Topical vs. oral finasteride for hair loss
Finasteride is more commonly known for its tablet form to treat benign prostatic hyperplasia (BPH), brand name Proscar and male pattern hair loss (alopecia), brand name Propecia. It was originally marketed for BPH at 5mg daily, one of the side effects noticed with this medication was the increasing hair thickness and was then approved after being studied for alopecia. Although given at a lower dose of 1mg daily for alopecia, finasteride, when taken orally, can still cause side effects common with 5mg daily such as decreased libido, erectile dysfunction and other sexual adverse experiences. These side effects may steer patients away from wanting to take oral finasteride for alopecia.
Topical finasteride provides localized treatment for hair loss without the systemic adverse experiences. In one study, 0.25% topical finasteride showed similar therapeutic effects when compared to 1mg tablet form. It has shown its efficacy in hair loss treatment through very little scientific evidence. However, looking at the dosage forms and mechanism of action, some implication can be made. Systemically, as a 5-alpha reductase inhibitor, reduces the conversion of testosterone to DHT. Higher levels of DHT are found in miniaturized hair follicles (consistent in male pattern baldness) and finasteride reduces scalp and serum DHT levels when given orally. Reducing serum DHT levels results in other effects on the body. Topically applying finasteride may localize reduction in DHT levels to just the scalp, avoiding those unwanted effects.
Topical finasteride is not commercially available or FDA approved for hair loss and must be compounded. It may provide an option to patients suffering from hair loss offering a localized treatment option in efforts to reduce risk of systemic side effects.
- Propecia (finasteride) prescribing information. Whitehouse Station (NJ): Merk & Co., Inc; 1997.
- Hajheydari Z, Akbari J, Saeedi M and Shokoohi L. Comparing the therapeutic effects of finasteride gel and tablet in treatment of the androgenetic alopecia. Indian J Dermatol Venereol Leprol. 2009 Jan;75(10):45-71.