Mesterolone, also known by its brand name Proviron, is a synthetic androgen and anabolic steroid medication. It is primarily used in the treatment of low testosterone levels in men, a condition known as hypogonadism.

Mesterolone works by replacing or supplementing the natural testosterone produced by the body, helping to restore normal levels of the hormone. This can alleviate symptoms associated with low testosterone, such as reduced libido, erectile dysfunction, fatigue, and mood changes.