Dutasteride vs Finasteride for Men's Hair Loss: What the Head-to-Head Trials Show, and the Safety Trade-Offs
In 24-week head-to-head trials, dutasteride 0.5 mg grew more hair than finasteride 1 mg. But dutasteride is approved in the US only for an enlarged prostate, stays in the body for months, and carries the same class warnings, so the extra hair comes with real trade-offs.
By Kymata Health Editorial Published Last checked
This guide
Men's Hair Loss- Question
- Is dutasteride better than finasteride for male pattern hair loss, and is it safe?
- Sources
- 5 cited
- Quick answers
- 3 questions
- Clinician review
- None; sources cited inline
Key takeaways
5 points- In a 917-man trial, dutasteride 0.5 mg increased hair count and width more than finasteride 1 mg at 24 weeks; the trial was sponsored by GlaxoSmithKline, dutasteride's maker, and three of its nine authors worked there2.
- A 2022 network meta-analysis ranked dutasteride 0.5 mg first for total hair count at 24 weeks, 7.1 hairs/cm² ahead of finasteride 1 mg4.
- In the US, dutasteride (Avodart) is approved only for benign prostatic hyperplasia (BPH), so using it for hair loss is off-label5.
- Its half-life is about 5 weeks and it stays detectable for 4 to 6 months after the last dose; men should not donate blood until 6 months after stopping5.
- Its label lists the same kinds of sexual side effects as finasteride, notes they may persist after stopping, and adds depressed mood from post-marketing reports5.
How the two drugs differ
Both drugs block 5-alpha-reductase, the enzyme that turns testosterone into DHT, the hormone that shrinks follicles in pattern hair loss. Finasteride blocks the type II form only; dutasteride blocks types I and II12. In the 2006 dose-ranging trial, scalp and blood DHT fell further as the dutasteride dose rose1.
Their US status is different. Finasteride 1 mg (Propecia) is FDA-approved for male pattern hair loss (our finasteride guide). Dutasteride 0.5 mg (Avodart) is approved for symptomatic BPH in men with an enlarged prostate, alone or with tamsulosin5. A US prescription of dutasteride for hair loss is off-label.
What the head-to-head trials show
Three randomized trials tested dutasteride for hair loss, and all three were funded by its maker, GlaxoSmithKline123. All lasted 24 weeks to 6 months, so they cannot say how the drugs compare over years:
- Olsen 2006: 416 men aged 21 to 45 took dutasteride (0.05, 0.1, 0.5 or 2.5 mg), finasteride 5 mg or placebo for 24 weeks. Hair count rose with the dutasteride dose, and 2.5 mg beat finasteride 5 mg at 12 and 24 weeks1. Four of the eight named authors were GlaxoSmithKline employees1.
- Gubelin Harcha 2014: 917 men aged 20 to 50 took dutasteride (0.02, 0.1 or 0.5 mg), finasteride 1 mg or placebo for 24 weeks. Dutasteride 0.5 mg increased hair count and width and improved panel-rated frontal photos more than finasteride 1 mg, with similar numbers and severity of adverse events across groups2. GlaxoSmithKline sponsored the trial and paid for medical writing support, and three of the nine authors worked for GlaxoSmithKline Research & Development2.
- Eun 2010: 153 men aged 18 to 49, in a GlaxoSmithKline-supported trial led from Seoul National University, took dutasteride 0.5 mg or placebo for 6 months. Hair count rose by 12.2 per cm² on dutasteride vs 4.7 per cm² on placebo, with no major difference in adverse events3.
- Gupta 2022, a network meta-analysis of 23 studies: dutasteride 0.5 mg gave the largest gain in total hair count at 24 weeks, 7.1 hairs/cm² more than finasteride 1 mg (95% CI 5.1 to 9.3). At 48 weeks, finasteride led both end points (5 mg for total hair count, 1 mg for terminal hair count), not dutasteride4. The authors reported no conflicts of interest4.
Safety: what the Avodart label says
The label's side-effect data come from more than 4,300 men with BPH aged 47 to 94 (mean 66), not young men with hair loss5. In the first 6 months, impotence was reported by 4.7% on dutasteride vs 1.7% on placebo, decreased libido by 3.0% vs 1.4%, and ejaculation disorders by 1.4% vs 0.5%; rates fell in later months5. The label says these sexual side effects may persist after stopping, and that dutasteride's role in that persistence is unknown5. Post-marketing reports add depressed mood, male breast cancer, testicular pain and swelling, and allergic reactions including angioedema5.
Dutasteride lingers. Its half-life is about 5 weeks, and blood levels stay detectable for 4 to 6 months after the last dose5. Men taking it should not donate blood until at least 6 months after their last dose, so it cannot reach a pregnant transfusion recipient5.
It roughly halves PSA within 3 to 6 months; the label tells clinicians to set a new PSA baseline after 3 months and to double an isolated PSA value when comparing it with normal ranges5. Like finasteride, it may raise the risk of high-grade prostate cancer: in the 4-year REDUCE trial of men 50 to 75, Gleason 8 to 10 cancers occurred in 1.0% on dutasteride vs 0.5% on placebo5. In healthy men it also reduced total sperm count, semen volume and sperm movement; the drop in total sperm count had not reversed 24 weeks after stopping, and the effect on an individual man's fertility is unknown5.
Who should avoid it, and when to see a clinician
Dutasteride is contraindicated in pregnancy, and women who are or may be pregnant should not handle the capsules, because dutasteride can be absorbed through the skin and could expose a male fetus5. The label says it is not indicated for women or for children5.
Men planning a child, men with a history of depression or sexual dysfunction, and anyone who wants a quick exit if side effects appear should weigh its months-long washout before choosing it over finasteride5. Tell anyone checking your PSA that you take it5. See a clinician promptly for mood changes, breast lumps or nipple discharge, or testicular pain, and get help right away for thoughts of self-harm (in the US, call or text 988).
A reasonable order of steps: start with an FDA-approved option (finasteride, or minoxidil) and give it the months its label says it needs; discuss dutasteride with a dermatologist only if that has not worked and you accept off-label use. You can compare clinics on our hair loss treatment online page.
Quick answers
Questions
3 answersIs dutasteride stronger than finasteride for hair?
In 24-week trials it grew more hair than finasteride 1 mg24. Longer head-to-head data are lacking.
Is dutasteride FDA-approved for hair loss?
No. In the US it is approved for an enlarged prostate (BPH), so hair-loss use is off-label5.
How long does dutasteride stay in your body?
Its half-life is about 5 weeks, and it stays detectable for 4 to 6 months after the last dose5.
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References
Every study and document cited in this guide, numbered as in the text.
Sources
5 sources- 1The 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. PMID 17110217
- 2A 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. PMID 24411083
- 3Efficacy, safety, and tolerability of dutasteride 0.5 mg once daily in male patients with male pattern hair loss: a randomized, double-blind, placebo-controlled, phase III study. J Am Acad Dermatol, 2010. PMID 20605255
- 4Relative Efficacy of Minoxidil and the 5-α Reductase Inhibitors in Androgenetic Alopecia Treatment of Male Patients: A Network Meta-analysis. JAMA Dermatol, 2022. PMID 35107565
- 5AVODART (dutasteride) soft gelatin capsules: prescribing information (revised 2020). U.S. Food and Drug Administration, 2020.
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