Finasteride is one of the most common drugs used to treat male hair loss. It’s an example of a 5-alpha reductase inhibitor (5-ARI), which is a type of medication that blocks the activity of an enzyme called 5-alpha reductase. Finasteride prevents this enzyme from transforming testosterone into dihydrotestosterone (DHT), which is the main contributor to male pattern hair loss.
Once-daily oral dosing of finasteride has been shown to reduce blood DHT levels by about 70% (Gormley et al., 1990). This dramatic reduction in DHT levels helps stop the progression of hair follicle miniaturization, which is responsible for the tell-tale signs of male pattern baldness.
In this article, we’ll go into detail about what types of hair loss can be treated with finasteride, whether finasteride for hair loss is effective and if this effectiveness changes over time. We’ll also answer commonly asked questions about the best age to start using finasteride for hair loss and whether you have to take finasteride for the rest of your life.
Taking finasteride for hair loss: What types of hair loss does it treat?
Finasteride is approved for the treatment of androgenetic alopecia at a 1mg daily dose. It’s not used to treat other types of hair loss such as traction alopecia, scarring (cicatricial) alopecia, alopecia universalis or telogen effluvium. This is because DHT levels are not a causal factor in these other types of hair loss.
Outside of the FDA-approved 1mg oral dose, other forms of finasteride, such as topical finasteride, do exist. These can still be prescribed to patients for hair loss at custom concentrations. However, you should be aware that these custom formulations are not FDA-approved.