Stanozolol (Winstrol)

Stanozolol, sold under the brand name Winstrol, is a man-made anabolic-androgenic steroid (AAS, a lab-made relative of testosterone built to grow muscle) made from dihydrotestosterone. Most people know it from sports history: it’s the steroid that cost Ben Johnson his 1988 Seoul Olympic 100 m gold medal. In fitness circles it has a big reputation for giving a lean, “dry” look — but the solid human research backing up those physique benefits is thin, while the proof that it harms your cholesterol and liver is strong. It is not a peptide and it is not a SARM.

What it is

Stanozolol is a man-made anabolic-androgenic steroid built from dihydrotestosterone (DHT, a strong natural form of testosterone). What makes it unusual is a small ring of atoms (a pyrazole ring) attached to its core structure, which makes it a “heterocyclic” steroid. Like other steroids you can take as a pill, it has been 17α-alkylated (a tweak that adds a methyl group at a specific spot). That methyl group lets the drug survive its first pass through the liver, which is what makes the pill work when swallowed — but it’s also the very reason all of these “17α-alkylated” oral steroids are hard on the liver.

How does it work? Stanozolol switches on the androgen receptor (the docking point inside cells that testosterone-like hormones act through). It doesn’t grip that receptor very tightly, but it leans more toward building muscle than toward other male-hormone effects. It is also non-aromatizable, meaning the body can’t turn it into estradiol (a form of estrogen) — so by itself it doesn’t directly cause estrogen-type effects, although it can still shut down your own natural testosterone. It also lowers sex-hormone-binding globulin (SHBG, a protein that ferries sex hormones around the blood). Historically it came both as tablets and as an injectable water-based (microcrystalline) suspension. Worth noting: unlike many oil-based injectable steroids, this injectable is a water suspension, so the “ester-timing” ideas people apply to those oil-based drugs don’t apply here.

The claims

In medicine, stanozolol was used to prevent attacks of hereditary angioedema (HAE, an inherited condition that causes sudden, severe swelling) — cutting how often and how badly attacks happened — and to treat some anemias (low red blood cell counts). It was also used or tested for wasting/debilitating illnesses, osteoporosis (thinning bones), and venous insufficiency/lipodermatosclerosis (poor blood return and skin hardening in the legs). For HAE, a group of so-called attenuated (milder) androgens — danazol, stanozolol, oxandrolone — were a go-to long-term preventive pill for decades. They work by prompting the liver to make more C1-esterase inhibitor and raise C4 levels (both are proteins that keep the swelling response in check). These have now largely been replaced by newer, more targeted drugs (C1-INH concentrates, lanadelumab, berotralstat, and others).

In sports and bodybuilding, people reach for stanozolol to hold onto lean muscle, gain strength, and get a “dry/hard” look while losing fat — partly because it doesn’t convert to estrogen, so it causes little water retention.

What the evidence actually shows

Its reputation for performance and looks comes mostly from informal, uncontrolled use and personal reports. Solid, controlled human studies on whether stanozolol actually builds muscle or strength in healthy athletes are limited.

• HIV/AIDS wasting: the human data people point to are weak. Berger et al. (1993) described 3 AIDS patients with HIV-1 wasting myopathy (severe muscle loss from HIV) who improved on anabolic steroids — better strength, muscle bulk, body weight, and well-being. But this was an uncontrolled case series (a report of a handful of patients with no comparison group), not a randomized trial. It’s a starting hint, not proof that the drug works.
• Lipid and metabolic effects (well documented): controlled human studies reliably show stanozolol sharply lowers HDL cholesterol (the “good” cholesterol). Thompson et al. (JAMA 1989) found oral stanozolol cut HDL-C by about 33% and the HDL2 subfraction by about 71%, dropped apolipoprotein A-I (a key protein in good cholesterol) by roughly 40%, and raised LDL-C (the “bad” cholesterol) by about 29% — far worse for cholesterol than testosterone given by injection into muscle. Other controlled work shows it lowers lecithin-cholesterol acyltransferase, apolipoprotein D, and Lp(a) — all blood markers tied to cholesterol handling (Albers et al., 1984). Studies in people who lack the enzyme hepatic lipase point to a rise in that liver enzyme as the reason it knocks down HDL (Bausserman et al., 1997).
• Hereditary angioedema: review-level evidence (Bork et al. critical appraisal, 2015) supports the attenuated androgens — including stanozolol — as effective at cutting down attacks, but with a heavy load of side effects when used long term.

The bottom line on the physique claims: the muscle and strength benefits in healthy people rest mostly on low-quality and anecdotal evidence, while the harmful effects on metabolism are clearly proven.

Legal and regulatory status

In the United States, anabolic steroids — including stanozolol — are Schedule III controlled substances under the Controlled Substances Act (a federal classification for drugs with real misuse potential and tight legal limits). They were placed there by the Anabolic Steroids Control Act of 1990 (signed November 1990, effective February 1991), and the category was widened by the Anabolic Steroid Control Act of 2004. Having or selling them without a medical reason is a federal crime. Stanozolol is no longer sold in the US, so anything offered online as “Winstrol” sits completely outside the prescription and regulatory system.

For comparison: clenbuterol is not FDA-approved for humans and is not a scheduled controlled substance (it can be used legally in veterinary settings); HGH is covered by its own law, 21 U.S.C. § 333(e), and is not a controlled substance.

In sport, stanozolol is banned at all times (both in and out of competition) as an anabolic androgenic steroid under WADA (the World Anti-Doping Agency) class S1 (Anabolic Agents), subsection S1.1 (Anabolic Androgenic Steroids). The 2026 List spells out that banned anabolic agents include “other substances with a similar chemical structure or similar biological effect(s), including their esters.” (For comparison: clenbuterol is also in S1, listed under S1.2 — “other anabolic agents”; HGH and hCG fall under S2, Peptide Hormones, Growth Factors, and Related Substances.) Stanozolol is famous in doping history: Ben Johnson was stripped of his 1988 Seoul Olympic 100 m gold after testing positive for it.

Safety

• Liver harm (the trademark danger of 17α-alkylated pills): LiverTox (an NIH reference on drug-related liver injury) lists stanozolol among the alkylated androgens that cause “bland cholestasis” (bile flow stalls, bringing jaundice and itching, often with only a small rise in liver enzymes), peliosis hepatis (blood-filled cysts in the liver that can burst), hepatic adenomas and hepatocellular carcinoma (liver tumors, usually after years of use), and nodular regenerative hyperplasia (an abnormal lumpy regrowth of liver tissue). One documented case (Stępień et al., 2015) describes a 19-year-old amateur bodybuilder who, after injecting stanozolol for about 2 months, developed severe intrahepatic cholestasis (a deep stall in bile flow inside the liver) and acute liver failure — bilirubin, a marker of liver trouble, peaked around 56 mg/dL — and recovered over months. The damage often reverses once the drug is stopped, but it can be severe.
• Heart and cholesterol: a strong, repeatable drop in HDL (“good”) cholesterol — with HDL2 hit hardest — tilts the blood toward an atherogenic pattern (one that encourages clogged arteries), raising worry about faster-developing atherosclerosis. There are also reported effects on the structure and function of the heart’s left ventricle, plus the increased clotting risk that comes with anabolic steroid use in general.
• Shutting down your own hormones and fertility: taking outside androgens suppresses the hypothalamic-pituitary-testicular axis (the brain-to-testes signaling loop that runs natural testosterone). That lowers LH and FSH (the brain’s signaling hormones), which drops your own testosterone, harms sperm production, shrinks the testicles, and can cause infertility that may stick around after stopping. This happens with outside androgens as a group.
• Estrogen effects / gynecomastia: stanozolol itself doesn’t convert to estrogen, so it doesn’t directly cause gynecomastia (male breast tissue growth). But shutting down your own hormone system, or stacking it with steroids that do convert to estrogen, can still throw off the balance between androgens and estrogen.
• Virilization (male traits, especially in women): a deepening voice, hirsutism (unwanted body/facial hair), clitoral enlargement, and disrupted periods — and some of these changes don’t reverse.
• Blood: androgens can raise hematocrit (the share of blood made up of red cells) and cause erythrocytosis/polycythemia (too many red cells), which raises clotting risk.
• Other: concerns about tendons and connective tissue, acne and oily skin, hair loss in people prone to it, fluid and electrolyte shifts, changes in mood and aggression, and — in children — premature epiphyseal closure (growth plates closing early, which can stunt height). The injectable water-based suspension is known for painful reactions at the injection site.

Bottom line

Stanozolol is a 17α-alkylated anabolic-androgenic steroid with a genuine but mostly historical medical role (hereditary angioedema, some anemias) and a notorious doping past. The human evidence that it improves physique and performance is weak and largely anecdotal, while its harms — especially the drop in HDL cholesterol and the liver injury — are well documented. It’s a Schedule III controlled substance in the US, no longer sold there, and banned at all times in sport. The popular picture of Winstrol as a clean way to get “lean and hard” glosses over serious risks to your metabolism and liver.

Evidence grade: 8/10 · Good.

Sources

• LiverTox: Androgenic Steroids (NCBI Bookshelf, NBK548931)
• Stanozolol — Wikipedia
• Thompson PD et al. 1989 — contrasting effects of testosterone and stanozolol on serum lipoprotein levels (JAMA; PMID 2915439)
• Albers JJ et al. 1984 — reduction of LCAT, apolipoprotein D and Lp(a) with stanozolol (Biochim Biophys Acta; PMID 6236850)
• Bausserman LL et al. 1997 — short-term stanozolol on serum lipoproteins in hepatic lipase deficiency (Metabolism; PMID 9284885)
• Berger JR, Pall L, Winfield D 1993 — anabolic steroids in HIV-related wasting myopathy, case series (South Med J; PMID 8351543)
• Stępień PM et al. 2015 — severe intrahepatic cholestasis and liver failure after stanozolol usage (Clin Exp Hepatol; PMID 28856252)
• Critical appraisal of androgen use in hereditary angioedema: a systematic review (Ann Allergy Asthma Immunol 2015)
• DEA Diversion — Anabolic Steroids (Schedule III; ASCA 1990/2004)
• Anabolic Steroids Control Act of 1990 — Congress.gov H.R.4658
• WADA 2026 Prohibited List
• USADA 2026 WADA Prohibited List summary
• 21 U.S. Code § 333 (HGH penalty, subsection (e))