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What are the Causes of Gynaecomastia?

Gynaecomastia is a condition that can occur in men of any age. It results in the development of mammary glands and extra tissue forming around the nipples. Gynaecomastia can occur at any stage of a male’s life, although it is most commonly found in new-borns, during puberty, and in the elderly.

Photo of male with severe asymmetrical gynecomastia

Key Points

  • Gynaecomastia involves benign enlargement of breast tissue in males, often due to hormonal imbalances.
  • It can significantly affect psychological health and social interactions.
  • Understanding its pathophysiology is key to effective treatment.
  • Pharmacotherapy choices vary based on individual patient factors.

Possible Causes of Gynaecomastia

Gynaecomastia stems from an imbalance in hormonal levels, particularly the relative increase of estrogen compared to testosterone. This hormonal disturbance leads to the proliferation of glandular breast tissue in males, differentiating it from adipose tissue enlargement, a condition known as pseudogynecomastia.

While the symptoms are largely the same, the exact cause(s) can vary. Hormone imbalances, drug use (prescription or otherwise) and other conditions that affect the production of testosterone are among the many causes.


The glandular tissue proliferation central to Gynaecomastia is influenced by multiple factors. Hormonal fluctuations, particularly during puberty and aging, play a critical role. Increased estrogen activity, whether from external sources or internal metabolic changes, can lead to breast tissue development, resembling female breast growth.

Prevalence and Impact on Quality of Life

Gynaecomastia's prevalence varies widely, with notable increases observed in newborns, adolescents undergoing puberty, and men over 50. The psychological and social impact of this condition is profound. Individuals with Gynaecomastia often experience lowered self-esteem and altered body image, leading to social withdrawal and emotional distress.

  • In Infants: New-borns may have a certain amount of breast tissue due to oestrogen transference between mother and child. This may last a couple of weeks before the breast tissue reduces.
  • During Puberty: Hormone imbalances during puberty may cause some males to develop breast tissue. This is because of fluctuating hormone levels. All men produce a certain amount of oestrogen; however, their testosterone is usually high enough to prevent breasts from forming. If testosterone levels drop during puberty, breasts may become visible, though they will usually return to normal between the ages 16-18.
  • In the Elderly: As men grow older the body's production of testosterone begins to slow. With many older men not able to do strenuous exercise, body fat may begin to form, which in turn, increases oestrogen levels within the body and therefore causes breast growth.
  • Drugs (adverse effects): Some prescription drugs can cause breast growth in men. Spironolactone (Aldactone), Digoxin and Furosemide (Lasix) are among the drugs that may cause gynaecomastia. Anabolic steroid use in body building can lead to pure glandular gynaecomastia.
  • Underlying Conditions: The development of breasts in males may be due to an underlying cause such as testicular cancer, which affects the testosterone levels. It is important to check for lumps regularly, especially if you develop breast tissue. If in doubt, visit your G.P.
  • Overweight: Though not technically gynaecomastia, overweight males can gain extra fatty tissue in the breast area. Unlike gynaecomastia, this extra tissue can be burnt off by maintaining a healthy diet and getting plenty of exercise.

Overview of Pharmacotherapy in Gynaecomastia

Addressing Gynaecomastia pharmacologically necessitates a comprehensive understanding of its underlying causes and patient-specific factors. The choice of treatment is influenced by several criteria, including the patient’s age, overall health, and the specific characteristics of their condition.

General Approach to Treatment

The treatment for Gynaecomastia begins with a thorough assessment of the individual’s condition, considering factors like the duration of Gynaecomastia and its severity. The primary goals of treatment include reducing breast size and alleviating any associated pain or discomfort.

Criteria for Selecting Pharmacotherapy

When selecting pharmacotherapy, clinicians consider a range of factors. These include the patient's age, the presence of underlying medical conditions, and the stage of Gynaecomastia. The treatment modalities may include hormonal therapies such as testosterone supplements, estrogen receptor blockers, or aromatase inhibitors, each targeting specific hormonal pathways involved in Gynaecomastia development.

Tamoxifen: A Key Player in Gynaecomastia Treatment

Tamoxifen, a selective estrogen receptor modulator, has emerged as a significant treatment for Gynaecomastia. Clinical studies have highlighted its efficacy, with one retrospective study showing that 78% of patients treated with Tamoxifen experienced complete resolution, outperforming alternative treatments. This efficacy, coupled with a relatively lower side effect profile, positions Tamoxifen as a preferable choice for many.

Mechanism of Action

Tamoxifen works by blocking estrogen's influence on breast tissue. It blocks estrogen receptors, effectively reducing the glandular tissue proliferation associated with Gynaecomastia.

Effectiveness Across Age Groups

Various clinical studies reveal Tamoxifen's efficacy across different age groups. It's found to be effective in a majority of patients, showcasing its versatility as a treatment option.

Potential Side Effects

While Tamoxifen is generally well-tolerated, it's not devoid of side effects. Common ones include mood fluctuations and hot flashes. Rare but serious side effects necessitate vigilant monitoring and management.

Drugs That May Cause Gynaecomastia

Recognizing drug-induced Gynaecomastia is essential for accurate diagnosis and treatment. Certain drugs, particularly anti-androgens and anabolic steroids, are known to disrupt hormonal balance, leading to Gynaecomastia.

By Known or Proposed Mechanisms

The list of drugs includes those that either increase estrogen or decrease testosterone levels, leading to the development of Gynaecomastia. Understanding these mechanisms aids in both prevention and targeted treatment.

By Uncertain Mechanisms

There is ongoing research into other drugs suspected of causing Gynaecomastia, where the mechanisms remain unclear. This area of study is crucial for comprehensive management strategies.

Glossary: Understanding Medical Terms

  1. Gynaecomastia: The development of enlarged breast tissue in males, usually due to hormonal imbalances.
  2. Mammary Glands: Glandular tissue in the breast that produces milk in females, present in a rudimentary form in males.
  3. Hormonal Imbalances: A condition where there is an uneven level of hormones in the body, often estrogen and testosterone in this context.
  4. Pseudogynecomastia: Enlargement of male breast tissue due to excess fatty tissue, not glandular tissue.
  5. Oestrogen: A hormone that promotes female secondary sexual characteristics, present in both genders but at higher levels in females.
  6. Testosterone: The primary male sex hormone responsible for male sexual characteristics.
  7. Tamoxifen: A medication that blocks estrogen receptors, used in treating Gynaecomastia.
  8. Selective Estrogen Receptor Modulator (SERM): A type of drug that acts on estrogen receptors in a selective manner, like Tamoxifen.
  9. Diuretics: Medications designed to increase the amount of water and salt expelled from the body as urine.
  10. Anabolic Steroids: Synthetic substances similar to the male sex hormone testosterone, often used for muscle growth.
  11. Aromatase Inhibitors: Drugs that reduce estrogen levels by inhibiting the enzyme aromatase, which converts androgens to estrogens.


Gynaecomastia, while primarily a benign condition, can significantly affect quality of life. Pharmacological intervention, especially through agents like Tamoxifen, plays a vital role in management. Ongoing research and deeper understanding of the condition's etiology are essential for optimizing treatment and patient outcomes.

Medical References

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⚠️ Disclaimer: The information provided in this article is for educational purposes only and should not be considered as medical advice. Please consult a healthcare professional for personalized advice.