Winstrol is a brand name of the synthetic anabolic steroid, stanozolol. Although no longer available in the . under the name of Winstrol, generic versions of stanozolol can still be found. Stanozolol is similar to testosterone and commonly used by veterinarians on debilitated animals (especially dogs and horses) to improve muscle growth, trigger red blood cell production, increase bone density and enhance appetite. It's approved by the . Food and Drug Administration (FDA) for treating anemia and hereditary angioedema (swelling of blood vessels) in people, although a prescription is needed. Winstrol (stanozolol) is a banned performance-enhancing drug, but still used widely by track and field athletes as well as bodybuilders — usually illegally. You should take stanozolol only with the permission and under the care of a physician.