Stanozolol (Winstrol)

What stanozolol is and how it works

Stanozolol is a synthetic derivative of testosterone with a 17α-alkylation. This protects the active substance from rapid breakdown in the liver and makes it effective as a tablet; it is also available as an injection. In the US it was approved in 1962 as Winstrol. According to the FDA database, the product is no longer marketed there today.

At the androgen receptor, stanozolol acts like other steroids: it promotes protein synthesis, has a masculinizing effect and, via the pituitary gland, suppresses the body’s own testosterone production. One peculiarity concerns the liver: stanozolol strongly increases hepatic lipase, by 123 percent in one study, and thereby lowers protective HDL cholesterol. Medical uses also included raising complement factors in hereditary angioedema and the effect on bone. An overview of the substance group is given in the article Anabolic steroids.

What the studies show

Thompson 1989: stanozolol versus testosterone

In a crossover study, 11 weightlifters each took oral stanozolol and injected testosterone for six weeks. Under stanozolol, HDL cholesterol fell by 33 percent, the protective subfraction HDL2 by 71 percent and apolipoprotein A-I by 40 percent; LDL rose by 29 percent. Under testosterone, HDL fell by only 9 percent, and LDL decreased by 16 percent. Weight gain was the same. The authors conclude that the unfavorable effect of oral 17α-alkylated steroids differs from that of testosterone.

Carson 2015: randomized study in venous disease

44 older patients with skin hardening and ulcers on the legs received stanozolol or placebo for up to 6 months, each with compression. In 91 percent of those on stanozolol, HDL fell markedly; liver values rose temporarily. All remained free of symptoms, and the values returned to baseline within two months of discontinuation.

Chesnut 1983: osteoporosis

In a double-blind study with 46 postmenopausal women, total body calcium rose by 4.4 percent over 29 months under stanozolol and remained unchanged under placebo. No difference was found at the forearm. There was no new vertebral fracture in the stanozolol group, and three under placebo. 76 percent of those treated had elevated liver values or other side effects, which, however, never led to discontinuation.

Sloane 2007: hereditary angioedema over decades

21 patients who had been taking stanozolol for 20 to 40 years were examined. 10 experienced treatment-related complaints: hair growth, weight gain, menstrual disorders or postmenopausal bleeding, acne and mood swings; a dose reduction was sufficient in each case. No persistently abnormal liver values were found; HDL was decreased in 5 patients.

Small 1984: hormonal axis in healthy men

In 9 healthy men, testosterone fell by 55 percent after 14 days of stanozolol; LH and SHBG also fell. All changes reversed after discontinuation.

Where the data stop

• Muscle building in healthy people. For the purpose for which stanozolol is taken in strength sports, there is no controlled study. Its reputation for building “dry” muscle without water retention has not been studied in humans.
• The heart over years. The drop in HDL is well measured; whether and how strongly it leads to heart attack or stroke with longer use has not been studied for stanozolol alone.
• Injection versus tablet. The studies mostly tested the tablet. The case report of severe cholestasis concerned the injection; comparative data are lacking.
• Women. Data on women come from osteoporosis and angioedema studies with small doses, not from use in sport.

Status, approval and legal

In Germany, stanozolol is prescription-only (German Prescription Medicines Ordinance, Annex 1). No finished medicinal product approved in Germany was found during research. In the US it had been approved as Winstrol since 1962; according to the FDA database, it is no longer marketed there.

Stanozolol is listed in the annex of the German Anti-Doping Act. Manufacturing, trading and supplying it for doping purposes are prohibited, as are acquisition and possession of a not insignificant quantity for doping in sport; the penalty ranges up to three years, in serious cases up to ten. In sport it is on the WADA Prohibited List under S1.1 and is prohibited at all times.

Safety

Blood lipids and heart: the drop in HDL cholesterol is the best-measured side effect, by one third in strength athletes, in 91 percent of those treated in a placebo-controlled study. At the same time, LDL rises. After discontinuation, the values returned to baseline in the studies; what longer exposure means for the blood vessels has not been studied for stanozolol alone.

Liver: as a 17α-alkylated steroid, stanozolol puts strain on the liver. In studies, liver values rose temporarily in some of those treated. A case report describes severe cholestasis in a 19-year-old after two months of self-use, with bilirubin up to 56.6 mg/dl; the values only normalized five months after discontinuation.

Hormonal axis: after just two weeks, the body’s own testosterone production in healthy men was cut by more than half. In women, hair growth, acne and menstrual disorders have been described.

Mental health: in long-term observation in angioedema, mood swings occurred. On dependence, mood and mortality with non-medical use of steroids as a whole, see Anabolic steroids. Anyone considering stanozolol should have liver values and blood lipids checked by a physician – these are the values that changed fastest in the studies.

Sources

• FDA, Drugs@FDA – Winstrol, NDA 012885: approval 1962, status discontinued
• Thompson PD et al., JAMA 1989 – testosterone versus stanozolol: blood lipids in 11 weightlifters, crossover
• Carson P et al., Int J Low Extrem Wounds 2015 – RCT: liver values and blood lipids under stanozolol, 44 patients
• Chesnut CH et al., Metabolism 1983 – stanozolol in postmenopausal osteoporosis, double-blind, 46 women, 29 months
• Sloane DE et al., J Allergy Clin Immunol 2007 – hereditary angioedema: safety after 20 to 40 years of stanozolol
• Small M et al., Clin Endocrinol 1984 – hormonal changes in 9 healthy men under stanozolol
• Stępień PM et al., Clin Exp Hepatol 2015 – severe cholestasis and liver failure after stanozolol, case report
• German Prescription Medicines Ordinance (AMVV), Annex 1 – prescription requirement
• German Anti-Doping Act (AntiDopG), § 2 to § 4 and annex
• Prohibited list in sport 2026: S1.1 anabolic androgenic steroids, prohibited at all times (WADA Prohibited List)