Finasteride is a 5-alpha-reductase inhibitor, which means it blocks the enzyme responsible for converting testosterone into dihydrotestosterone (DHT).
DHT and Hair Loss: DHT is a hormone that contributes to hair follicle shrinkage, leading to hair thinning and eventual hair loss in androgenetic alopecia. By reducing DHT levels, finasteride helps slow hair loss and can even promote regrowth.
DHT and Prostate Health: In BPH, high DHT levels cause the prostate to enlarge. Finasteride reduces prostate size, alleviating urinary symptoms.