Why Do I Have Man Boobs? Causes and Treatments

Man boobs, or gynaecomastia, are a common concern affecting men at various life stages, yet many feel uncertain about why they develop or what to do next. Understanding why you have man boobs starts with recognising that the condition usually stems from a hormonal imbalance between oestrogen and testosterone, though excess body fat, medications, and underlying health conditions can all play a role. This article explains the main causes, when to seek medical advice, what treatments are available on the NHS, and which lifestyle changes may help.

What causes man boobs and why do some men develop them?

Man boobs develop when oestrogen rises relative to testosterone, stimulating glandular breast tissue growth; this imbalance is most common during puberty, older age, and in men with excess body weight.

Man boobs, medically known as gynaecomastia, are caused by an imbalance between the hormones oestrogen and testosterone in the male body, leading to the growth of glandular breast tissue. All men naturally produce small amounts of oestrogen, but when this rises relative to testosterone, breast tissue can enlarge. This is distinct from pseudogynaecomastia, which refers to fat accumulation over the chest without true glandular growth.^[1][11] The two conditions can occur together, and clinical examination or imaging can help differentiate them.

Gynaecomastia is more common than many men realise. It frequently occurs during specific life stages when hormone levels fluctuate naturally:

• Newborns: Maternal oestrogen passed through the placenta can cause temporary breast swelling.

• Puberty: Hormonal shifts during adolescence are a common cause of gynaecomastia in teenage boys, according to the NHS. In many cases the condition resolves spontaneously once hormone levels stabilise, though some cases persist beyond adolescence.

• Older age: Testosterone levels decline gradually from middle age onwards, and body fat increases, both of which can tip the hormonal balance towards oestrogen.

In many cases, no single identifiable cause is found, and the condition is described as idiopathic. Excess body weight can also contribute, because fatty tissue converts androgens into oestrogen through a process called aromatisation, which can worsen or trigger breast tissue growth.^[14][15] Understanding whether the swelling is glandular or fatty is an important first step, as it influences which management options are most appropriate.

Could a medical condition or medication be behind your symptoms?

Conditions such as hypogonadism, hyperthyroidism, and liver disease, as well as medications including spironolactone, finasteride, and anabolic steroids, can cause gynaecomastia by disrupting the oestrogen-to-testosterone ratio.

Several underlying medical conditions and commonly prescribed medications can directly cause gynaecomastia by disrupting the hormonal balance between oestrogen and testosterone. Identifying a reversible cause is clinically important, because treating the root problem often leads to improvement without the need for further intervention.

Medical conditions associated with gynaecomastia include:

• Hypogonadism: Conditions such as Klinefelter syndrome or pituitary disorders that reduce testosterone production.

• Hyperthyroidism: An overactive thyroid gland raises sex hormone-binding globulin (SHBG), which reduces free testosterone and alters the oestrogen-to-androgen ratio.

• Liver disease: The liver metabolises oestrogen, so cirrhosis or chronic liver disease can lead to oestrogen accumulation.

• Kidney failure: Hormonal disruption is common in men receiving dialysis.

• Testicular tumours: Some tumours secrete hormones that shift the oestrogen-to-testosterone ratio.

A wide range of medications can also trigger breast tissue growth. Well-established examples include:

• Anti-androgens used in prostate cancer treatment (for example, bicalutamide)

• 5-alpha-reductase inhibitors such as finasteride and dutasteride

• Spironolactone, a diuretic with anti-androgenic properties

• Cimetidine (an H2 blocker)

• Certain antipsychotics, including risperidone, and some antidepressants

• Antifungals such as ketoconazole

• Antiretrovirals such as efavirenz

• Cardiac medicines including digoxin

• Anabolic steroids, which are converted to oestrogen in the body

• Exogenous oestrogens or testosterone (including testosterone replacement therapy, which can raise oestrogen through aromatisation)^[10]

• Alcohol, which can affect hormone metabolism and contribute to weight gain

• Cannabis, though the evidence for this association is limited and not conclusive

If you have recently started a new medicine and noticed breast swelling or tenderness, it is worth discussing this with your GP before stopping any prescribed treatment. Never discontinue a prescribed medication without medical advice, as the risks of doing so may outweigh the side effect. If drug-induced gynaecomastia is suspected, a prescriber may be able to switch you to an alternative therapy.

If you believe a medicine is causing a side effect, you can report this to the MHRA via the Yellow Card scheme at yellowcard.mhra.gov.uk, in addition to speaking with your prescriber or pharmacist.

When should you see a GP about chest swelling or tenderness?

See a GP promptly if breast swelling is one-sided, hard, rapidly growing, or accompanied by nipple discharge or skin changes, as these features require assessment to exclude male breast cancer.

You should see a GP if you notice new, persistent, or one-sided breast swelling, a firm lump beneath the nipple, nipple discharge, or breast pain that does not resolve within a few weeks. While gynaecomastia is usually benign, these symptoms warrant clinical assessment to rule out rarer causes, including male breast cancer. According to Cancer Research UK, breast cancer in men accounts for around 1% of all breast cancer diagnoses in the UK.

Features that make a GP appointment more urgent include:

• A hard, irregular, or rapidly growing lump

• Swelling confined to one breast only

• Nipple discharge, particularly if bloodstained

• Skin changes such as dimpling, puckering, or redness

• Swollen lymph nodes under the arm

Where any of these suspicious or unexplained features are present, your GP should refer you on an urgent suspected cancer pathway (the 2-week wait referral, as set out in NICE guideline NG12), with further imaging arranged in secondary care.

For symptoms that are clearly bilateral, soft, and associated with puberty or a known medication, a routine GP appointment is appropriate. Your GP will take a full medical history, review your current medications, and examine the chest. They may arrange initial blood tests, which typically include morning total testosterone, LH and FSH, oestradiol, prolactin, hCG, liver function, kidney function, and thyroid function.^[6] If there is any concern about a testicular cause, examination of the testes and a testicular ultrasound may also be arranged.

If you experience sudden severe chest pain, difficulty breathing, or any symptom suggesting a cardiac cause, call 999 immediately, as these are unrelated to gynaecomastia and require emergency assessment. For non-emergency concerns that arise outside of GP hours, NHS 111 can provide guidance on the most appropriate next step.

What treatments are available on the NHS for gynaecomastia?

NHS treatment ranges from watchful waiting and addressing reversible causes to off-label medication or surgery, though surgical access is subject to local ICB commissioning criteria.

NHS treatment for gynaecomastia depends on the underlying cause, the severity of symptoms, and how long the condition has been present. In many cases, particularly in adolescents, watchful waiting is the first approach, as the condition often resolves spontaneously once hormone levels stabilise.

Where a reversible cause is identified, such as a medication or an underlying condition, addressing that cause is the primary treatment. If symptoms persist despite this, or if the condition is causing significant physical discomfort or psychological distress, further options may be considered:

• Medication: There is currently no medicine licensed specifically for gynaecomastia in the UK. In some specialist settings, drugs such as tamoxifen (an anti-oestrogen) or raloxifene may be used off-label, typically in cases of recent-onset or painful gynaecomastia where the tissue is still responsive. Long-standing glandular tissue is unlikely to regress with medical treatment. NICE does not currently recommend a specific pharmacological pathway for gynaecomastia, and prescribing decisions are made on an individual basis by a specialist.^[5]

• Surgery: Surgical reduction (mastectomy or liposuction, depending on whether the tissue is glandular or fatty) is the most definitive treatment. NHS access to surgery for gynaecomastia is subject to local Integrated Care Board (ICB) commissioning policies, and many ICBs restrict funding to cases where there is documented psychological harm or significant physical symptoms.^[2] Policies vary between ICBs, so your GP or specialist can advise on local eligibility criteria. A GP referral to a breast surgeon or endocrinologist is the starting point.

Private surgical options are available for those who do not meet NHS criteria, though costs vary considerably. Patient information from organisations such as BAPRAS (British Association of Plastic, Reconstructive and Aesthetic Surgeons) can help set realistic expectations about surgical outcomes and risks. A GP can advise on the referral pathway most appropriate for your circumstances.

Can lifestyle changes help reduce man boobs without surgery?

Lifestyle changes such as a calorie-controlled diet and regular exercise can reduce chest size when excess fat is the main cause, but are unlikely to resolve true glandular gynaecomastia on their own.

Lifestyle changes can meaningfully reduce chest size in men whose breast appearance is primarily due to excess body fat (pseudogynaecomastia), though they are less effective at shrinking true glandular breast tissue once it has developed. Understanding which type is present, ideally confirmed by a GP or specialist, helps set realistic expectations for what lifestyle modification can achieve.

For men with a significant fatty component, the following approaches are supported by general evidence on weight management:

• Calorie-controlled diet: Reducing overall energy intake to achieve a gradual, sustainable reduction in body fat. There is no specific food that targets chest fat, but a balanced diet lower in ultra-processed foods and added sugars supports overall fat loss.

• Resistance and cardiovascular exercise: Strength training builds pectoral muscle beneath the breast tissue, which can improve chest contour, while aerobic exercise supports overall fat reduction. Neither targets chest fat exclusively, but both contribute to body composition changes over time.

• Reducing alcohol intake: Alcohol can affect hormone metabolism and contribute to weight gain; reducing consumption in line with NHS Chief Medical Officers' low-risk drinking guidelines (no more than 14 units per week, spread across several days) may help.^[3][4]

• Avoiding anabolic steroids and cannabis: Anabolic steroids are a well-established cause of gynaecomastia. Cannabis has been associated with gynaecomastia in some reports, though the evidence remains limited; avoiding it is a reasonable precaution.

For men whose gynaecomastia has a hormonal or glandular basis, lifestyle changes alone are unlikely to resolve the condition fully, though they remain beneficial for general health. NHS Better Health offers free weight management resources and support tools that may be helpful for men looking to reduce body fat. Weight management services, including clinically supervised programmes, may be appropriate for some men. Bolt Pharmacy is a GPhC-registered UK online pharmacy offering online weight-management consultations, with prescriber review and pharmacist support, where a range of clinically appropriate options may be considered. Discussing your specific situation with a GP remains the most important first step.

Scientific References

1. Gynaecomastia.
2. Breast reduction (male).
3. Drink less alcohol – Better Health.
4. Alcohol consumption: advice on low risk drinking.
5. Suspected cancer: recognition and referral (NG12).
6. EAA clinical practice guidelines – gynecomastia evaluation and management.
7. Gynecomastia and cirrhosis of the liver (JAMA).
8. Gynecomastia and cirrhosis of the liver (PubMed).
9. 17Beta-hydroxysteroid dehydrogenase type 2 and dehydroepiandrosterone sulfotransferase in the human liver.
10. Treatment of testosterone-induced gynecomastia with the aromatase inhibitor, anastrozole.
11. Gynecomastia and hormones.
12. Anabolic steroid-induced hypogonadism: diagnosis and treatment.
13. Male Reproductive Endocrine Disorders.
14. Endocrine disorders associated with inappropriately high aromatase expression.
15. Aromatase in human breast carcinoma.
16. An Unusual Case of Gynecomastia Associated With Subclinical Hyperthyroidism.
17. The interrelationships between thyroid dysfunction and hypogonadism in men and boys.
18. Gynecomastia as a presenting symptom of Graves' disease in a 49-year-old man.
19. Breast cancer in men.

Frequently Asked Questions