Finasteride is a medication used to treat male pattern hair loss and benign prostatic hyperplasia (BPH). It works by inhibiting the activity of an enzyme called 5-alpha-reductase, which is responsible for converting testosterone into dihydrotestosterone (DHT). DHT is a hormone that is responsible for the development of male pattern hair loss and BPH. By inhibiting the production of DHT, finasteride can slow down or stop the progression of these conditions. In the case of male pattern hair loss, finasteride helps to prevent hair loss by reducing the amount of DHT in the scalp, allowing hair to grow thicker and stronger. For benign prostatic hyperplasia, finasteride works by reducing the size of the prostate gland and reducing symptoms such as difficulty urinating. It is important to note that finasteride is not a cure for hair loss or BPH but rather a treatment that may slow or stop their progression. Finasteride is usually taken once a day, either in the form of a tablet or a topical solution, and it may take several months for the full effects to be seen.