Finasteride vs minoxidil vs dutasteride: risks
All three can help hair grow. Only the finasteride and dutasteride leaflets warn sexual side effects can last after stopping: post-finasteride syndrome.
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In trials, finasteride, minoxidil and dutasteride all kept or regrew more hair than a dummy treatment. Only the finasteride and dutasteride leaflets warn that sexual side effects can continue after stopping, a condition known as post-finasteride syndrome (PFS).
Most comparisons count hairs and stop there. In 2024 the UK regulator said the lasting sexual side effects of finasteride were “not well known by prescribers and patients”.
The story in 3 lines
- The finasteride and dutasteride leaflets warn that sexual side effects can continue after stopping (dutasteride leaflet).
- Minoxidil's UK prescribing information lists no sexual side effects (Regaine foam).
- Nobody has measured how often the side effects last: the finasteride leaflet says "frequency unknown" (finasteride leaflet). Patients call it PFS.
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Sam, in the UK, had used minoxidil on and off for a couple of years. It wasn’t really working, so he asked his GP, who suggested finasteride. The only warning, he says, was a link to an NHS web page saying he might get erection problems.
About three months in, he noticed changes to his penis and put the tablets in the bin. “I thought everything was going to go back to normal,” he says. Over the months that followed, it got worse.
How do finasteride, minoxidil and dutasteride work?
Finasteride and dutasteride lower DHT, a hormone linked to shrinking hair follicles. Minoxidil works another way. It began as a blood pressure tablet that grew body hair as a side effect.
- Finasteride
- A daily tablet, licensed in the UK for male pattern hair loss at 1 mg
- Dutasteride
- A daily capsule, licensed in the UK only for an enlarged prostate
- Minoxidil
- A foam or liquid for the scalp, sold without a prescription. Taking the tablets for hair isn't an approved use
For finasteride and minoxidil, the hair gained lasts only while you keep using them. The UK prescribing information says hair grown on finasteride is gone within a year of stopping. On minoxidil, it may go within a few months.
Can the side effects last after you stop?
For finasteride and dutasteride, the leaflets say they can. Both list erection problems, lower sex drive and problems with ejaculation. After each one, the dutasteride leaflet adds: “this may continue after you stop taking Avodart”. Its prescribing information says the role of dutasteride in this “is unknown”.
By April 2024 the UK medicines regulator had hundreds of reports of sexual problems with finasteride. In almost half, the problem was recorded as not resolved.
Side effects that carry on after stopping either finasteride or dutasteride are called post-finasteride syndrome. It can affect sex, mood and cognition. For some people it has lasted years after stopping. Nobody knows yet who will be affected, or whether it will ease.
Minoxidil’s UK prescribing information lists no sexual side effects. The ones it does list include headache, an itchy scalp and unwanted hair on the face or body.
Matt used dutasteride on his scalp for about eight months.
How often does it happen?
Nobody has measured how often side effects last after stopping. Reports to regulators come from men who had a problem. They can’t show how many took the drug with no problem at all.
Expectation can play a part too. In one small trial of finasteride for an enlarged prostate, 44 in 100 men who were told about sexual side effects reported one, against 15 in 100 who weren’t told. It only followed men while they were taking the tablets, so it says nothing about what happens after stopping.
The UK regulator’s review named this “nocebo” effect, and media attention, as possible reasons for the rise in reports.
In 2025, CBC Radio heard from men whose problems carried on after they stopped.
What can I do?
Ask before you start. Finasteride for hair loss isn’t prescribed on the NHS, so you’ll pay for a private prescription. Whichever medicine you’re offered, you can ask:
- What happens to my hair if I stop?
- For finasteride or dutasteride: the leaflet says sexual side effects can continue after stopping. What do you know about that?
- Do you need to know about my mental health? The UK regulator asks finasteride prescribers to check for a history of depression first.
- Is it licensed for hair loss? In the UK, dutasteride and minoxidil tablets aren’t.
These medicines help many people. If you have side effects, that’s a decision for you and your prescriber. There’s one exception. If you develop depression or suicidal thoughts on finasteride for hair loss, the UK regulator says to stop it straight away and contact your doctor as soon as possible. Samaritans are on 116 123, free, at any hour.
If something has already changed, our guide to post-finasteride syndrome explains the symptoms.
Report it: it helps everyone
A doctor’s note helps you. A report to the medicines regulator helps everyone else: it is how patterns get noticed.
- No proof needed. A suspicion is enough, even years after stopping.
- Where: the Yellow Card scheme in the UK, MedWatch in the US.
- Use the right words. If symptoms continued after stopping, write Post 5-alpha-reductase inhibitor syndrome (MedDRA 10082430).
Our reporting guide walks you through it
Common questions
How common are sexual side effects while taking finasteride?
In the year-long trials behind the US label, about 4 in 100 men on finasteride 1 mg reported one, against 2 in 100 on a dummy tablet. The UK leaflet lists the ones that continue after stopping as “frequency unknown”.
How long does dutasteride stay in the body?
For months. The US label says it can still be found in the blood up to 4 to 6 months after the last capsule. Men who take it are told not to give blood until 6 months have passed, so it can’t reach a pregnant woman through a transfusion.
What about sprays that mix minoxidil and finasteride?
They contain finasteride. In 2025 the US medicines regulator warned that finasteride is expected to pass through the skin into the blood. Most reports it had received about pharmacy-made finasteride for the skin said the side effects continued after stopping. Our guide to topical finasteride has more.
Sam says his only warning was that he might get erection problems. Before your first dose, ask what happens after the last one.
Sources
Every source below was checked on 10 October 2026.
- Propecia 1 mg tablets, summary of product characteristics (sections 4.2 and 4.8) and patient information leaflet (sections 2 and 4). Electronic Medicines Compendium.
- Propecia (finasteride 1 mg), US prescribing information: section 6.1, sexual adverse experiences in the 12-month trials, 3.8% of 945 men on finasteride and 2.1% of 934 on placebo; section 6.2, sexual dysfunction that continued after stopping. DailyMed.
- Avodart 0.5 mg soft capsules, UK summary of product characteristics (section 4.1, licensed for benign prostatic hyperplasia; section 4.8, “These adverse events may persist after treatment discontinuation. The role of dutasteride in this persistence is unknown.”) and patient information leaflet (section 4).
- Avodart (dutasteride), US prescribing information: section 5.5, no blood donation until at least 6 months after the last dose; section 12.3, detectable in serum for up to 4 to 6 months after stopping. DailyMed.
- Regaine for Men Extra Strength 5% scalp solution, summary of product characteristics. General Sales List. Section 4.2: regrown hair may disappear three to four months after stopping. Also the 5% scalp foam, summary of product characteristics. Section 4.8 lists no sexual side effects. Electronic Medicines Compendium.
- Minoxidil tablets, US prescribing information. Licensed for severe hypertension; body hair grows in about 80% of patients. “Use of minoxidil tablets, in any formulation, to promote hair growth is not an approved indication.” DailyMed. In the UK, Loniten tablets, summary of product characteristics (section 4.1, licensed only for severe hypertension).
- MHRA, Finasteride: reminder of the risk of psychiatric side effects and of sexual side effects (which may persist after discontinuation of treatment), Drug Safety Update, 29 April 2024. It had 426 Yellow Card reports of sexual dysfunction to 5 April 2024; almost half were recorded as not recovered or not resolved.
- MHRA, Safety review of finasteride: public assessment report, 2024, on media attention and the possible nocebo effect as reasons for increased signals. Contains public sector information licensed under the Open Government Licence v3.0.
- MHRA, Finasteride and dutasteride: updated safety warnings for psychiatric side effects and sexual dysfunction, Drug Safety Update, 11 May 2026. Finasteride 1 mg is not prescribed on the NHS. Stop it immediately and contact a doctor if depression or suicidal thoughts develop. Prescribers should ask about a history of depression or suicidal ideation.
- Kaufman KD, Olsen EA, Whiting D and colleagues. Finasteride in the treatment of men with androgenetic alopecia. J Am Acad Dermatol 1998;39(4 Pt 1):578-89. Two one-year trials, 1,553 men aged 18 to 41.
- Olsen EA, Dunlap FE, Funicella T and colleagues. A randomized clinical trial of 5% topical minoxidil versus 2% topical minoxidil and placebo in the treatment of androgenetic alopecia in men. J Am Acad Dermatol 2002;47(3):377-85. 48 weeks, 393 men.
- Gubelin Harcha W, Barboza Martínez J, Tsai TF and colleagues. A randomized, active- and placebo-controlled study of the efficacy and safety of different doses of dutasteride versus placebo and finasteride in the treatment of male subjects with androgenetic alopecia. J Am Acad Dermatol 2014;70(3):489-98. 24 weeks, 917 men.
- Mondaini N, Gontero P, Giubilei G and colleagues. Finasteride 5 mg and sexual side effects: how many of these are related to a nocebo phenomenon? J Sex Med 2007;4(6):1708-12. 120 men with an enlarged prostate, 107 completed; 43.6% of those counselled against 15.3% of those not, assessed at 6 and 12 months on treatment.
- US Food and Drug Administration, FDA alerts health care providers, compounders and consumers of potential risks associated with compounded topical finasteride products, 22 April 2025.
- Videos, Moral Medicine: interviews with Sam (12 June 2025; minoxidil and his GP from 2:22, the NHS link at 3:56, “I thought everything was going to go back to normal” at 8:52) and Matt (26 August 2026). CBC News, The Current, 25 March 2025.
- Photo: Editor182, Avodart, public domain, via Wikimedia Commons, served from this site.
This information does not replace medical advice. Talk to your doctor before you make any decision about your treatment.
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