Hair loss

What is finasteride used for?

Heard of finasteride but not sure what it actually does? Here’s what it’s prescribed for.

iconPublished 4th December 2025

Looking for ways to prevent hair loss? You’ve probably come across finasteride. It’s one of the main treatments for male pattern baldness in the UK. But that’s not the only thing it can help with.

So, what is finasteride used for in men? Read on to find out.

Key Takeaways

  • Finasteride works by blocking production of the hormone DHT
  • It’s used to treat an enlarged prostate and hair loss in men
  • The recommended dose for hair loss is 1mg, while it’s 5mg for an enlarged prostate
  • Finasteride isn’t available on the NHS for hair loss, but can be prescribed privately

What exactly does finasteride do?

Let’s get to it: what does finasteride actually do? It’s a type of medicine called a 5-alpha reductase inhibitor.

That means it works by blocking (inhibiting) the actions of 5-alpha reductase enzymes. These enzymes convert testosterone into another hormone called DHT. So, finasteride ultimately works to lower your DHT levels.

DHT can cause both abnormal prostate growth and hair loss, by gradually shrinking your hair follicles. Eventually, the follicles completely close up and hair stops growing.

Finasteride uses in men

With the above in mind, it’s probably no surprise that finasteride is licensed as a treatment for an enlarged prostate and hair loss. It’s also sometimes used off-label to treat signs of hyperandrogenism (excessive male hormones) in women.

But for men, here’s what finasteride is used for in the UK.

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Hair loss

Finasteride can prevent further hair loss while encouraging regrowth. It can increase your hair count and reverse the effects of DHT.

As a refresher: DHT gradually gets your hair follicles to close up, a process called miniaturisation. Meanwhile, your hairs grow progressively thinner and lighter in colour. Finasteride may be able to reverse this effect, so your hair grows back thicker and longer.

Enlarged prostate

Another thing DHT does is promote tissue growth and cell multiplication in the prostate. This can make the prostate grow larger—sometimes to the point where it’s abnormally big.

Good to know: benign prostate hyperplasia is the official term for this. It’s common, especially in men aged over 50.

If your prostate is too big, it can cause urinary issues like trouble peeing or feeling that you need to pee all the time.

Finasteride can reduce prostate size and ease urinary symptoms.

Finasteride 1mg vs 5mg tablets: What’s the difference?

Finasteride 1mg is the recommended dose for hair loss, while 5mg is for an enlarged prostate.

Why the difference matters for hair loss:

Taking a higher dose (5mg) won't improve hair growth results - it only increases the risk of side effects. The 1mg dose is optimised to deliver maximum hair regrowth benefits while minimising side effects.

Possible side effects (not everyone experiences these):

  • Difficulties having an erection
  • Lower libido
  • Problems with ejaculation, such as less sperm being released during sex
  • Breast swelling (gynaecomastia)
  • Low mood and depressive symptoms

Most people tolerate finasteride well. If you do experience side effects, they're typically mild and often improve over time. Your clinician will monitor your response and adjust treatment if needed.

What about pregnancy and fertility?

Talk to your provider before starting finasteride if your partner is pregnant, planning to become pregnant, or if you're actively trying to conceive.

While the amount of finasteride in semen after a 1mg dose is extremely small and unlikely to cause harm, we recommend using a condom as a precaution if your partner is pregnant.

Long-term data on finasteride's impact on male fertility is limited. Most evidence suggests it's safe but some isolated reports exist of temporary changes in sperm quality that normalised after stopping treatment. If you have existing fertility concerns, discuss these with your clinician before starting.

Why would a doctor prescribe finasteride?

For hair loss, a doctor might prescribe you finasteride if:

  • You have male-pattern hair loss, aka hereditary hair loss
  • You have mild-moderate hair loss. It won’t work if your follicles are completely closed up

And if you’ve got an enlarged prostate, finasteride may be suggested if you’re getting urinary symptoms that don’t go away, are bothering you or are becoming worse.

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Finasteride use in the UK

Finasteride isn't available on the NHS for hair loss, as it's considered cosmetic. But research shows hair loss affects far more than appearance. In a survey of over 700 men across Europe experiencing hair loss, 62% said it affected their self-esteem, 22% reported negative effects on social life and 21% experienced feelings of depression.

You can get finasteride privately through registered online providers and clinics. Always check if a provider is registered on their website: pharmacies should be registered with the General Pharmaceutical Council (GPhC) while clinics should be registered with the Care Quality Commission (CQC). This information is usually on their footer—scroll down to see ours.

At MANUAL, we offer finasteride as part of our cutting-edge hair loss programme. It’s backed by science and powered by expert clinicians. And it can help you get your hair back.

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FAQ

What is finasteride used for? FAQ

DisclaimerAt MANUAL, we ensure that everything you read in the Health Centre is medically reviewed and approved. However, the information provided is not meant to replace professional medical advice, diagnosis, or treatment. It should not be relied upon for specific medical advice.
References
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“Enlarged prostate,” NHSscribble-underline, 2025. www.nhs.uk/conditions/enlarged-prostate/. Accessed 10 Nov. 2025.

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Gupta, Aditya, et al. “Relative Efficacy of Minoxidil and the 5-α Reductase Inhibitors in Androgenic Alopecia Treatment of Male Patients, A Network Meta-analysis,” JAMA Dermatologyscribble-underline, vol. 158, no. 3, 2022:266-274 https://pmc.ncbi.nlm.nih.gov/articles/PMC8811710/.

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Smith, Angela B., and Carson, Culley C. “Finasteride in the Treatment of Patients with Benign Prostatic Hyperplasia: A Review,” Therapeutics and Clinical Risk Managementscribble-underline, vol. 5, 2009:535-545. https://pmc.ncbi.nlm.nih.gov/articles/PMC2710385/.

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“Side Effects of Finasteride,” NHS,scribble-underline www.nhs.uk/medicines/finasteride/side-effects-of-finasteride/. Accessed 10 Nov. 2025.

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