Gynaecomastia and Finasteride: How Likely Is It, and Does It Go Away?

Yes, finasteride can cause gynaecomastia (growth of breast tissue in men), but it is uncommon. The UK product information lists breast tenderness and enlargement as a possible side effect of both the 1 mg hair loss tablet and the 5 mg prostate tablet. Most men never notice a change. If you do, the tenderness often settles after stopping, but established tissue may not shrink fully. Any hard lump, nipple discharge or skin change needs a GP to check it promptly.

How finasteride can change breast tissue#

Finasteride blocks an enzyme that turns testosterone into dihydrotestosterone (DHT). DHT is the hormone that shrinks hair follicles, which is why the drug helps with male pattern hair loss.

Blocking that step means less DHT and slightly more testosterone is left over. Some of that testosterone can be converted into oestrogen. In a few men, the balance between androgens (male hormones) and oestrogen tilts enough to stimulate the glands behind the nipple.

The change is small. Blood tests in men on finasteride usually stay within normal ranges, so a normal result does not rule the drug out as the cause. Our guide on whether finasteride lowers testosterone covers the hormone changes in more detail.

How likely is it on 1 mg and 5 mg?#

UK product information uses frequency bands. "Uncommon" means between 1 in 100 and 1 in 1,000 people. For the 5 mg tablet used for an enlarged prostate, breast tenderness and enlargement sit in that range. In the main 5 mg trials, a few men in every 100 reported breast changes, slightly more than on placebo.

For the 1 mg hair loss tablet, the wording differs by brand. Some leaflets list breast tenderness and enlargement as reported after the medicine was launched, so an exact rate is not known. Check the leaflet in your own box. In practice it is a rare problem at 1 mg, and a lower dose and younger age both make it less likely than in older men on 5 mg.

Other things matter too. Dutasteride, a similar medicine, carries the same type of warning. Topical finasteride puts much less into the blood, so the risk is probably lower, but it is not zero. Reports exist, and the research is thinner.

Is it gynaecomastia, fat or something else?#

Breast tissue growth is common in men without any medicine. Many cases have no clear cause. Weight gain, cannabis, anabolic steroids, some heart and stomach medicines and some antidepressants can all do it. Work out what you are feeling first.

This table is a rough guide only. You cannot reliably tell the difference by looking, so a clinician needs to examine you.

Why a lump should be checked quickly#

Male breast cancer is rare, but cases have been reported in men taking finasteride. The MHRA has asked men on finasteride to report breast changes promptly. These include lumps, pain, nipple discharge or nipple retraction. A causal link has not been proven, but checking early costs you little.

If you find any of these signs, book a GP appointment and tell them you take finasteride. Whether to stop the tablets while you wait is a decision for you and your prescriber. Many will advise pausing while you are assessed.

Will it go away if you stop?#

Often, partly. Tenderness usually eases within a few weeks of stopping. Swelling can take several months to shrink.

Timing matters because breast tissue changes over time. In the first months it is mainly active, growing gland, which can regress once the trigger is removed. After roughly a year it tends to become scarred, fibrous tissue, which does not usually shrink on its own. Case reports describe men whose breast tissue stayed even after a short course of low-dose finasteride.

That is why it is worth acting early rather than waiting to see if it passes.

What your GP may do#

A GP will ask about your medicines, alcohol, drugs and any family history of breast problems. They will examine your chest and may check your testicles too. They may arrange blood tests for hormones, liver and kidney function and thyroid. NICE clinical knowledge summaries guide this work.

You may be referred to a breast clinic if there is a lump or anything unusual. Endocrinology referral is possible if hormone results are abnormal. This is also the route for ultrasound or a scan.

If gynaecomastia persists:

• Tamoxifen is sometimes used by specialists for painful, recent-onset cases. It is off-label for this use in the UK.
• Surgery is rarely funded by the NHS for cosmetic reasons. Local criteria are strict and usually need pain, a clear medical cause or major distress. Private surgery often costs roughly £3,000 to £6,000, depending on the surgeon and technique.

You can also report a suspected side effect yourself through the MHRA Yellow Card scheme (search "Yellow Card" online or use the app). You do not need a doctor to do it. Reports help the MHRA spot patterns that individual cases cannot show.

Options if you want to avoid the risk#

Minoxidil is applied to the scalp and does not act on sex hormones, so it does not carry this breast risk through the same route. It is a reasonable alternative for some men, though it works differently. Our comparison of finasteride and minoxidil explains the trade-offs. Topical finasteride is another option some prescribers discuss.

If you stay on finasteride, the MHRA also asks prescribers to give a patient reminder card. It covers mood changes and sexual side effects as well as breast changes. Our page on finasteride side effects goes through the full list.

If you are weighing this up before starting, or you are worried about a change you have noticed, a pharmacist or prescriber can talk through the options with you. Totiva's hair loss service supplies finasteride 1 mg (28 tablets for £9.49) and minoxidil after a free clinician review, and the team can help you decide what suits you.