Finasteride for Hair Loss: Does It Work, and Is It Safe?
Last reviewed on 1 August 2026. We review our treatment guides every six months to keep them accurate.
Finasteride is the best known prescription medicine for male pattern hair loss, and the questions people ask most are simple ones: does finasteride work for hair loss, and is it safe? This guide answers both honestly. It explains what finasteride is, how well it works and how long it takes, the difference between the 1mg hair loss dose and the 5mg prostate dose, what the side effects are and how common they are, and what UK regulators now advise. It is general information rather than medical advice, so please speak to your GP, a dermatologist or a prescriber about your own situation.
Finasteride is sold under the brand name Propecia for hair loss, and also as a generic. It is a genuinely effective treatment for many men, but it carries real risks that have been the subject of strengthened safety warnings, so it is worth understanding both sides before making any decision. For the current UK safety position, the medicines regulator, the MHRA, publishes a drug safety update on finasteride, and the NHS page on finasteride is a good independent starting point. Both are updated over time, so they stay current between our own reviews.
What is finasteride, and how does it work?
Finasteride belongs to a group of medicines called 5-alpha-reductase inhibitors. It works by blocking the type 2 form of 5-alpha-reductase, the enzyme that converts testosterone into dihydrotestosterone (DHT). In men who are genetically susceptible, DHT binds to receptors in scalp hair follicles and gradually shrinks them, a process called miniaturisation, so the hairs they produce become finer and shorter until, in time, they may stop growing altogether. Taken as the 1mg daily tablet, finasteride reduces the amount of DHT in the blood by around 70 per cent, which is intended to slow that process and, in some men, allow a degree of regrowth where follicles are still active.
Finasteride 1mg or 5mg? The dose that treats hair loss
In the UK the 1mg tablet (Propecia) is licensed for male pattern hair loss; the 5mg tablet (Proscar) treats an enlarged prostate, not hair loss.
This is one of the most common points of confusion, so it is worth being clear. In the UK, the 1mg tablet (Propecia) is the strength licensed to treat male pattern hair loss in men. The 5mg tablet (Proscar) is a different, higher-strength product licensed to treat an enlarged prostate, not hair loss. Searches for finasteride 5mg for hair loss usually come from this mix-up: 5mg is the prostate dose, and taking a higher dose does not produce better hair results, it only raises the risk of side effects. Some prescribers use lower doses, such as 0.5mg, but these are off-label variations that a doctor may consider in particular circumstances. This page does not give dosing instructions; the dose is a decision for your prescriber.
Finasteride is not licensed for use in women or children. It is also available in a topical form applied to the scalp, which we cover in our guide on topical versus oral finasteride. The important point is that topical finasteride is still absorbed and still lowers DHT in the blood, so it is not a version of the tablet without systemic effects.
Does finasteride work for hair loss?
For most men who take it, yes, though it is better at holding on to hair than at growing large amounts back. In the manufacturer's five-year trials, the large majority of men taking finasteride either kept the hair they had or improved, while men taking a dummy tablet continued to lose ground over the same period. In practice that means finasteride's main job is to slow or stop further loss, with some regrowth, particularly at the crown, for a proportion of men. It is realistic to think of it as a way to keep your hair rather than a way to restore a full head of hair.
Two things are worth being clear about. First, finasteride cannot revive follicles that have already been lost, so it works best when started while there is still hair to protect. Second, it only works for as long as it is taken. If the medicine is stopped, DHT rises again and hair loss resumes, with any ground gained gradually lost, usually within around a year.
Finasteride results: what to expect and when
Results are gradual, and the timeline below is a realistic general guide rather than a promise. Individual outcomes vary.
First few months: little visible change while the medicine takes effect. Some men notice a temporary increase in shedding early on as follicles reset their growth cycle. This is common and not a sign the treatment is failing.
Three to six months: reduced shedding tends to become noticeable, and for some men early regrowth begins, often first around the crown.
Around six to twelve months: the fuller effect is usually clearer, with any improvement in density and thickness more established. This is generally when it is fair to judge how much the medicine is doing for you.
Finasteride is not equally suited to every kind of hair loss. It is a treatment for male pattern hair loss (androgenetic alopecia), and it is not a treatment for other causes such as alopecia areata or telogen effluvium, which work in different ways.
How safe is finasteride? Side effects and warnings
Many men take finasteride without any trouble, but it does carry real risks, and these have been the subject of strengthened UK safety warnings, so they deserve a careful and honest account rather than a reassuring one.
The best-known side effects are sexual: a lower sex drive, difficulty getting or keeping an erection, and problems with ejaculation. In the manufacturer's clinical trials, any sexual side effect was reported by about 3.8 per cent of men taking finasteride in the first year, compared with about 2.1 per cent of men taking a dummy pill, so the effect is real but affects a minority. Broken down, decreased sex drive affected about 1.8 per cent of men on finasteride against 1.3 per cent on placebo, and erectile dysfunction about 1.3 per cent against 0.7 per cent, and the rate fell with continued use rather than building up. Breast tenderness or enlargement can also occur. We cover this subject in depth in our guide on finasteride sexual side effects.
Two points deserve particular attention. First, in a minority of men, sexual dysfunction has been reported to persist after the medicine is stopped, a pattern often discussed online as post-finasteride syndrome. It is a genuinely reported phenomenon that regulators take seriously, but it is not fully understood. Second, finasteride has been linked with depression, anxiety and, less commonly, suicidal thoughts.
Because of these concerns, the UK medicines regulator, the MHRA, introduced a patient alert card into every pack of finasteride in 2024, and strengthened the warnings further in May 2026. The current advice includes one instruction worth stating exactly: if you develop depression or suicidal thoughts while taking finasteride 1mg for hair loss, stop taking it and contact your doctor as soon as possible. Aside from that specific situation, you should not stop or change a prescribed medicine without speaking to the person who prescribed it. You can read the current position in the MHRA drug safety update.
Finasteride, women and pregnancy
Finasteride is contraindicated in women, and this matters most in pregnancy. Because DHT is needed for the normal development of a male baby, finasteride can interfere with that development, in particular the external genitalia. For this reason a woman who is pregnant or who could become pregnant must not take finasteride and should not handle crushed or broken tablets, which is why the tablets are coated. If you take finasteride and are trying for a baby, the small amount that reaches semen is not expected to harm a pregnancy; we cover this in our guide on finasteride and trying for a baby.
Alternatives to finasteride
Finasteride is not the only option. Minoxidil is a topical treatment that stimulates hair growth by a different route and does not act on DHT, so it can be used instead of or alongside finasteride. Dutasteride is a more potent DHT blocker sometimes considered by a specialist where finasteride has not done enough, though it is not licensed for hair loss in the UK. Supplements marketed as natural DHT blockers have much weaker evidence behind them. Which, if any, is right for you is a decision for a GP or dermatologist.
Frequently asked questions
Does finasteride stop hair loss and regrow hair?
For most men it slows or stops further loss, and a proportion also see some regrowth, particularly at the crown. It is more reliable at keeping hair than at regrowing it, and it cannot bring back follicles that have already been lost. It works only while it is taken, so hair loss resumes if the medicine is stopped.
What is the difference between finasteride 1mg and 5mg?
The 1mg tablet (Propecia) is the strength licensed for male pattern hair loss in men. The 5mg tablet (Proscar) is a higher-strength product for an enlarged prostate, not hair loss. A higher dose does not improve hair results and only raises the risk of side effects, so 5mg is not the hair loss dose. The dose is a matter for your prescriber.
What is finasteride 0.5mg used for?
Some prescribers use doses below 1mg, such as 0.5mg, off-label, for example to see how a man tolerates the medicine. The 1mg dose is the licensed standard for hair loss. Whether a lower dose is appropriate is a decision for a doctor, not something to arrange yourself.
How long does finasteride take to work?
Results are gradual. Reduced shedding tends to become noticeable over three to six months, with the fuller effect usually clearer by around six to twelve months. Some men shed a little more hair early on, which is normal. It is generally fair to judge how well it is working at about a year.
Is finasteride safe?
Many men take it without trouble, but it is not risk-free. The main side effects are sexual (reduced sex drive, erectile and ejaculation problems) in a minority, and it has been linked with depression and, less commonly, suicidal thoughts, which is why the MHRA has strengthened its warnings and put a patient alert card in every pack. Whether it is a safe choice for you depends on your own health and history, which is a conversation to have with a prescriber.
Can women take finasteride?
Finasteride is not licensed for women and is contraindicated in pregnancy, because it can affect the development of a male baby. A woman who is or could become pregnant should not take it or handle crushed or broken tablets. It is occasionally used for female hair loss, but only off-label and under specialist supervision.
The bottom line
Finasteride is one of the few treatments proven to slow male pattern hair loss, and for many men it works well and without trouble, mainly by protecting the hair they still have. Set against that are real risks: sexual side effects in a minority, a link with depression and rarely suicidal thoughts, and a poorly understood possibility that some sexual side effects persist after stopping, all of which have led the MHRA to strengthen its warnings. It is not a decision to rush or to make from a web page. Hair loss is not a medical emergency, and the sensible course is an informed conversation with a GP, dermatologist or prescriber who can weigh the benefits and the risks for you.
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