In one of the first single-blind, placebo-controlled clinical trials of topical finasteride, Mazarella et al.¹ (1997) published a study of 52 subjects ranging from 19 to 28 years of age. The patients were treated with topical finasteride 0.005% vs placebo for 16 months. Here were the results.

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• There was a significant reduction in the rate of hair loss after 6 months of treatment.
• There was slight to marked reduction of the balding areas in the patients using the topical finasteride.
• 73% of the patients using the topical finasteride reported moderate effectiveness.

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In another double blind, randomized clinical trial study of 45 male patients, Hajheydari et al.² (2009) compared oral finasteride 1mg vs topical finasteride 1% for a total of 6 months.

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• Both the oral finasteride 1mg and the topical finasteride 1% showed statistically significant increase in total and terminal hair count after 4 months.
• There was no significant difference between the two groups in hair thickness, total hair counts and the size of bald area.
• Authors concluded that “the therapeutic effects of both finasteride gel and finasteride tablet were relatively similar to each other.”

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In a prospective pilot study conducted in 15 patients for 9 months by Rafi and Katz³ (2011), patients applied a topical solution called NuH Hair, which is a novel topical combination of finasteride, dutasteride, and minoxidil, with the option to add oral finasteride, minoxidil and/or ketoconazole shampoo for 9 months.

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• Significant growth was demonstrated after 3 months of use of the topical solution.
• In those patients who utilized the NuH Hair along with either Rogaine foam, Propecia, and ketoconazole shampoo saw significant growth was achieved in as little as 30 days.

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In a randomized clinical study by Tanglertsampan C.⁴  (2012), 33 male patients ranging between 27 to 49 years old were enrolled to compare the efficacy and safety of a 24 weeks application of minoxidil 3% lotion versus minoxidil 3% combined with 0.1% finasteride lotion.

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• Hair count increased in both groups but was only significant in the finasteride + minoxidil group.
• This study showed that finasteride combined with minoxidil is superior to minoxidil alone by itself.
• Finasteride combined with minoxidil showed significantly higher efficacy by global photographic assessment compared to the minoxidil group.

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Caserini et al. conducted two pharmacokinetic studies on topical finasteride. In a randomized clinical study of 23 males, Caserini et al.⁵ (2014) compared topical finasteride 0.25% twice daily vs oral finasteride 1mg once daily for 7 days. They measured DHT and testosterone levels in the serum (systemic DHT levels).

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• Similar reduction in serum DHT was observed by the use of topical 0.25% finasteride twice daily  (68-75% ) and oral finasteride 1mg (62-72%).
• No relevant changes occurred for serum testosterone.

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In another randomized clinical trial, Caserini et al.⁶ (2015) did another study involving 50 male patients studying DHT in both the serum and the scalp.

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• Scalp DHT was reduced by 71% with the use of 1ml topical finasteride 0.25% once daily application vs 51% reduction in scalp DHT with the use of oral finasteride 1mg once daily.
• Interestingly, once a day application of the 1ml topical finasteride 0.25% lead to a higher reduction of scalp DHT (71%) vs twice a day application of 1ml topical finasteride 0.25% (47%).
• Serum DHT decreased by 60 – 70% with the use of both 1ml topical finasteride and 1mg of oral finasteride.
• This pharmacokinetic study confirmed that topical finasteride 0.25% (1ml application twice daily) and oral finasteride 1mg (once daily) both have similar reduction in scalp (47-51%) and serum DHT levels (74-76%). No changes in testosterone were observed.

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In a retrospective assessment and prospective crossover cohort study of 50 male between 20 to 40 years old by Chandrashekar et al.⁷ (2017), all 50 patients used minoxidil 5% and oral 1mg finasteride for 2 years.They then stopped and their treatment differed.

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• 45 of the patients that stopped the above treatment immediately started topical minoxidil 5% + finasteride 0.1% treatment for 1 year.
• Results showed that 84.4% of these patients maintained good hair density while on the topical combination.
• 5 of the patients stopped all treatments for 8-12 months and then started the topical minoxidil 5% + finasteride 0.1% for 1 year.
• Results showed that 80% of these patients maintained good hair density.

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The studies⁸ above demonstrate that topical finasteride has clinically proven, evidence-based, scientific data to show its efficacy in growing hair. Firstly, pharmacokinetic studies suggest that topical finasteride results in a similar reduction in scalp DHT as oral finasteride. Studies also suggest that topical finasteride causes a statistically significant increase in total and terminal hair count. Additionally, when topical finasteride was compared to oral finasteride, both the oral finasteride 1mg and the topical finasteride 1% showed statistically significant increase in total and terminal hair count and that no significant difference was observed with respect to hairthicknes and hair counts. Authors concluded that “the therapeutic effects of both finasteride gel and finasteride tablet were relatively similar to each other.” When topical finasteride was combined with topical minoxidil, the combination of finasteride with minoxidil was superior to minoxidil alone by itself. Finally, 84.4% of patients who were on oral finasteride for about 2 years and then switched over to topical finasteride with minoxidil maintained good hair density. Thus far, these studies with a total patient count of 268 show that topical finasteride can cause hair growth and have similar efficacy as oral finasteride. Additional large cohort studies are still needed to better evaluate the efficacy of topical finasteride vs oral finasteride.