Primary Use: Unlike nearly every other steroid, Proviron is not used for muscle-building. In fact, the drug displays almost no anabolic activity at all. Despite this shortcoming, Mesterolone has retained its popularity due to the unique qualities it possesses. There are 3 primary uses for which this drug is best suited, which are: 1) Its ability to reduce circulating estrogen 2) Its exceptional SHBG binding affinity 3) Its ability to increase libido. Mesterolone reduces circulating estrogen by exhibiting a stronger binding affinity for the aromatase enzyme comparative to testosterone. This directly decreases the amount of aromatase enzyme testosterone has to interact with, thereby decreasing testosterone’s estrogen conversion rate. This reduced estrogen level can have several different effects on the user, such as the prevention of estrogen mediated side effects, to cosmetic enhancements like reduced water retention and increased muscle hardness. Proviron is also frequently used to help maximize the muscle-building potential of one’s cycle by indirectly increasing the level of free testosterone/AAS available to muscle tissue, which it accomplishes by reducing levels of sex hormone binding globulin. Last but not least, Proviron is regularly used for libido enhancement, with many considering it to be the single most effective treatment option for this purpose.