Dutasteride vs Finasteride: What's the Difference?

November 2, 2026

Medically reviewed by Dr Mahalia Theau, AHPRA registered doctor. Last reviewed November 2026.

Finasteride and dutasteride are two oral medicines from the same drug family, and a common question is how they differ. In short, they block the same hormone pathway but in slightly different ways. I'll outline some key points about each medication, but it is important to note that which one is best for you depends on your hair situation, background medical history and circumstances. Deciding which medication to use for male pattern hair loss is a decision that should be made between you and your doctor. For background on the condition, see our guide to male pattern baldness.

The Short Answer

Both medicines lower dihydrotestosterone (DHT), the hormone linked to shrinking hair follicles, by blocking an enzyme called 5 alpha reductase.
Finasteride mainly blocks one form of that enzyme (type 2). Dutasteride blocks two forms (types 1 and 2), and trials measure a larger fall in blood DHT with dutasteride.
In 24 week head to head trials, the dutasteride groups usually had a larger average change in hair count.
The trials were short and mostly small, so long term comparisons are not available. Pooled sexual side effects were not statistically different between the two.
Finasteride 1 mg is registered in Australia for male pattern hair loss. Dutasteride is registered for prostate enlargement, so its use for hair loss is off label.
Finasteride leaves the body within about a day, while dutasteride can remain detectable for months, which matters when thinking about pregnancy planning, blood donation and stopping due to side effects.

Finasteride and dutasteride at a glance

	Finasteride	Dutasteride
Enzyme blocked	Mainly type 2	Types 1 and 2
Hair count in 24 week trials	Smaller average change	Usually larger, about 7 hairs per square centimetre pooled
Pooled sexual side effects	Not statistically different	Not statistically different
Australian registration	Registered for male pattern hair loss at 1 mg	Registered for prostate enlargement, so off label for hair loss
Time in the body	Leaves within about a day	Detectable for weeks to months

How the Two Medicines Work

Testosterone is converted into DHT by the enzyme 5-alpha-reductase, which has two main forms. The type 2 form is mainly active in reproductive tissue, while type 1 also converts testosterone in the skin and liver (Avodart prescribing information). Finasteride is a type 2 inhibitor and dutasteride inhibits both. Both forms are present in hair follicles.

The measured effect on blood DHT differs. The finasteride 1 mg tablet reaches about 65% suppression within 24 hours (Propecia prescribing information). In a 24 week trial of 399 men with an enlarged prostate, dutasteride 0.5 mg lowered DHT by an average of 94.7%, compared with 70.8% for finasteride 5 mg (Clark et al., 2004). Two cautions apply when interpreting these results in the context of hair loss:

1. The finasteride arm used a 5 mg dose, five times the dose used in male pattern hair loss. Finasteride is used for other conditions (such as an enlarged prostate) at much higher doses than for hair loss, which is the dose that this study was evaluating.

2. Blood DHT is not hair growth: the finasteride product information states that the contribution of falls in scalp and blood DHT to the treatment effect has not been defined (Propecia prescribing information). Hair outcomes have to be measured directly.

What the Head to Head Trials Found

Three randomised trials compare the two medications in men with male pattern hair loss. All lasted 24 weeks.

In a 2014 trial of 917 men aged 20 to 50, dutasteride 0.5 mg gave higher hair count and width than finasteride 1 mg in the measured area, with similar number and severity of adverse events (Gubelin Harcha et al., 2014). Several of the authors worked for GlaxoSmithKline, a company that makes dutasteride.
In a 2017 trial of 90 men, total hair count rose from 223 to 246 per square centimetre with dutasteride 0.5 mg and from 227 to 231 with finasteride 1 mg. Participants knew which medicine they took, although the assessor did not (Shanshanwal and Dhurat, 2017).
In a 2025 pilot of 60 men, average terminal hair count rose by 7.7 (dutasteride twice weekly), 17.4 (three times weekly) and 12.8 (finasteride daily) hairs per square centimetre. The authors reported no significant difference in hair count between three times weekly dutasteride and daily finasteride, though 35% against 21% rated moderate to marked on photographs. Participants were not blinded (Sereepanpanich et al., 2025).

The larger studies report a bigger average change with dutasteride, while the smallest and most recent, using a less than daily schedule, did not find a significant difference in hair count. The answer can depend on dose, schedule, how hair is counted and how many men were studied.

What the Trials Cannot Show

Hair grows in cycles lasting months and years, and 24 weeks captures only the early response.
The trials report group averages. An average gap of a few hairs per square centimetre may or may not be noticeable to a particular person, and says nothing about who will have side effects.
Participants were mostly younger men with mild to moderate hair loss, so results may not apply to everyone.

There is also a gap in long term data. Finasteride product information describes trials in men aged 18 to 41 extended to five years, where a photographic panel rated hair growth as increased in 48% of men who continued, unchanged in 42% and reduced in 10%, against 6%, 19% and 75% on placebo. Only 290 men entered the fifth year, and the placebo group had shrunk to a few dozen after year two (Propecia prescribing information). No published dutasteride hair loss trial of comparable length has been conducted.

What the Pooled Analyses Add

A meta-analysis combines the results of multiple independent studies on the same question to produce an overall estimate of the effect or relationship being studied. A few meta analyses have been conducted to compare finasteride and dutasteride.

A 2019 meta analysis pooled three trials with 576 participants and found a higher mean change in total hair count with dutasteride at 24 weeks, with no significant difference in libido, erectile dysfunction or ejaculation disorders (Zhou et al., 2019).

A 2022 network meta analysis of 23 studies compared dutasteride, finasteride and minoxidil indirectly. At 24 weeks, dutasteride 0.5 mg had the largest increase in total hair count, 7.1 hairs per square centimetre more than finasteride 1 mg (95% confidence interval 5.1 to 9.3). At 48 weeks the leading results belonged to finasteride doses, and the authors concluded that more head to head trials are needed (Gupta et al., 2022). This particular meta analysis searched only a single database.

One 2025 review expressed its authors' view that topical minoxidil and oral finasteride are the well studied options, that oral dutasteride could be considered off label if those are ineffective, and that dutasteride may reduce sperm count and motility (Gupta and Talukder, 2025). That is one expert opinion rather than a guideline.

Side Effects Reported in the Trials

The listed side effects are similar, and the research does not show a clear difference in frequency. The figures below come from different populations and cannot be compared directly.

In finasteride 1 mg hair loss trials lasting 12 months (945 men on finasteride, 934 on placebo), decreased libido was reported by 1.8% and 1.3%, erectile dysfunction by 1.3% and 0.7%, and ejaculation disorder by 1.2% and 0.7%. Overall, 3.8% on finasteride and 2.1% on placebo reported one or more of these (Propecia prescribing information).
The dutasteride 0.5 mg figures come from men with an enlarged prostate, average age 66. In the first 6 months, impotence was reported by 4.7% on dutasteride and 1.7% on placebo, decreased libido by 3.0% and 1.4%, and ejaculation disorders by 1.4% and 0.5%. Rates were lower in later months (Avodart prescribing information). This study was conducted in an older population, which may increase the incidence of these symptoms.
A review of 17 randomised trials found more sexual dysfunction than placebo in men taking finasteride or dutasteride with an enlarged prostate, but no statistically significant difference in those taking these medications in hair loss trials (Liu et al., 2016). This is likely due to the lower dose used in hair loss.

Short trials cannot capture everything. The finasteride information lists reports of sexual dysfunction that continued after stopping, depression, suicidal thoughts and breast changes. The dutasteride information lists depressed mood, testicular pain and male breast cancer, and says sexual side effects may persist after stopping, with the role of the medicine unknown. Both say these reports come from a population of uncertain size, so frequency and cause cannot be reliably worked out (Propecia; Avodart). If you notice a change in mood or sexual function while taking any hair loss medication, tell your doctor immediately.

Both medicines also lower PSA (a prostate blood marker used to monitor for prostate cancer), by about 50% in the case of dutasteride. Anyone having a PSA test should tell their doctor about these DHT blocking medications in order to accurately interpret PSA results.

How Long Each Medicine Stays in the Body

Finasteride has a half life of about 5 to 6 hours in men aged 18 to 60 (Propecia prescribing information). Dutasteride is a different beast. It's terminal half life is about 5 weeks. Blood levels reach roughly 90% of steady state after 3 months and stay detectable for 4 to 6 months after the last dose, so the American label advises waiting 6 months after the last dose before donating blood (Avodart prescribing information). That slow build up and fade is why less than daily schedules have been studied, although the one pilot study above does not establish an ideal schedule.

The long half life also bears on fertility and pregnancy planning. In a trial of healthy men, total sperm count fell after 26 weeks on both finasteride 5 mg (a higher dose than that used for hair loss) and dutasteride 0.5 mg and sperm motility fell by 6 to 12% (Amory et al., 2007). The dutasteride label notes the effect on total sperm count had not reversed at 24 weeks of follow up, but that values stayed within the normal range, and that the significance for an individual's fertility is not known. Both labels advise women who are or may be pregnant not to handle the medicine (crushed or broken tablets for finasteride, capsules for dutasteride). If you are planning a family, discuss timing with your doctor before you start, change or stop anything. If you'd like to read more about family planning on DHT blocking medications, you can do so here: Family Planning and Hair Medications.

Where Each Medicine Stands in Australia

Finasteride 1 mg tablets are Schedule 4 prescription medicines registered for male pattern hair loss in men aged 18 and over. Product information states efficacy has not been demonstrated in men over 41. Dutasteride 0.5 mg capsules are also Schedule 4, but the registered use is for symptomatic benign prostatic hyperplasia (prostate enlargement), and the Australian listing does not mention hair loss. Using dutasteride for hair loss is therefore off label. Topical finasteride is also off label for hair loss.

Off label does not mean illegal. The Therapeutic Goods Administration (TGA) explains that off label use is a clinical decision made at the discretion of the prescriber, who is responsible for obtaining informed consent, and that no TGA exemption or authorisation is generally required (TGA, 2024).

Other Things Worth Weighing

The decision does not have to come down to these two. Some men choose a topical treatment such as minoxidil, which works through a different pathway and does not change DHT. Our article on pills versus sprays explains oral and topical options, and our overview of hair loss treatments covers the wider range, including hair transplants for more advanced loss. Doing nothing is also a legitimate choice. Male pattern hair loss is gradual and not harmful to health, and some men decide treatment is not worth the cost, the daily routine or the risk of side effects.

If you start any treatment, expectations matter. Results take months, hair can shed early on, and the effect depends on consistency and continuing use. Our guide on what to expect when starting hair loss medication covers the usual timeline, and the Norwood scale explains how the stage of hair loss is described.

When to See a Doctor

Your hair loss is sudden or patchy, or comes with scalp pain, redness or scarring, because these are not typical of male pattern hair loss.
You notice low mood, anxiety, changes in sexual function or breast changes while taking any hair loss medication.
You are planning a pregnancy with a partner, or thinking about donating blood.
You take other medicines, have a health condition, or are due for a PSA test.