Gynaecomastia — the benign enlargement of glandular breast tissue in males — is more common than many people realise, affecting males at various life stages from newborns to older adults. Driven by an imbalance between oestrogen and androgen activity, it can arise from natural hormonal shifts, underlying medical conditions, or certain medicines. Whilst usually benign, the condition can cause significant physical discomfort and psychological distress. This article explains what gynaecomastia is, what causes it, how it is treated, which medicines and conditions are linked to it, and when to seek medical advice.

What Is Gynaecomastia and What Causes It?

Gynaecomastia is benign glandular breast tissue enlargement in males caused by an oestrogen–androgen imbalance, occurring physiologically at birth, puberty, and older adulthood, or due to medical conditions, medicines, or tumours.

Gynaecomastia refers to the benign enlargement of glandular breast tissue in males. It is distinct from pseudogynaecomastia, which involves fatty tissue accumulation without true glandular growth. The condition can affect one or both breasts and may present with tenderness, firmness, or a palpable disc of tissue beneath the nipple.

Prevalence varies considerably by age group and the diagnostic criteria used; NICE CKS and NHS sources note that gynaecomastia is common, particularly during puberty and older adulthood, affecting a substantial proportion of males at some point in their lives.

The underlying cause is typically an imbalance between oestrogen and androgen activity in breast tissue. Oestrogens stimulate glandular growth, whilst androgens — primarily testosterone — counteract this effect. When this balance is disrupted, breast tissue may proliferate. This hormonal shift can occur naturally at several life stages:

• Neonatal period: Maternal oestrogens crossing the placenta can cause transient breast enlargement in newborns, which is usually self-limiting and resolves within the first few weeks of life.

• Puberty: Hormonal fluctuations during adolescence are the most common cause in younger males, typically resolving spontaneously within one to two years.

• Older adulthood: Declining testosterone levels combined with increased body fat (which converts androgens to oestrogens via aromatisation) can trigger onset in men over 50.

Beyond physiological causes, gynaecomastia may result from underlying medical conditions, medications, or lifestyle factors. Obesity, liver disease, renal failure, hyperthyroidism, and hypogonadism are all recognised contributors. Klinefelter syndrome — a chromosomal condition affecting males — is also associated with an increased risk. In a small number of cases, oestrogen-secreting or human chorionic gonadotrophin (hCG)-secreting tumours — including testicular germ cell tumours and, rarely, adrenal tumours — may be responsible, making thorough clinical evaluation essential.

Understanding the root cause is the first step towards appropriate management. Further information is available from NICE CKS: Gynaecomastia and the NHS: Gynaecomastia pages.

Treatment Options Available for Gynaecomastia

Treatment depends on cause and duration; watchful waiting is first-line for pubertal cases, whilst tamoxifen (off-label) or surgery may be considered for persistent or distressing gynaecomastia.

The appropriate treatment for gynaecomastia depends largely on its underlying cause, duration, and the degree of physical or psychological impact on the individual. In many cases — particularly in adolescents experiencing pubertal gynaecomastia — watchful waiting is the recommended first-line approach, as the condition frequently resolves spontaneously within 12 to 24 months without any intervention.

Where an identifiable cause is found, addressing it directly often leads to improvement. For example, discontinuing or substituting a causative medication, treating an underlying hormonal disorder, or achieving weight loss in cases linked to obesity may all result in regression of breast tissue. Any medication changes must be made only under medical supervision.

For persistent or significant gynaecomastia, the following options may be considered:

• Pharmacological treatment: Tamoxifen (a selective oestrogen receptor modulator) has modest evidence of benefit for recent-onset, tender gynaecomastia, particularly when used within the first six to twelve months of onset, before fibrotic changes develop. Anastrozole (an aromatase inhibitor) has shown limited benefit in clinical studies and is not routinely recommended. Both medicines are used off-label for this indication in the UK — neither holds a UK marketing authorisation specifically for gynaecomastia — and their use should be guided by a specialist. Prescribers should follow GMC and MHRA guidance on off-label prescribing, ensuring patients are fully informed of the potential risks, benefits, and the absence of a licensed indication. Once long-standing fibrosis has occurred (typically after 12 months or more), pharmacological treatment is unlikely to be effective. Refer to the BNF and the electronic Medicines Compendium (eMC) SmPCs for tamoxifen and anastrozole for full prescribing information.

• Surgical intervention: Surgical reduction — either via liposuction, glandular excision, or a combination — is considered for cases that are longstanding, causing significant discomfort, or where psychological distress is substantial. In the UK, NHS funding for surgery is subject to local Integrated Care Board (ICB) commissioning policies and exceptional funding criteria; availability therefore varies by area and is not guaranteed. Surgery is more commonly performed in the independent sector. The British Association of Plastic, Reconstructive and Aesthetic Surgeons (BAPRAS) provides guidance on surgical options and what patients can expect.

A referral to an endocrinologist or breast surgeon may be appropriate depending on clinical findings. NICE guidance supports a patient-centred approach, ensuring that treatment decisions are made collaboratively and that psychological wellbeing is considered alongside physical symptoms.

If you believe a medicine may have caused or worsened gynaecomastia, this can be reported to the MHRA via the Yellow Card Scheme at yellowcard.mhra.gov.uk.

Medicines and Conditions Linked to Gynaecomastia

Anabolic steroids, spironolactone, anti-androgens, antipsychotics, and antiretrovirals are among the medicines most strongly linked to gynaecomastia; underlying conditions include hypogonadism, liver disease, and Klinefelter syndrome.

A wide range of medicines and medical conditions are recognised as contributing factors in gynaecomastia. Identifying these associations is clinically important, as addressing the underlying cause can sometimes lead to resolution without further intervention. A structured medication review — including prescribed medicines, over-the-counter products, and supplements — is an essential part of clinical assessment.

Medicines with well-established associations include:

• Anabolic steroids and exogenous androgens: Paradoxically, exogenous androgens can be converted to oestrogens via aromatisation, stimulating breast tissue growth.

• Anti-androgens and hormonal agents: Spironolactone, cyproterone acetate, bicalutamide, finasteride, dutasteride, and GnRH analogues (used in prostate cancer and other conditions) reduce androgen activity and are well-recognised causes.

• Oestrogens and hCG: Direct oestrogen exposure or hCG administration can stimulate breast tissue.

• Antipsychotics: Risperidone and amisulpride have strong evidence for causing hyperprolactinaemia, which can contribute to gynaecomastia. Other antipsychotics may also be implicated.

• Cardiovascular medicines: Digoxin has a well-established association. Spironolactone (also used in heart failure) is particularly notable.

• Antiretrovirals: Efavirenz and some other antiretroviral agents have been linked to gynaecomastia.

• Other medicines: Cimetidine (an H2-receptor antagonist), ketoconazole, isoniazid, and certain alkylating chemotherapy agents are also recognised causes.

Medicines with weaker or less consistent evidence — including some proton pump inhibitors, calcium channel blockers such as amlodipine, ACE inhibitors, some tricyclic antidepressants, and cannabis — have been reported in association with gynaecomastia in some cases, but the evidence base is limited and inconsistent. These associations should be interpreted with caution. Refer to individual BNF entries and eMC SmPCs for the most current prescribing information.

If you suspect a medicine is causing or worsening gynaecomastia, please report this to the MHRA via the Yellow Card Scheme at yellowcard.mhra.gov.uk.

Underlying medical conditions that may cause or worsen gynaecomastia include hypogonadism, hyperprolactinaemia, hyperthyroidism, chronic liver disease (which impairs oestrogen metabolism), chronic kidney disease, Klinefelter syndrome, and adrenal or testicular tumours (including hCG-secreting germ cell tumours).

In many cases, no single definitive cause is identified; this is referred to as idiopathic gynaecomastia. Nonetheless, a thorough medication review and clinical assessment remain essential components of evaluation. Further detail is available from NICE CKS: Gynaecomastia and the NHS: Gynaecomastia pages.

When to Seek Medical Advice About Breast Tissue Changes

Seek prompt GP assessment for any hard, irregular, or rapidly growing breast lump, nipple discharge, skin changes, or associated testicular symptoms, as these may indicate serious pathology including male breast cancer.

Whilst gynaecomastia is most often benign, any new or changing breast tissue in males should be assessed by a healthcare professional. Prompt evaluation helps to exclude rare but serious causes, including male breast cancer, which — although uncommon — accounts for approximately 1% of all breast cancer diagnoses in the UK according to NHS data.

Seek medical advice promptly if you notice any of the following:

• A hard, irregular, or rapidly growing lump in the breast

• A lump that is not centrally located beneath the nipple (gynaecomastia typically presents as a symmetrical, rubbery disc of tissue directly behind the nipple)

• Nipple discharge, particularly if bloodstained

• Skin changes over the breast, such as dimpling, puckering, or redness

• Swelling of the lymph nodes in the armpit

• Unexplained weight loss, fatigue, or other systemic symptoms

• Breast changes accompanied by testicular pain, swelling, or a palpable mass

Your GP will typically begin with a thorough history and physical examination, followed by blood tests. Standard investigations include early-morning (approximately 9 am) total testosterone (with repeat confirmation if low), oestradiol, LH, FSH, prolactin, and thyroid function tests. Liver and renal function tests are also usually requested. Where a tumour is suspected — particularly in the presence of testicular symptoms or signs — beta-hCG (a tumour marker) should be measured, and testicular ultrasound considered. Depending on findings, referral to an endocrinologist, urologist, or breast clinic may follow.

In the UK, the NHS two-week wait pathway — defined by NICE NG12 (Suspected cancer: recognition and referral) — ensures that patients with features suggestive of cancer are seen by a specialist promptly. Your GP can refer you via this pathway if clinically indicated.

Even in the absence of alarming features, persistent gynaecomastia lasting more than six months, or that which is causing significant psychological distress, warrants a GP consultation. Early assessment provides reassurance and opens the door to appropriate management. Further information is available from NHS: Breast cancer in men and NICE NG12.

Living With Gynaecomastia: Support and Next Steps

Gynaecomastia carries a significant psychological burden; open GP communication, NHS Talking Therapies, lifestyle measures, and specialist referral can all support men in managing the condition effectively.

For many men and adolescents, gynaecomastia carries a significant psychological burden that extends well beyond the physical changes. Feelings of embarrassment, self-consciousness, and reduced confidence are commonly reported, and in some cases the condition can contribute to social withdrawal, anxiety, or depression. Acknowledging this emotional dimension is an important part of holistic care.

Open communication with a GP or specialist is the most important first step. Many men delay seeking help due to embarrassment, but healthcare professionals are well-equipped to discuss breast changes sensitively and without judgement. If psychological distress is significant, a referral to a counsellor or psychologist may be beneficial alongside any physical treatment. NHS Talking Therapies (previously known as IAPT) offers free, confidential psychological support for adults in England; your GP can refer you, or you can self-refer in many areas.

Practical steps that may help whilst awaiting assessment or treatment include:

• Wearing well-fitted, supportive clothing; discreet compression vests or garments may help reduce self-consciousness whilst awaiting assessment or treatment

• Maintaining a healthy weight through a balanced diet and regular exercise, which may help reduce oestrogen levels associated with excess adipose tissue

• Avoiding known contributing substances such as cannabis and excessive alcohol

• Reviewing any non-essential supplements — particularly those marketed for bodybuilding — with a pharmacist or GP, as some contain compounds that may exacerbate the condition

Support groups and online communities can also provide a valuable sense of solidarity for those affected. The British Association of Plastic, Reconstructive and Aesthetic Surgeons (BAPRAS) offers guidance on surgical options for those considering intervention.

Ultimately, gynaecomastia is a manageable condition, and the majority of those affected can achieve a satisfactory outcome with appropriate support. Whether the path forward involves watchful waiting, medical treatment, or surgery, informed decision-making — guided by a trusted healthcare professional — remains the cornerstone of good care.

Useful UK resources: NICE CKS: Gynaecomastia; NHS: Gynaecomastia; NHS Talking Therapies; BAPRAS; MHRA Yellow Card Scheme (yellowcard.mhra.gov.uk).

Frequently Asked Questions