Finasteride is often the most widely discussed treatment for male pattern hair loss. But dutasteride works in a similar way but it’s not as commonly used or widely available. In this guide, we’ll break down the key differences between the two, explain why finasteride is usually the first choice, and look at the situations where dutasteride might actually be a suitable alternative, as well as when it’s best avoided.
What’s the difference between Finasteride and Dutasteride?
Finasteride and dutasteride both help treat male pattern hair loss by blocking the enzyme 5αreductase (5AR), which is responsible for converting testosterone into DHT - the hormone that shrinks hair follicles and triggers thinning. By reducing DHT levels in the body, both medications slow shedding and encourage regrowth.
The key difference is how thoroughly it blocks this enzyme. Finasteride blocks only type-II, while dutasteride is a dual 5AR inhibitor, meaning it blocks both type-I and type-II 5α-reductase. Because of that, dutasteride lowers DHT levels more dramatically than finasteride: oral finasteride (5mg) tends to lower levels by about 70%, oral dutasteride 0.5mg reduces them by more than 90%.
Is dutasteride better at treating hair loss than finasteride?
Research so far shows that dutasteride may be better at stopping hair loss and achieving regrowth than finasteride, but with one key caveat: it’s not as extensively researched as finasteride.
Generally, across the studies which have compared oral dutasteride (0.5mg/day) to oral finasteride (1mg/day) as treatments for men with androgenetic alopecia, dutasteride is superior in improving hair outcomes like average hair count and hair thickness.
Furthermore, the side effect profile of finasteride and dutasteride are very similar. This makes sense, considering how they tackle hair loss through a very similar pathway. The most commonly reported side effects in both medications are sexual in nature, though they remain rare.
A 2024 review of three randomised controlled trials (RCTs) found consistent advantages for dutasteride in terms of total hair count, photographic assessments, and patient self ratings, without any meaningful differences in rates of issues like reduced libido or erectile dysfunction.
If dutasteride is more effective than finasteride, why isn’t it licensed?
Medications need to undergo high-quality Phase III trials and long-term post-marketing safety monitoring to receive a license in the UK. Finasteride 1mg has undergone all the steps required, where as dutasteride has not gone through the same approval process pathway (for hair loss).
One reason for this is the half-life of dutasteride is much longer than finasteride: approximately 5 weeks compared to 5-6 hours. This means that it takes dutasteride 5 to 6 months to completely clear from the body, where as finasteride will be out of your system after just a few days. For this reason, further phase-III trials have not been conducted in the UK due to safety concerns that side effects may last a long time.
What does ‘licensed’ and ‘off-label’ mean?
Both finasteride and dutasteride are licensed in the UK as a treatment for benign prostate hyperplasia (enlarged prostate), but only finasteride 1mg is licensed in the UK for hair loss.
When a doctor prescribes dutasteride for hair loss, they’re prescribing it off-label, meaning it’s being used for a condition outside the one specified on the licence. Off-label prescribing is a standard, safe, and widely accepted medical practice when good evidence supports the treatment.
The same applies to different formats or concentrations of finasteride. For example, topical versions of finasteride or dutasteride, like sprays, are considered unlicensed. However, spray versions containing these active ingredients are regularly prescribed for hair loss, as they have a lower chance of causing systemic side effects because much less of the medication is absorbed into the bloodstream.
Why dutasteride spray might be best
A 2025 Phase-II study examined three concentrations of dutasteride spray (0.01%, 0.02% and 0.05%) and compared them to oral finasteride 1 mg. Results improved as the dutasteride concentration increased, and the highest strength, 0.05%, actually outperformed finasteride in total hair count, global photographic assessments and patient reported improvement after 24 weeks.
These findings are promising, especially since finasteride has long been considered the gold standard. Still, this was an early stage trial, and dutasteride hasn’t built up the same depth of evidence or years of real world use that finasteride has.
Who is a good match?
Men who haven’t seen enough improvement with finasteride may find dutasteride a better fit, simply because it suppresses DHT more completely. It’s often considered a next step treatment for those who respond only partially to finasteride, or whose hair continues to thin despite using finasteride consistently.
Who isn't a good match?
Dutasteride isn’t suitable for everyone:
- If you’re trying to conceive soon: Dutasteride can cause changes in semen. At Sons, we recommend stopping it around 90 days before trying for a baby and avoiding unprotected sex with a pregnant partner during the first trimester, just as a precaution. The same advice applies to finasteride too.
- If you’re a woman or a child: Dutasteride isn’t recommended for women (especially those who are pregnant or could become pregnant) or for anyone under 18.
Finasteride is a well-studied option with decades of data behind it, which is why it’s regularly favoured by prescribers. For most men, it works as intended and there is no need to look further afield. However, every man is different, and finasteride may not work for everybody. In that case, dutasteride may be a next step in treatment.
If you think a different treatment option might be a better fit for you, speak to one of our knowledgeable Aftercare Advisors for advice and recommendations (contact details below).
Source List:
• Ding, Y., Wang, C., Bi, L., Du, Y., Lu, C., Zhao, M., & Fan, W. (2024). Dutasteride for the treatment of androgenetic alopecia: An updated review. Dermatology, 240(5–6), 833–843. https://doi.org/10.1159/000541395
• Al-Horani RA, Patel P. Dutasteride. [Updated 2024 Mar 20]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2025 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK603726/
• Almudimeegh A, AlMutairi H, AlTassan F, AlQuraishi Y, Nagshabandi KN. Comparison between dutasteride and finasteride in hair regrowth and reversal of miniaturization in male and female androgenetic alopecia: a systematic review. Dermatol Reports. 2024 Apr 12;16(4):9909. doi: 10.4081/dr.2024.9909. PMID: 39749123; PMCID: PMC11694415.
• Zhou Z, Song S, Gao Z, Wu J, Ma J, Cui Y. 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 Feb 20;14:399-406. doi: 10.2147/CIA.S192435. PMID: 30863034; PMCID: PMC6388756.
• Kaufman, K. D., Olsen, E. A., Whiting, D., Savin, R., DeVillez, R., Bergfeld, W., Price, V. H., Van Neste, D., Roberts, J. L., Hordinsky, M., Shapiro, J., Binkowitz, B., & Gormley, G. J. (1998). Finasteride in the treatment of men with androgenetic alopecia. Journal of the American Academy of Dermatology, 39(4), 578–589. https://doi.org/10.1016/S0190-9622(98)70007-6
• Choi GS, Sim WY, Kang H, Huh CH, Lee YW, Shantakumar S, Ho YF, Oh EJ, Duh MS, Cheng WY, Bobbili P, Thompson-Leduc P, Ong G. 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 Oct;34(5):349-359. doi: 10.5021/ad.22.027. PMID: 36198626; PMCID: PMC9561294.
• Aronson JK, Ferner RE. Unlicensed and off-label uses of medicines: definitions and clarification of terminology. Br J Clin Pharmacol. 2017 Dec;83(12):2615-2625. doi: 10.1111/bcp.13394. Epub 2017 Sep 26. PMID: 28779556; PMCID: PMC5698582.
• Panuganti VK, Kumar Madala P, Ramalingayya Grandhi V, Varma Alluri C, Mohammad J, Rao Kssvv S, Reddy Dundigalla M. A Randomized, Double-Blind, Placebo and Active Controlled Phase II Study to Evaluate the Safety and Efficacy of Novel Dutasteride Topical Solution (0.01%, 0.02%, and 0.05% w/v) in Male Subjects With Androgenetic Alopecia. Cureus. 2025 Aug 3;17(8):e89309. doi: 10.7759/cureus.89309. PMID: 40909044; PMCID: PMC12405733.
All of our blog articles are reviewed by our Medical Director before publication.
