Stanozolol, sold under the name Winstrol, was developed by Winthrop Laboratories in 1962. It is a synthetic anabolic steroid derived from testosterone, and has been approved by the FDA for human use.

Unlike most injectable anabolic steroids, Stanozolol is not esterified and is sold as an aqueous suspension. The drug has a large oral bioavailability, due to a C17 ?-alkylation which allows the hormone to survive first pass liver metabolism when ingested. Because of this, Stanozolol is also sold in tablet form

Stanozolol has been used on both animal and human patients for a number of conditions. In humans, it has been demonstrated to be successful in treating anaemia and hereditary angioedema. Veterinarians may prescribe the drug to improve muscle growth, red blood cell production, increase bone density and stimulate the appetite of debilitated or weakened animals.

Stanozolol is one of the Anabolic steroids commonly used as an ergogenic aid and is banned from use in sports competition under the auspices of the International Association of Athletics Federations (IAAF).

Used in bodybuilding, typically "stacked" with other testosterone-based anabolic steroids. Stanozolol is liked by many due to the fact it causes strength increases without excess weight-gain, promotes increases in vascularity, and will not convert to estrogen. It also does not cause excess water retention, and even sometimes is thought to have a diuretic effect on the body.

Stanozolol is commonly used by athletes and bodybuilders alike to lose fat while retaining lean body mass. It is usually used in a ripping cycle, to help preserve lean body mass while metabolizing adipose, although it has not been proven conclusively that it has any special fat-burning properties.

It is presented most commonly as a 50mgs/cc (cubic centimter) injection or a 50 mg tablet. However, recently 100mgs/cc versions have become available. A common dosage can be 25-100mgs/day, with optimal results usually seen at 50mgs/day. It is micronized in a water-based suspension and does not have a typical elimination half-life. Authentic Stanozol can easily be seen, because it will separate in its container if left undisturbed for a number of hours (the micronized crystal will fall to the bottom, and the water suspension will rise to the top). It has a white, milky colour.

It should be taken no less than 48 hours apart, with some users preferring to inject every day, or even twice a day, to maintain serum levels.

The drug has been known to cause masculinising side-effects in women with doses as low as 2 mg per day, and liver damage has been known to occur with extended usage of larger doses.