Finasteride is an active pharmaceutical ingredient used in the treatment of benign prostatic hyperplasia (BPH) and male pattern hair loss. It belongs to the group of 5-alpha-reductase inhibitors and reduces the levels of dihydrotestosterone (DHT) in the body. In patients with BPH, it helps decrease prostate size and improves urinary symptoms. In men with androgenic alopecia, it helps slow down and halt hair loss by affecting the hormonal mechanisms associated with this type of hair loss.