What is Finasteride?
Finasteride is a popular prescription medication for treating male pattern baldness (androgenic alopecia). First approved by the U.S. FDA in 1997 as remedy for androgenic alopecia, it was initially produced by Merck & Co. and branded as Propecia, coming in the form of a 1mg once a day pill. Five years earlier Merck already had Finasteride approved as a treatment for enlarged prostate gland (benign prostatic hyperplasia, BPH). To treat BPH a daily dose of 5mg Finasteride is used, which Merck sells as Proscar. Nowadays, many generic versions are available for both Propecia (1mg) and Proscar (5mg).
As has been demonstrated in several long-term studies of up to 10 years, Finasteride successfully stops male pattern hair loss in about 85 percent of men. For some 65 percent of users it even triggers new hair to grow, i.e., new hair appears in previously bald hair follicles.
Finasteride is called a 5α-reductase inhibitor, because it works by blocking the production of dihydrotestosterone (DHT) in the scalp and prostate gland. It’s the DHT that damages hair follicles and in doing so causes balding and prostate enlargement. 5α-reductase is the enzyme that transforms testosterone into DHT. Once this enzyme is inhibited by Finasteride, DHT production drops by 70-80%.
What is Dutasteride?
Dutasteride also is a 5α-reductase inhibitor that functions very similar to Finasteride in its suppression of DHT and thus serves the same purpose of treating male pattern baldness and BPH. Dutasteride was FDA approved in 2001 as a medication for BPH. It is sold under the proprietary name Avodart (0.5mg capsules that are taken once a day) by GlaxoSmithKline and sometimes combined with tamsulosin as Duodart and Combodart. Generic alternatives are also widely sold.
However, Dutasteride so far hasn’t received FDA approval for treating baldness, even though it has been licensed for this use in several other countries. This means that Dutasteride in the United States can only be prescribed by doctors for BPH or other conditions stated on its label, but not for hair loss.
Which one is more effective for treating male pattern hair loss?
Both drugs do what they are supposed to do fairly well. The vast majority of men find that either medication typically stops their baldness problem within six months of use. Clinical studies, however, have indicated that Dutasteride’s inhibiting effect on DHT production is slightly more powerful than that of Finasteride.
Comparing a 5mg dosage of Finasteride with 0.5mg of Dutasteride taken by nearly 400 men, one study found that Dutasteride inhibited DHT production by 98.4 percent (+-1.2 percent) whereas Finasteride only reduced DHT production by 70.8 percent (+-18.3 percent). It’s not just that the absolute success rate of Dutasteride was higher, but its effect had a narrow range of plus or minus 1.2 percent. This means that the DHT reduction result was more or less the same for all men in the Dutasteride group. Meanwhile the range of Finasteride was a much broader plus or minus 18.3 percent, which means there is greater variability in the expected outcome.
Other studies that go beyond testosterone-DHT conversion and focus on the effect on hair growth found that Dutasteride tends to stimulate slightly more hair regrowth than Finasteride.
Research as to why Dutasteride produces somewhat better results than Finasteride is still ongoing, but one factor could be that Dutasteride remains in the body much longer than Finasteride. The body half-life of Dutasteride is about one month for men younger than 70, whereas Finasteride leaves the body within half a day’s time.
Finasteride and Dutasteride both require patience, as the first visible results on hair volume and quality appear only within about 4 months. There is no indication that Dutasteride acts notably faster than Finasteride.
Are the side effects different?
Both Finasteride and Dutasteride can have mild side effects that are similar in nature, given that both drugs come from the same family of 5α-reductase inhibitors. These side effects typically include dizziness, skin rashes, confusion, swollen limbs and breast tenderness. In rare cases there can be sexual side effects, such as decreased libido and erectile dysfunction.
Many men worry about these sexual side effects of Finasteride and Dutasteride and there is much discussion on the internet about this topic and which drug may have the least adverse effects. In reality, as a comparative study on over 1,600 men has shown, the overall risk is low and there is no significant difference between the two drugs.
In that study, 817 participants received 5mg of Finasteride and 813 men took 0.5mg of Dutasteride over the course of 12 months. General sexual side effects were noticed by only 11 percent of the Dutasteride users and 14 percent of the Finasteride group. Severe side effects were rarer yet. Only 1 percent of each group complained about ejaculatory disorder, and only about 5 percent noticed decreased libido.
Talk to your dermatologist to learn more about the side effects of Finasteride and Dutasteride.
Which drug is the right choice for you?
If you live in the United States, this question has a short answer: only Finasteride is an FDA-approved medication for treating male pattern hair loss. Beware that buying Dutasteride through online pharmacies that don’t require prescriptions is dangerous. These internet pharmacies operate illegally and don’t comply with U.S. pharmacy standards. There have been many reports of counterfeit or adulterated drugs, as well as fraud and identity theft.
Research on Dutasteride’s usefulness for male pattern baldness will continue and eventually at some point in the future the FDA may approve the drug for this use. Until then, Finasteride is your safe choice if you live in the United States.
It also is an effective choice, as many tests have shown. Remember: it stops baldness in 85 percent of men and regrows hair for some 65 percent of them. Moreover, in terms of side effects Finasteride is just as well tolerated as Dutasteride. There is little difference between the two drugs.
In the end, only your healthcare specialist and you yourself can judge which drug would be best for protecting your hair and stop baldness. Consult your doctor to figure out which drug would be the best treatment for you.
- Andriole, Gerald L, and Roger Kirby. “Safety and Tolerability of the Dual 5α-Reductase Inhibitor Dutasteride in the Treatment of Benign Prostatic Hyperplasia.” European Urology, vol. 44, no. 1, July 2003, pp. 82–88, www.sciencedirect.com/science/article/pii/S0302283803001982, https://doi.org/10.1016/s0302-2838(03)00198-2. Accessed 27 Nov. 2019.
- Olsen, Elise A., et al. “The Importance of Dual 5α-Reductase Inhibition in the Treatment of Male Pattern Hair Loss: Results of a Randomized Placebo-Controlled Study of Dutasteride versus Finasteride.” Journal of the American Academy of Dermatology, vol. 55, no. 6, Dec. 2006, pp. 1014–1023, www.sciencedirect.com/science/article/pii/S0190962206012874, https://doi.org/10.1016/j.jaad.2006.05.007. Accessed 26 Nov. 2019.
- Clark, Richard V., et al. “Marked Suppression of Dihydrotestosterone in Men with Benign Prostatic Hyperplasia by Dutasteride, a Dual 5α-Reductase Inhibitor.” The Journal of Clinical Endocrinology & Metabolism, vol. 89, no. 5, May 2004, pp. 2179–2184, academic.oup.com/jcem/article/89/5/2179/2844345, 10.1210/jc.2003-030330. Accessed 26 Nov. 2019.
- Nickel, J Curtis. “Comparison of Clinical Trials with Finasteride and Dutasteride.” Reviews in Urology, vol. 6 Suppl 9, no. Suppl 9, 2004, pp. S31-9, www.ncbi.nlm.nih.gov/pmc/articles/PMC1472914/. Accessed 27 Nov. 2019.