Finasteride for Hair Loss: How It Works, Who It Is For, and What to Expect

Finasteride is the most researched hair loss medicine on the market and the most prescribed oral treatment for male pattern hair loss in the UK. It is MHRA licensed for use in men aged 18 to 41 at 1mg daily under the brand name Propecia and several generic equivalents (Accord, Aristo, Teva). This guide covers every UK brand you might be dispensed, the licensed and off-label uses, the clinical evidence behind the drug, real side effect rates, cost comparisons, and how finasteride sits alongside dutasteride and topical alternatives.

Finasteride brands available in the UK

Every UK finasteride 1mg tablet contains the same active ingredient at the same dose. What differs is the manufacturer, the tablet appearance and the price. Any UK prescriber will confirm these are clinically interchangeable.

• Propecia (Merck): the original branded finasteride 1mg. The first finasteride licensed for hair loss (MHRA 1998, FDA 1997). Now typically the most expensive option per tablet, often £35 to £60 for 28 tablets at UK retail. Same active as every generic below.
• Finasteride Accord 1mg (Accord Healthcare): a UK generic manufactured by Accord, one of the most commonly dispensed brands in NHS pharmacies. Same 1mg dose, similar oval film-coated tablet. See our Accord Finasteride 1mg product page for pricing.
• Finasteride Aristo 1mg (Aristo Pharma): German-based generic manufacturer, MHRA licensed for the UK. Same 1mg dose.
• Finasteride Teva 1mg (Teva UK): another common UK generic option, dispensed against prescription across UK pharmacies.
• Generic finasteride 1mg (mixed manufacturers): UK pharmacies routinely dispense whichever generic is in stock, all MHRA licensed and clinically equivalent. Our generic Finasteride 1mg starts at £15 for a monthly 28 tablet pack, falling to 36p per tablet on a 12 month value pack.
• Finasteride 5mg tablets (multiple UK generics): MHRA licensed for benign prostatic hyperplasia (BPH), NOT for hair loss. Sometimes prescribed off-label for hair loss at a reduced dose set by the prescriber, which can make it the lowest-cost option per month (~£10 to £14 on our 4 and 12 month packs). The dose is decided at prescriber review, not self-managed. See our Finasteride 5mg tablets.

How finasteride works for hair loss

Finasteride is a Type II 5-alpha reductase inhibitor. In plain English: the enzyme 5-alpha reductase converts testosterone into dihydrotestosterone (DHT) inside your body. DHT is the hormone that shrinks (miniaturises) hair follicles in men with a genetic predisposition to male pattern hair loss. Less DHT means less follicle miniaturisation, which means existing follicles stay productive longer and some previously miniaturised follicles can recover.

Key numbers on the mechanism:

• Finasteride 1mg daily reduces serum DHT by roughly 70 percent. Scalp DHT falls in parallel.
• Effect on serum testosterone is minimal, typically a small increase within normal reference range.
• Peak DHT suppression is reached within 24 hours of the first tablet. Sustained daily dosing keeps DHT suppressed.
• DHT levels start returning to baseline within 24 to 48 hours of stopping. Any hair gained is lost over 6 to 12 months once treatment is discontinued.

This is why finasteride is a maintenance treatment, not a course. Gains persist only while treatment continues.

Licensed vs off-label uses in the UK

Finasteride has two MHRA licensed uses in the UK, at two different strengths:

• 1mg daily (Propecia and generics) is MHRA licensed for the treatment of male pattern hair loss in men aged 18 to 41. This is the on-label use for hair.
• 5mg daily (Proscar and generics) is MHRA licensed for benign prostatic hyperplasia (BPH) in older men. This is NOT a licensed hair loss dose.

Off-label uses commonly prescribed by UK prescribers:

• Finasteride 5mg at a reduced off-label dose for hair loss. Because the dose-response curve for scalp DHT suppression plateaus around 1mg (see clinical evidence below), there is no hair-loss benefit to dosing above 1mg, and some UK prescribers use the cheaper 5mg tablet at a lower dose they set for the individual. The strength and schedule are a prescriber decision, not a self-managed one.
• Finasteride for women over 45 or post-menopausal women under specialist supervision. Not the standard first-line female treatment (spironolactone or topical minoxidil is), but sometimes used when other options have failed.
• Topical finasteride (compounded solution applied to the scalp). MHRA has never licensed a topical finasteride product, so all topical finasteride in the UK is prescribed off-label as a Special (a compounded medicine prepared to individual prescription). See our FINASOL topical finasteride.

Off-label prescribing is legal and common practice in the UK when a prescriber judges it appropriate for the individual patient.

Clinical evidence: the trials behind finasteride

Finasteride has 25+ years of clinical evidence at doses relevant to hair loss. The trials that matter:

• Original Merck 5 year trials (Kaufman et al 1998, published in the Journal of the American Academy of Dermatology): 1,879 men with male pattern hair loss randomised to finasteride 1mg or placebo. At 2 years: 66 percent of treated men had increased hair count versus 7 percent on placebo, and 83 percent maintained or improved vs 28 percent on placebo. Effect sustained at 5 years. This is the trial that supported the MHRA 1998 licence.
• Roberts et al 1999 dose-response study: compared finasteride 0.2mg, 1mg, 5mg and placebo daily in men with androgenetic alopecia over 12 months. The 1mg and 5mg doses produced clinically similar hair count improvements, both significantly better than 0.2mg and placebo. The practical point: higher doses do not out-perform 1mg for hair, so there is no benefit to dosing above 1mg.
• Rossi et al 2011 long term follow up (10 years): Italian cohort of 118 men on finasteride 1mg daily. 86 percent had clinical improvement or stabilisation at 10 years. Adverse events at 10 years were similar to placebo comparator groups. This is the strongest published evidence that finasteride works over the long haul, not just the initial 1 to 2 years.
• Sato et al 2012 meta-analysis: pooled 12 randomised trials of finasteride 1mg in men, confirming ~9 to 10 percent increase in hair count at 1 year and ~15 to 18 percent at 2 years. These are the numbers you see quoted in most hair loss content.

Practical takeaway: finasteride is the most rigorously evidenced oral hair loss treatment. Response rates are high but not universal (roughly 15 percent of men are true non-responders at 1 year). If finasteride 1mg has not moved the needle at 12 months, the next options are dutasteride 0.5mg (stronger DHT block) or combination with minoxidil.

How long does finasteride take to work?

Finasteride is not a short course. It takes months for follicles to respond and the growth cycle to shift towards fewer miniaturised hairs. Expected timeline:

• Weeks 1 to 4: no visible change. Serum DHT is falling by 70 percent but hair does not respond in real time.
• Months 3 to 6: reduced shedding is the first visible sign. You may notice fewer hairs in the shower drain or on your pillow. Visible thickness gains are still weeks away.
• Months 6 to 12: first visible hair count improvements. Full thickness gains are typically judged at 12 months of consistent daily use.
• Months 12 to 24: continued gradual improvement. Peak effect is usually reached at 2 years.
• Years 2 to 10: maintenance. Gains slowly plateau but consistent daily use maintains them.

Missing occasional days: fine, resume the next day. Missing multiple days per week: your DHT suppression is not sustained and you will underperform the trial results. Consistency is more important than the specific time of day.

Side effects: the honest picture

Finasteride is generally well tolerated in the trial data. The published side effects, in order of frequency:

• Sexual side effects. In the trials supporting the licence, at 12 months against placebo: decreased libido 1.8% versus 1.3%, erectile dysfunction 1.3% versus 0.7%, and ejaculation disorder (mainly reduced volume) 0.8% versus 0.4%. By year five each of these had fallen below 0.3%. Note how much of the reported rate also appeared in the placebo arm, which is a genuine feature of this data. Reports are usually mild and reversible on stopping, and some men find they resolve while continuing treatment.
• Breast tenderness or enlargement (gynecomastia): rare, roughly 0.5 percent incidence. Usually resolves on stopping.
• Mood changes (low mood, depression, anxiety): reported in post-marketing surveillance but low frequency in trials. Take seriously if it develops; discuss with prescriber.
• Testicular pain: rare.
• Allergic reactions: uncommon rash, pruritus.

On post-finasteride syndrome (PFS): a small subset of men report persistent sexual, mood or physical side effects that continue after finasteride has been discontinued. The published incidence is very low and the mechanism is not fully understood. UK prescribers acknowledge PFS as a real (though uncommon) concern. If you develop side effects on finasteride, tell your prescriber immediately rather than waiting; early discontinuation is associated with better resolution outcomes. If you are worried about PFS specifically before starting, topical finasteride (lower systemic exposure, roughly one-third the sexual side effect rate in Piraccini et al 2022) is a lower-risk alternative.

Psychiatric side effects and the May 2026 MHRA position

On 11 May 2026 the MHRA issued updated safety warnings covering both finasteride and dutasteride. The current regulatory position is that these medicines are associated with depression, suicidal ideation and sexual dysfunction which may persist after treatment is stopped.

What this means in practice:

• Tell your prescriber if you have any history of depression or suicidal thoughts before starting. It does not automatically rule treatment out, but it must be weighed properly.
• If you develop depression or suicidal thoughts while taking finasteride 1mg, stop taking it and seek medical advice.
• UK finasteride packs carry a patient alert card, introduced in 2024, covering these risks. Read it, and read the leaflet inside your pack.
• Suspected side effects can be reported directly to the MHRA through the Yellow Card scheme.

If you are in crisis, contact your GP, call 111, or call Samaritans free on 116 123.

Finasteride vs the alternatives

UK men researching hair loss treatment have a limited but effective set of options. Here is where finasteride fits:

• Finasteride 1mg oral (this guide): the MHRA licensed first-line oral treatment for male pattern hair loss. Reduces serum DHT by ~70 percent. Roughly £15 to £22 per month at UK generic prices.
• Dutasteride 0.5mg oral: stronger DHT blocker (both Type I and Type II 5-alpha reductase, ~90 to 98 percent DHT reduction). Off-label for hair loss in the UK. Better hair count outcomes in head-to-head trials, but a longer half-life (5 weeks vs finasteride 6-8 hours) means side effects take longer to resolve on stopping. See our Dutasteride 0.5mg. See also our full finasteride vs dutasteride comparison.
• Topical finasteride (FINASOL): the same finasteride active applied to the scalp rather than swallowed, in a 100ml TrichoSol® bottle. Roughly one-third the sexual side effect rate of oral finasteride at similar hair count outcomes (Piraccini et al 2022). Off-label in the UK. See our FINASOL topical finasteride or the full topical vs oral finasteride comparison.
• Minoxidil (topical 2 to 15 percent or oral 2.5 to 5mg): a different mechanism (potassium channel opener, extends anagen phase, growth stimulator). Works alongside finasteride, not instead of it. The classic evidence-backed male regimen is oral finasteride 1mg plus topical minoxidil 5 percent. See our Topical Minoxidil or oral minoxidil 5mg.
• OTC "hair growth" supplements (biotin, saw palmetto, DHT-blocker herbal blends): weak to no evidence. No published RCT shows biotin or saw palmetto matches finasteride 1mg for hair count. Save your money.

What NOT to combine: never take finasteride and dutasteride together (two DHT blockers, no meaningful additional benefit, higher side effect risk). Never take oral finasteride with topical finasteride (same drug, two routes, stacks the dose). Minoxidil with finasteride is fine and encouraged; these are different drugs with different mechanisms.

Dosage

The MHRA licensed hair loss dose is 1mg per day, once daily, at any consistent time. With or without food. Two minutes of effort per day.

If you miss a dose: take it when you remember if it is still the same day. If you only remember the following day, skip it and take the next one at the normal time. Never take two to make up for one. A single missed day makes very little difference, because DHT suppression outlasts the drug itself; a regular pattern of missed days will slow your progress.

A lower-cost off-label route. Some UK prescribers use the 5mg tablet (licensed for BPH, not hair loss) at a reduced dose to bring the monthly cost down, since the evidence shows no added hair-loss benefit above 1mg. The right dose and how to take it are set by your prescriber for you individually, not worked out from a web page. If cost matters to you, raise the off-label 5mg option at prescriber review and follow the dose they set. See our finasteride 5mg page.

Higher doses (2mg, 5mg, 10mg daily) do NOT produce faster or better hair growth. The dose-response plateau is around 1mg for scalp DHT suppression, so taking more just increases side effect risk with no additional benefit.

Storage and shelf life

• Store at room temperature (below 25°C), away from direct sunlight and moisture.
• Keep tablets in their original blister pack or bottle until you take them. The blister foil protects the tablet from moisture and light.
• Sealed pack expiry is on the label (typically 24 to 36 months from manufacture). Do not use after the printed expiry date.
• If your prescriber has directed you to split tablets, store the cut pieces in the original closed bottle and use them within 2 weeks, as the cut edge can oxidise once exposed to air.
• Keep out of reach of children, pets, and anyone pregnant or planning pregnancy. Broken tablets can transfer finasteride through the skin, and finasteride is contraindicated during pregnancy.

Excipients: what is in a finasteride 1mg tablet

Active ingredient: finasteride 1mg. Typical excipients in UK generic finasteride 1mg tablets:

• Lactose monohydrate as the primary filler. If you are severely lactose intolerant, ask your prescriber about lactose-free brands.
• Microcrystalline cellulose, pregelatinised starch, sodium starch glycolate, magnesium stearate as tablet binders, disintegrants and lubricants.
• Docusate sodium as a wetting agent.
• Talc, hypromellose, titanium dioxide and yellow / brown iron oxides in the film coating.

The full excipient list is on the manufacturer Patient Information Leaflet enclosed with your medicine. Different brands (Accord, Aristo, Teva, Milpharm, generic) use slightly different excipient combinations; the active is identical.

Regulatory status: POM, MHRA licensed since 1998

• Finasteride is a prescription only medicine (POM) in the UK at every strength. There is no over the counter finasteride.
• Propecia (finasteride 1mg) has been MHRA licensed for male pattern hair loss since 1998. Generic finasteride 1mg tablets are MHRA licensed to the same clinical file.
• Proscar (finasteride 5mg) has been MHRA licensed for BPH since 1994. The 5mg strength is NOT licensed for hair loss; using it for hair loss is off-label prescribing.
• Free UK prescriber review at checkout: the online medical questionnaire is reviewed by a UK GPhC registered prescriber before dispensing. This assesses eligibility, PFS history, and contraindications.
• Dispensed by a GPhC registered UK partner pharmacy. Every pack we sell is prepared and shipped in the UK.

Patient Information Leaflets and further reading

• Propecia 1mg PIL (medicines.org.uk): the branded manufacturer patient information leaflet.
• NHS: Finasteride: NHS patient information page.
• NICE CKS: Hair loss (androgenetic, male and female pattern): UK clinical summary for prescribers.
• MHRA Drug Safety Update: finasteride and dutasteride, updated safety warnings for psychiatric side effects and sexual dysfunction (11 May 2026): the current UK regulatory position.
• Finasteride 1mg Summary of Product Characteristics (eMC): the licensed product information, including adverse reaction frequencies.

Every pack we dispense ships with the manufacturer PIL enclosed. Always read the leaflet supplied with your medicine, and contact your prescriber or the pharmacy if anything is unclear.

Our Finasteride Treatments

Finasteride Accord 1mg Hair Loss Oral Treatment 28 Tablets

Accord Finasteride 1mg: prescription hair loss treatment that reduces DHT. One tablet daily. Results in 4–6 months. Free prescription included.

From £20.00

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FINASOL® Topical Finasteride in TrichoSol™: Hair Loss Treatment 100ml

Prescription topical finasteride, 100ml bottle in the TrichoSol® base by Fagron. Choose 0.025%, 0.05%, 0.1% or 0.2%. Optional minoxidil or tretinoin add-ons. Free UK prescription and delivery.

From £65.00

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Finasteride 1mg Hair Loss Oral Treatment

Finasteride 1mg is a prescription treatment for male pattern hair loss that works by reducing DHT. Take one tablet daily. Results in 4–6 months. Prescription included.

From £15.00

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Finasteride 5mg Oral Hair Loss Treatment

Finasteride 5mg, licensed for enlarged prostate and used off-label for male pattern hair loss at a reduced dose set by your prescriber. Lowers DHT, the hormone behind male pattern hair loss. Free prescription and UK delivery.

From £40.00

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Next steps

For the broader UK landscape and how finasteride fits with topical and combination approaches, see our complete UK hair loss treatment guide. Comparing finasteride against dutasteride, the alternative anti-androgen? Read our finasteride vs dutasteride comparison. Considering topical over oral for side effect reasons? See our topical vs oral finasteride guide.