Finasteride, also known by its brand name, Propecia, works by blocking the enzyme 5α-Reductase. 5α-Reductase converts testosterone (the male sex hormone) to dihydrotestosterone (DHT), a hormone that shrinks hair follicles until they’re unable to grow hair, causing hair loss.
This lowers DHT levels by 70%-90% and increases testosterone levels in the body, promoting hair growth among follicles that were previously affected by DHT.
You may wonder: Does finasteride improve diameter in new and existing hair? After all, it does initiate hair regrowth in damaged follicles!
The answer isn’t black and white.
According to a 2003 study published in the Journal of Investigative Dermatology Symposium Proceedings, finasteride decreases hair shedding and can stop hair loss among 90% of men. The same study revealed that 65% of men noticed stimulated hair regrowth, reversed miniaturization, and thicker hair shaft diameter of existing hair.
It also reduced the rate of hair loss while preventing further shedding, thus slowing down the natural balding process.
As you can see, there’s a ray of light at the end of the tunnel.
Keep in mind that while finasteride increases hair thickness in areas with miniaturization, it does little for restoring growth in balding areas, especially if the hair loss is caused by genetics, hormones, and underlying health conditions.
If your hair loss isn't caused by any of these factors, you can get the most out of your treatment by —