Finasteride vs dutasteride for hair loss

Finasteride and dutasteride are two prescription medicines from the same group, both taken by mouth once a day. This page is for men who take finasteride, or are thinking about it, and want to know whether dutasteride is stronger, riskier, or worth raising with a prescriber.

One large trial compared the two directly. Over six months dutasteride raised total hair count more than finasteride, and the advantage was not shown when only the thicker hairs were counted. ^[1] The rest of the comparison is about other things: where each is approved, how long each has been followed, how long it stays in the body and what regulators say about side effects. Below, the two are set side by side, and every number stays next to the study it came from.

What each medicine is and where it is approved

Both belong to the same group of medicines, called 5-alpha-reductase inhibitors, and both lower a hormone called DHT. What sets them apart for a man deciding is the form, the label and the evidence behind each. ^{[2, 11, 12]}

Finasteride for hair loss is a 1 mg tablet taken once a day, with or without food. It is approved in the United States and the United Kingdom for men with male pattern hair loss, on prescription. A 5 mg tablet of the same medicine is used for an enlarged prostate, and figures from that product do not carry over to the 1 mg dose. ^{[2, 3]}

Dutasteride in the US and UK is a 0.5 mg soft capsule approved for an enlarged prostate, not for hair loss. Taking it for hair there is an off-label use that a prescriber has to decide on. Japan is different: its label includes male pattern hair loss, at 0.1 mg once a day, or 0.5 mg if needed. ^{[4, 5, 6]}

Each medicine also exists in a form for the scalp: a finasteride spray authorised in some European countries, and a dutasteride solution that we know from one research trial. Those are separate questions with their own evidence. They are covered on the page about topical finasteride and in the dutasteride profile's section on the scalp solution. This page compares the tablet with the capsule. ^{[13, 11]}

The one large trial that compared them

Most of what is known about this comparison comes from a single trial. It randomly assigned 917 men aged 20 to 50 to five groups: three doses of dutasteride, finasteride 1 mg, or placebo, each taken once a day for 24 weeks. The three groups that matter here were 184 men on dutasteride 0.5 mg, 179 on finasteride 1 mg and 181 on placebo. In all, 761 of the 917 completed the trial. Hairs were counted on photographs, inside a circle 2.54 cm across at the crown. ^[1] Where the trials of both medicines counted hair, front or crown, is covered on the page about minoxidil and a receding hairline.

Both medicines raised total hair count more than placebo, and dutasteride 0.5 mg raised it more than finasteride 1 mg. The adjusted difference between the two was 33.0 hairs in that circle. It was reported with a range for the true difference of 6.1 to 60.0 hairs, a 99.165% confidence interval: wide, but clear of zero. ^{[1, 6]}

The trial also counted the terminal hairs, the thicker ones, on their own. Here the picture changes.

What the trial showed, and what it did not

It showed two things: more hair than placebo with both medicines, and a larger rise in total hair count with dutasteride than with finasteride at 24 weeks.

Two limits apply to the result itself. About one man in six did not finish, and for those men the analysis carried the last measurement forward. And of the 764 starting photographs that could be used, 71 were taken after treatment had begun. Neither cancels the finding. Both are reasons not to read the size of the gap as exact. ^[1]

What the network analysis adds

A network analysis pools many trials and combines direct comparisons with indirect ones. One published in 2022 pooled 23 studies of minoxidil, finasteride and dutasteride in men: 21 randomised trials and two observational studies. For total hair count at 24 weeks, it put the gap between dutasteride 0.5 mg and finasteride 1 mg at about 7 hairs per square centimetre, with a 95% confidence interval of 5.1 to 9.3. ^[14]

So is dutasteride better than finasteride

For total hair count at six months, the direct trial says yes: the average gain was larger. For thicker hairs it was not shown. For the result over several years, for the response of any one man and for the balance between benefit and side effects, the trial has no answer. Among the sources we reviewed, no direct comparison of the two medicines ran longer than 24 weeks. ^[1]

Dutasteride two or three times a week

Because dutasteride leaves the body slowly, some men ask whether it could be taken less often than every day. One small pilot study looked at that. Sixty men in Thailand, aged 21 to 60, were randomly put into three groups of 20 for 24 weeks: dutasteride 0.5 mg twice a week, dutasteride 0.5 mg three times a week, or finasteride 1 mg every day. ^[12]

Three times a week did better than twice a week. Neither schedule was shown to be better than daily finasteride. Sexual side effects were recorded in 2 of the 20 men on the twice-weekly schedule, 1 of 20 on three times a week and 3 of 20 on finasteride. Groups of 20 are far too small to show that one schedule causes fewer side effects than another. ^[12]

What the study lacked is a group taking dutasteride every day. So it cannot say whether a few capsules a week match one a day, or whether fewer capsules mean fewer side effects. It is a first look at two schedules and does not establish either of them.

What is known over five years

Both medicines are taken for years, so how long each has been followed matters as much as the six-month result. Here the two are not on the same footing.

Finasteride's main evidence is against placebo. Two trials summarised in the US label enrolled 1,553 men with thinning at the crown. After 12 months the men on finasteride 1 mg had 107 more hairs than the men on placebo in the measured patch, an area of 5.1 cm². That figure belongs to its own trials and its own patch of scalp, and cannot be lined up with the circle counts above. ^[2]

The two also differ on what is known after stopping. The US finasteride label says that the effect on hair reverses within 12 months of stopping. For dutasteride, no source we reviewed measured what happens to the hair after the last capsule. The medicine staying in the blood for months is not evidence that the regrowth stays too. ^{[2, 4]}

Side effects side by side

Three kinds of information sit behind this section, and they should not be mixed: what was counted in trials, what regulators warn about, and what is still not known. The aim here is to show where the two medicines differ. The page on finasteride side effects goes into that medicine in more depth.

Sexual side effects in the trials

The direct trial tracked sexual and breast-related side effects as a special category, over 24 weeks. ^[1]

Other studies counted in other ways.

Each row has its own definition, its own way of asking and its own time span, so the rows cannot be compared with each other or added up. The dutasteride trial of sexual function was small and funded by GSK. In the pooled analysis, the range around the finasteride figure ran from 1.2 to 2.3 times the placebo rate. For dutasteride it ran from 0.8 to 2.3 times: from slightly fewer events than placebo to more than twice as many. A range that wide does not show that there is no risk, and setting the two pooled figures side by side does not show a difference between the medicines. ^{[2, 15, 16]}

What these studies have in common is that most men in them did not report a sexual side effect.

Effects that continue after stopping

For finasteride, the US label and the UK medicines regulator both report sexual problems that continued after men had stopped the tablets. In May 2026 the UK regulator confirmed that sexual dysfunction with finasteride tablets can persist after treatment ends. The reports come from use after the medicine went on sale, so there is no reliable figure for how often it happens. ^{[2, 10]}

For dutasteride, the US label says that sexual side effects may continue after stopping and that the role of the medicine in this is not known. In the small trial of sexual function, four side effects were still present when treatment ended, and they cleared within six weeks of the last capsule. That describes those men. It does not rule out longer-lasting problems in others. ^{[4, 15]}

For neither medicine can anyone give an honest percentage.

Mood warnings are not the same for the two

The difference lies in what the regulators concluded, and it should not be flattened in either direction. A precaution is not a finding that dutasteride is free of the risk, and it is not the confirmed association that applies to finasteride. Neither notice gives a figure for how often. ^{[9, 10]}

Semen measures and fertility

For each medicine we reviewed one study of semen in healthy volunteers. They are separate studies, not a comparison of one medicine with the other.

In the dutasteride study, which is reported in the US label, the average sperm count was still 23% below its starting level 24 weeks after the last capsule. Two men had falls of more than 90%, with partial recovery. The label says the effect on a man's fertility is not known. Neither study looked at pregnancies or births, and the finasteride result does not answer the question for men who already have a fertility problem. ^{[17, 4]}

None of these sources gives a waiting time before trying for a child. That question belongs with the leaflet of the product in hand and with the prescriber. The US finasteride label also warns against use in pregnancy and against contact with crushed or broken tablets, and the US dutasteride label warns that the medicine can be absorbed through the skin from a leaking capsule. Both medicines lower PSA, a blood marker used to check the prostate. The finasteride and dutasteride profiles cover those points. ^{[2, 4]}

How long each stays in the body

This is the plainest difference between the two. Half of a dose of finasteride is gone from the blood in five to six hours, in men aged 18 to 60. Once dutasteride has been taken for a while, half of it is still in the blood about five weeks after the last capsule, and it can be detected for four to six months. ^{[2, 4]}

Can you take both, or switch

The two medicines are alternatives. Dutasteride is not an automatic next step after finasteride, and the sources we reviewed support no combination of the two and no schedule for moving from one to the other.

Two facts about finasteride bear on the impression that it is not working. The US label says a benefit generally takes three months or more of daily use, and the trials counted hair at 6 and 12 months. And a gap over placebo can come from hair that was kept as well as hair that was gained, which is harder to see in a mirror. ^{[2, 1]}

For the wider question of what goes with what, see what to combine and what to choose between.

What each one costs

These are single prices we recorded on 29 September 2026, one offer per product, worked out for 30 days at the labelled dose of finasteride and at the dutasteride dose used in the direct trial. They are examples, not national averages, and we do not convert between currencies. We recorded no US price for dutasteride.

Over a year, the UK examples come to about £115 for finasteride and about £219 for dutasteride, before fees. The US finasteride example comes to about $324. In this one UK check, 30 days of dutasteride cost £17.98 against £9.46 for generic finasteride, before fees. The two offers differ in pack size and in the fees we could confirm. Price says nothing about which works better, and one offer each is not a market.

Where each sits in our ranking, and why

In our ranking of six ingredients, finasteride is listed second, in the top tier, which it shares with minoxidil. Our review does not establish a winner between those two. Dutasteride is third, in a tier of its own, as a conditional alternative.

That is not because it works less well. In the one large direct trial we reviewed, it raised total hair count more. ^[1] A position weighs eight criteria together, and effectiveness is one of them. What places dutasteride one tier lower is the rest of the decision:

The position is not fixed. It would be reopened by longer-term evidence on how dutasteride's benefits and risks compare, for the people and the country concerned. Where hair loss is on the label, as in Japan, the practical context is already different, and that does not change what the trial found. The criteria are explained under how we rank and on the methodology page.

Where to go next

Each medicine has a full profile with its trials, labels, side effects and costs in more detail. If the choice is really between a tablet and something for the scalp, the comparison to read is minoxidil vs finasteride. For all six ingredients at once, see the comparison in the main guide, or let the hair questionnaire point to a page. It does not diagnose anything.