Dutasteride vs Finasteride: What the Trials Compared

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Short answer: On dutasteride vs finasteride, the Propecia (finasteride 1 mg) prescribing information lists male pattern hair loss as its indication, while the Avodart (dutasteride) prescribing information lists only an enlarged prostate, so dutasteride’s use for hair loss in the US is off-label (Propecia prescribing information; Avodart prescribing information). In 24-week head-to-head trials, the authors reported larger gains in hair count with dutasteride 0.5 mg than with finasteride 1 mg and similar side-effect rates, and three of the nine authors of the largest trial worked for GSK (Gubelin Harcha et al., 2014). The prescribing information lists a half-life of about 5 weeks for dutasteride and about 5 to 6 hours for finasteride.

PrescribedRX does not offer dutasteride. This page sets out what the prescribing information and comparison trials report, including who funded them. For more on dutasteride alone, see dutasteride side effects and results in detail.

What is the difference between dutasteride and finasteride?

Both drugs are 5-alpha reductase inhibitors. That enzyme converts testosterone into dihydrotestosterone (DHT), and it comes in two forms, type 1 and type 2. The Avodart prescribing information describes dutasteride as an inhibitor of both the type 1 and type 2 forms (Avodart prescribing information). The Propecia prescribing information describes finasteride as a Type II inhibitor (Propecia prescribing information).

In a 24-week trial of 399 men with enlarged prostates, mean DHT fell by 94.7% with dutasteride 0.5 mg and by 70.8% with finasteride 5 mg (P < 0.001). The first author worked for GlaxoSmithKline (GSK) Research and Development (Clark et al., 2004). Note that 5 mg is the prostate dose of finasteride, not the 1 mg hair-loss dose.

Which one is indicated for hair loss?

Only finasteride. The Propecia prescribing information says it is indicated for male pattern hair loss “in MEN ONLY,” and that efficacy in bitemporal recession (the temples) has not been established (Propecia prescribing information). The Avodart prescribing information covers symptomatic benign prostatic hyperplasia (BPH) in men with an enlarged prostate and does not mention hair loss (Avodart prescribing information).

Outside the US, Japan’s drug regulator reviewed dutasteride for male androgenetic alopecia in 2015, under the brand name Zagallo from GSK’s Japanese company (PMDA review report). A 2022 Korean paper states that it was approved for hair loss in South Korea in 2009 (Choi et al., 2022).

What each prescribing document lists, side by side:

	Dutasteride (Avodart)	Finasteride (Propecia)
Enzyme forms blocked	Type 1 and type 2	Type II
Listed use (US)	Symptomatic BPH with an enlarged prostate	Male pattern hair loss, men only
Listed dose	0.5 mg (for BPH)	1 mg (for hair loss)
Half-life	About 5 weeks at steady state	About 5 to 6 hours (ages 18 to 60); 8 hours over 70
Still detectable after stopping	Up to 4 to 6 months	Not stated
Blood donation wait after last dose	6 months (prescribing information and Red Cross)	1 month (Red Cross)
Effect on PSA	Lowers PSA by about 50% within 3 to 6 months	Lowers PSA
Pregnancy	Women who are or may be pregnant should not handle the capsules	Women who are or may be pregnant should not handle crushed or broken tablets

Sources: Avodart prescribing information (rev. 10/2023), Propecia prescribing information (rev. 11/2023), American Red Cross eligibility criteria.

What did the head-to-head trials find?

The studies below compared the two drugs directly. The table gives each one’s size, length and doses. GSK’s Japanese company sought approval of dutasteride for hair loss in Japan (PMDA), so the table also notes GSK involvement where the published record shows it.

Study	Men and length	Doses compared	What the authors reported	Funding or GSK ties
Olsen 2006, randomized	416 men, 24 weeks	Dutasteride 0.05, 0.1, 0.5 or 2.5 mg vs finasteride 5 mg vs placebo	Dutasteride 2.5 mg superior to finasteride 5 mg at 12 and 24 weeks	Not stated in the abstract
Gubelin Harcha 2014, randomized	917 men, 24 weeks	Dutasteride 0.02, 0.1 or 0.5 mg vs finasteride 1 mg vs placebo	Dutasteride 0.5 mg ahead of finasteride on hair count, hair width and frontal photos; side effects similar	3 of 9 authors were GSK employees
Shanshanwal 2017, randomized, open-label	90 men, 24 weeks	Dutasteride 0.5 mg vs finasteride 1 mg	Larger rise in total hair count with dutasteride; similar side effects	Financial support: “Nil”
Zhou 2019, meta-analysis	576 men in 3 trials, 24 weeks	Dutasteride vs finasteride	Greater total hair count with dutasteride; no significant difference in sexual side effects	No specific grant; no conflicts reported
Gupta 2022, network meta-analysis	23 studies	Minoxidil, dutasteride and finasteride at various doses	At 24 weeks, dutasteride 0.5 mg ahead of finasteride 1 mg on total hair count	No conflicts reported
Choi 2022, chart review	600 Korean men, observational	Dutasteride vs finasteride in clinic practice	Greater improvement in hair loss grade with dutasteride; side effects 7.6% vs 10.5%	4 authors GSK employees; consulting firm funded for the study

Olsen 2006: the first comparison used prostate doses

Olsen and colleagues randomized 416 men aged 21 to 45. The authors reported dose-dependent hair count gains with dutasteride, and the 2.5 mg dose was superior to finasteride at 12 and 24 weeks (Olsen et al., 2006). Both doses in that comparison differ from the US prescribing doses: dutasteride 2.5 mg is five times the Avodart dose, and finasteride 5 mg is five times the Propecia dose. The abstract does not state who funded it.

Gubelin Harcha 2014: the largest trial, at the US prescribing doses

This trial randomized 917 men aged 20 to 50. At 24 weeks, the authors reported that dutasteride 0.5 mg significantly increased hair count (P = .003) and hair width (P = .004) and improved a panel’s rating of frontal photos (P = .002) compared with finasteride 1 mg. The number and severity of adverse events were similar across groups (Gubelin Harcha et al., 2014). Three of the nine authors list GlaxoSmithKline Research and Development as their affiliation.

Shanshanwal 2017: a smaller trial with no reported funding

In 90 men aged 18 to 40, total hair count per square centimeter went from 223 to 246 with dutasteride 0.5 mg and from 227 to 231 with finasteride 1 mg over 24 weeks. The authors reported a similar side-effect profile, with sexual dysfunction the most common (Shanshanwal and Dhurat, 2017). The authors list the short length, small size and open-label design as limits. The journal lists the study’s financial support as “Nil.”

The pooled analyses

Zhou and colleagues pooled the three trials above (576 men). They reported a mean difference of 28.57 in total hair count in favor of dutasteride (95% CI 18.75 to 38.39). Odds ratios for altered libido (1.12), erectile dysfunction (1.18) and ejaculation disorders (0.75) were not statistically significant. The authors write that they “could not infer the long-term efficacy and tolerance” of either drug (Zhou et al., 2019).

A 2022 network meta-analysis of 23 studies reported that at 24 weeks, dutasteride 0.5 mg a day was ahead of finasteride 1 mg a day on total hair count by a mean of 7.1 hairs per square centimeter (95% CI 5.1 to 9.3) (Gupta et al., 2022).

Choi 2022: longer, but not randomized

A Korean chart review of 600 men reported greater improvement in hair loss classification with dutasteride (adjusted incidence rate ratio 2.06). Adverse events were recorded in 7.6% of dutasteride users and 10.5% of finasteride users (p = 0.201). Four authors were GSK employees, and the consulting firm that ran the analysis received funding for the study (Choi et al., 2022). Dutasteride users were older and had more severe hair loss at the start.

The limits of this evidence

Every randomized comparison on this page lasted 24 weeks, and the longest data come from a chart review. None of these trials tested what happens when men stop dutasteride.

Finasteride vs dutasteride: how do the side effects compare?

In the hair-loss trials, the authors reported similar side-effect rates for the two drugs (Gubelin Harcha et al., 2014; Zhou et al., 2019). In EPICS, a 12-month trial of 1,630 men aged 50 and older with BPH, dutasteride 0.5 mg and finasteride 5 mg produced “a similar percentage of adverse events” (Nickel et al., 2011).

Each prescribing document has its own table. They come from different trials, populations and doses, so they are not a head-to-head comparison:

Side effect	Propecia 1 mg vs placebo, year 1 (hair-loss trials)	Avodart 0.5 mg vs placebo, months 0 to 6 (BPH trials)
Decreased libido	1.8% vs 1.3%	3.0% vs 1.4%
Erectile dysfunction / impotence	1.3% vs 0.7%	4.7% vs 1.7%
Ejaculation disorder	1.2% vs 0.7%	1.4% vs 0.5%

Sources: Propecia prescribing information, Table 1 (men with male pattern hair loss); Avodart prescribing information (older men with enlarged prostates). In the Avodart table, these rates were close to placebo by months 19 to 24.

The Avodart prescribing information adds that these sexual side effects “may persist after treatment discontinuation” and that “the role of dutasteride in this persistence is unknown.” Both prescribing documents say the drugs lower PSA, a blood test used to screen for prostate cancer, and that a confirmed rise in PSA while on treatment should be evaluated (Avodart prescribing information; Propecia prescribing information).

How long does each drug stay in your body?

The Avodart prescribing information gives a terminal half-life of about 5 weeks at steady state, with blood levels still detectable (above 0.1 ng/mL) for up to 4 to 6 months after stopping (Avodart prescribing information). The Propecia prescribing information gives about 5 to 6 hours in men aged 18 to 60 and 8 hours in men over 70 (Propecia prescribing information).

Can you donate blood on dutasteride or finasteride?

Both drugs have a waiting period. The Avodart prescribing information says men “should not donate blood until at least 6 months have passed following their last dose,” to keep the drug from reaching a pregnant transfusion recipient (Avodart prescribing information). The Propecia prescribing information has no blood donation section. The American Red Cross lists a 1-month wait after the last dose of Propecia or Proscar (finasteride) and a 6-month wait after Avodart or Jalyn (dutasteride) (American Red Cross).

What happens when you stop?

For finasteride, the Propecia prescribing information says “withdrawal of treatment leads to reversal of effect within 12 months,” and that daily use “for three months or more is necessary before benefit is observed” (Propecia prescribing information). For dutasteride, the hair-loss trials on this page did not test stopping, so there is no figure to report. More on finasteride is in our guide to finasteride for hair loss.

When should you talk to a doctor?

Talk to a licensed provider about any of the following. Each comes from the prescribing information cited above.

• Sexual side effects that persist (the Avodart prescribing information says they may persist after stopping).
• Breast tenderness, enlargement or a lump (the Avodart prescribing information table includes breast disorders).
• An upcoming PSA test or prostate biopsy (both prescribing documents say these drugs lower PSA).
• A partner who is or may be pregnant has handled a crushed or broken finasteride tablet or a dutasteride capsule (both prescribing documents warn against this).

Frequently asked questions

Is dutasteride stronger than finasteride?

Clark 2004 reported a 94.7% drop in blood DHT with dutasteride 0.5 mg versus 70.8% with finasteride 5 mg. In 24-week hair-loss trials, authors reported larger hair count gains with dutasteride 0.5 mg than finasteride 1 mg. No randomized comparison here ran past 24 weeks.

Is dutasteride indicated for hair loss in the US?

No. In the US, the Avodart prescribing information lists symptomatic BPH in men with an enlarged prostate, so hair loss use is off-label. The Propecia (finasteride 1 mg) prescribing information lists male pattern hair loss.

Does dutasteride have more side effects than finasteride?

In the head-to-head hair-loss trials and the Zhou 2019 meta-analysis, the authors reported no significant difference in sexual side effects. The prescribing documents give dutasteride a half-life of about 5 weeks versus hours for finasteride, and the Avodart prescribing information sets a 6-month blood donation wait.

Can you switch from finasteride to dutasteride?

That is a decision for a licensed provider who knows your history. None of the trials here tested switching. For the wider picture, see hair loss treatments ranked by evidence and minoxidil vs finasteride.

Where does PrescribedRX fit?

PrescribedRX does not offer dutasteride. The hair loss treatment offered through PrescribedRX is Hair We Grow, listed on its product page as finasteride plus minoxidil in one daily capsule. It is compounded and does not contain dutasteride. Compounded medications are prepared by licensed pharmacies and are not FDA-approved. A licensed provider decides whether it is appropriate for you.

A licensed provider reviews your online intake, typically within 48 hours, and a prescription is issued only if a licensed provider determines treatment is appropriate. Your provider sets the dose. Plans are self-pay, and availability varies by state.

Prices as shown on prescribedrx.com in October 2026 (see what every PrescribedRX treatment costs):

Plan	Price as displayed
Hair We Grow, 3 months	3 month plan $220 · $73/mo · Billed every 3 months. Cancel anytime.
Hair We Grow, monthly	Monthly plan $90 a month

Questions about hair loss treatment? Talk to a licensed provider

A licensed provider can review your history and the options available in your state, and a prescription is issued only if a licensed provider determines treatment is appropriate. Explore prescription hair loss treatment online.

Hair We Grow (finasteride and minoxidil in one daily capsule; compounded): 3 month plan $220 · $73/mo · Billed every 3 months. Cancel anytime.

Related reading: finasteride and minoxidil together

Sources

1. DailyMed, National Library of Medicine. AVODART (dutasteride) capsules prescribing information (rev. 10/2023). dailymed.nlm.nih.gov. Accessed Oct 2026.
2. DailyMed, National Library of Medicine. PROPECIA (finasteride) tablets prescribing information (rev. 11/2023). dailymed.nlm.nih.gov. Accessed Oct 2026.
3. Olsen EA, et al. The importance of dual 5alpha-reductase inhibition in the treatment of male pattern hair loss: results of a randomized placebo-controlled study of dutasteride versus finasteride. J Am Acad Dermatol. 2006;55(6):1014-1023. PubMed. Accessed Oct 2026.
4. Gubelin Harcha W, et al. 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):489-498. PubMed. Accessed Oct 2026.
5. Shanshanwal SJ, Dhurat RS. Superiority of dutasteride over finasteride in hair regrowth and reversal of miniaturization in men with androgenetic alopecia: a randomized controlled open-label, evaluator-blinded study. Indian J Dermatol Venereol Leprol. 2017;83(1):47-54. PubMed. Accessed Oct 2026.
6. Zhou Z, et al. The efficacy and safety of dutasteride compared with finasteride in treating men with androgenetic alopecia: a systematic review and meta-analysis. Clin Interv Aging. 2019;14:399-406. PMC. Accessed Oct 2026.
7. Gupta AK, et al. Relative efficacy of minoxidil and the 5-alpha reductase inhibitors in androgenetic alopecia treatment of male patients: a network meta-analysis. JAMA Dermatol. 2022;158(3):266-274. PubMed. Accessed Oct 2026.
8. Choi GS, et al. Long-term effectiveness and safety of dutasteride versus finasteride in patients with male androgenic alopecia in South Korea: a multicentre chart review study. Ann Dermatol. 2022;34(5):349-359. PMC. Accessed Oct 2026.
9. Clark RV, et al. Marked suppression of dihydrotestosterone in men with benign prostatic hyperplasia by dutasteride, a dual 5alpha-reductase inhibitor. J Clin Endocrinol Metab. 2004;89(5):2179-2184. PubMed. Accessed Oct 2026.
10. Nickel JC, et al. Comparison of dutasteride and finasteride for treating benign prostatic hyperplasia: the Enlarged Prostate International Comparator Study (EPICS). BJU Int. 2011;108(3):388-394. PubMed. Accessed Oct 2026.
11. American Red Cross. Eligibility criteria: alphabetical (medications). redcrossblood.org. Accessed Oct 2026.
12. Pharmaceuticals and Medical Devices Agency (Japan). Review Report: Zagallo (dutasteride) for androgenetic alopecia (2015). pmda.go.jp. Accessed Oct 2026.

This article is for general information. It is not medical advice and it is not a recommendation for any particular treatment. Whether a treatment is appropriate for you is a decision for a licensed clinician who has reviewed your health history and current medications.