Very little testosterone is converted to DHT in the scalp. Testosterone is converted to DHT via 5-alpha-reductase in the testes and prostate. Therefore Finasteride should only be effective at blocking the conversion of testosterone to DHT — so using it topically should have very little effect.
A better approach might be to block the androgen receptors in the scalp in order to prevent DHT from binding to the receptors. I have researched this quite a bit and there are several ways of doing it. I have considered adding receptor blockers to the topical and it’s something I would consider looking into again in the future. I’ll try to keep you posted.
Having said that, several studies have explored the efficacy of topical finasteride for treating androgenetic alopecia (male and female pattern hair loss), and the results seem far more promising than I expected. Here are some key findings from the research:
Multiple studies have shown that topical Finasteride significantly reduces scalp DHT levels. One study reported a 68-75% reduction in scalp DHT with topical finasteride compared to oral forms, making it effective while potentially minimizing systemic side effects​.
Across several clinical trials, participants experienced an increase in both terminal hair count (thicker, longer hairs) and total hair density after using topical finasteride. These results were observed both with topical finasteride alone and in combination with minoxidil, which seems to enhance absorption and effectiveness​.
The safety of topical Finasteride has been highlighted in various studies. Unlike oral Finasteride, which is associated with potential systemic side effects such as sexual dysfunction, topical finasteride has shown no significant impact on serum testosterone or major adverse effects in the short term​.
Overall, the studies suggest that topical Finasteride is a safe and effective alternative to oral Finasteride for individuals seeking to treat hair loss with reduced risk of systemic side effects. However, more research is needed to optimize dosing, formulation, and long-term effects.