormonal evaluation. 8

• Observe for spontaneous resolution, which occurs in up to 50% of cases with noncyclical breast symptoms. 8

Important Caveats

• Drug-induced gynecomastia often presents as an "acute gynecomastia syndrome" characterized by unilateral painful/tender breast with enlargement that may resolve spontaneously over time, making causality difficult to establish definitively in individual patients. 9

• The absence of abnormal hormonal profiles in many reported cases suggests mechanisms beyond simple estrogen/androgen imbalance may be operative. 9

• Gynecomastia increases with age independent of substance use, complicating attribution in older patients with long-standing alcohol or marijuana use. 9

• Surgical intervention is very rarely required; most cases resolve with substance discontinuation alone. 5