Winstrol — stanozolol

Winstrol is the most widely recognized trade name for the drug stanozolol. Stanozolol is a derivative of dihydrotestosterone, chemically altered so that the hormone’s anabolic (tissuebuilding) properties are greatly amplified and its androgenic activity minimized. Stanozolol is classified as an “anabolic” steroid, and exhibits one of the strongest dissociations of anabolic to androgenic effect among commercially available agents. It also cannot be aromatized into estrogens. Stanozolol is the second most widely used oral steroid, succeeded in popularity only by Dianabol (methandrostenolone). It is favored for its ability to promote muscle growth without water-retention, making it highly valued by dieting bodybuilders and competitive athletes.

Brand name Winstrol, Stanozolol, Azolol, Stanol, Stanozodon, Stanztab, Nabolic Strong, Anabolico Cimol, Stanozoland, Estanozolol, Stanazolic
Androgenic 30
Anabolic 320
Standard Methyltestosterone (oral)
Chemical Names 17beta-Hydroxy-17-methyl-5alpha-
androstanol[ 3,2-c]pyrazole
Estrogenic Activity none
Progestational Activity not significant

Stanozolol History

Stanozolol was first described in 1959. It was developed into a medicine by Winthrop Laboratories in Great Britain. Parent firm (Sterling) filed for U.S. patent on the agent in 1961. Stanozolol was officially released to the U.S. prescription drug market in 1962 under the brand name Winstrol. Stanozolol was initially prescribed for a variety of medical purposes, including the induction of appetite and lean tissue gain in cases of weight loss associated with many malignant and non-malignant diseases, the preservation of bone mass during osteoporosis, the promotion of liner growth in children with growth failure, as an anticatabolic during prolonged corticosteroid therapy or for post-operative and post-trauma (burns, fractures) patients, and even to treat debility in the elderly.

The FDA’s control over the prescription drug market had tightened by the mid-1970’s, and the indicated uses for Winstrol were soon narrowed. During this time the FDA officially supported that Winstrol was “Probably Effective” as an adjunct therapy for treating osteoporosis, and for promoting growth in pituitary-deficient dwarfism. With this position, Winthrop was given more time to sell and study the agent. Winthrop was able to continually satisfy the FDA regarding Winstrol’s validity as a therapeutic agent, and it remained in the U.S. throughout the 1980’s and 1990’s, a time when many other anabolic steroids were disappearing from the marketplace. Stanozolol was also showing some promise during this period for improving red blood cell concentrations, combating breast cancer, and (more recently) treating angioedema, a disorder characterized by the swelling of subdermal tissues, often with hereditary causes.

Winthrop went through a number of corporate changes during the 1990’s, including a 1991 merger with Elf Sanofi to form Sanofi Winthrop. Sanofi Winthrop continued on to sell Winstrol in the U.S. for approximately 10 more years, before finally discontinuing the medication because of “manufacturing issues” (Searle was actually making the product for Sanofi at the time, and had reportedly ceased production). In 2003, the rights to Winstrol were officially transferred to Ovation Pharmaceuticals. Winstrol remains an approved drug on the U.S. pharmaceutical market, although is not under active production by Ovation label. All forms of Winstrol are presently unavailable in the U.S., although the Winstrol brand remains available in Spain. Numerous other brands and generic forms of the drug are produced in other countries, in both human and veterinary drug markets.

How is Stanozolol Supplied

Stanozolol is widely available in both human and veterinary drug markets. Composition and dosage may vary by country and manufacturer. Stanozolol was originally designed as an oral anabolic steroid, containing 2mg of drug per tablet (Winstrol). Other brands commonly contain 5 mg or 10 mg per tablet. Stanozolol can also be found in injectable preparations. These are most commonly water-based suspensions carrying 50 mg/ml of steroid.

Structural Characteristics of Stanozolol

Stanozolol is a modified form of dihydrotestosterone. It differs by:

  • the addition of a methyl group at carbon 17-alpha to protect the hormone during oral administration
  • the attachment of a pyrazol group to the A-ring, replacing the normal 3-keto group (this gives stanozolol the chemical classification of a heterocyclic steroid)

When viewed in the light of 17-alpha methyldihydrotestosterone, the A-ring modification on stanozolol seems to considerably increase its anabolic strength while reducing its relative androgenicity.

Stanozolol has a much weaker relative binding affinity for the androgen receptor than testosterone or dihydrotestosterone. At the same time it displays a much longer half-life and lower affinity for serum binding proteins in comparison. These features (among others) allow stanozolol to be a very potent anabolic steroid in spite of a weaker affinity for receptor binding. Recent studies have additionally confirmed that its primary mode if action involves interaction with the cellular androgen receptor. Although not fully elucidated, stanozolol may have additional (some potentially unique) properties with regard to antagonism of the progesterone receptor, Low Affinity Glucocorticoid-binding Site interaction, and AR/PR/GR independent activities. In therapeutic doses stanozolol does not have significant progestational activity.

Stanozolol is known to strongly suppress levels of SHBG (sex hormone-binding globulin). This trait is characteristic of all anabolic/androgenic steroids, although its potency and form of administration make oral Winstrol particularly effective in this regard. One study with a group of 25 normal males demonstrated a 48.4% reduction in SHBG after only 3 days of use. The dose administered was .2mg/kg, or roughly 18mg for a person weighing 200lbs. Plasma binding proteins such as SHBG act to temporarily constrain steroid hormones from exerting activity in the body, and effectively reduce the available percentage of free (active) steroid. Oral stanozolol may be useful for providing a greater percentage of unbound steroid in the body, especially when taken in combination with a hormone that is more avidly bound by SHBG, such as testosterone.

Stanozolol Side Effects (Estrogenic)

Stanozolol is not aromatized by the body, and is not measurably estrogenic. An anti-estrogen is not necessary when using this steroid, as gynecomastia should not be a concern even among sensitive individuals. Since estrogen is the usual culprit with water retention, stanozolol instead produces a lean, quality look to the physique with no fear of excess subcutaneous fluid retention. This makes it a favorable steroid to use during cutting cycles, when water and fat retention are major concerns. Stanozolol is also very popular among athletes in combination strength/speed sports such as Track and Field. In such disciplines one usually does not want to carry around excess water weight, and may find the raw muscle-growth brought about by stanozolol to be quite favorable over the lower quality mass gains of aromatizable agents.

Stanozolol Side Effects (Androgenic)

Although classified as an anabolic steroid, androgenic side effects are still common with this substance. This may include bouts of oily skin, acne, and body/facial hair growth. Anabolic/androgenic steroids may also aggravate male pattern hair loss. Women are also warned of the potential virilizing effects of anabolic/androgenic steroids. These may include a deepening of the voice, menstrual irregularities, changes in skin texture, facial hair growth, and clitoral enlargement. Additionally, the 5-alpha reductase enzyme does not metabolize stanozolol, so its relative androgenicity is not affected by finasteride or dutasteride. Stanozolol is a steroid with relatively low androgenic activity in relation to its tissue-building actions, making the threshold for strong androgenic side effects comparably higher than more androgenic agents such as testosterone, methandrostenolone, or fluoxymesterone.

Stanozolol Side Effects (Hepatotoxicity)

Stanozolol is a c17-alpha alkylated compound. This alteration protects the drug from deactivation by the liver, allowing a very high percentage of the drug entry into the bloodstream following oral administration. C17-alpha alkylated anabolic/androgenic steroids can be hepatotoxic. Prolonged or high exposure may result in liver damage. In rare instances life-threatening dysfunction may develop. It is advisable to visit a physician periodically during each cycle to monitor liver function and overall health. Intake of c17-alpha alkylated steroids is commonly limited to 6-8 weeks, in an effort to avoid escalating liver strain.

Stanozolol appears to offer less hepatic stress than an equivalent dose of Dianabol (methandrostenolone). Studies giving 12mg of stanozolol per day for 27 weeks failed to demonstrate clinically-significant changes in markers of liver function, including serum aspartate amino-transferase, alanine amino-transferase, gamma-glutamyltransferase, bilirubin, and alkaline phosphatase. Relative hepatotoxicity increases as the dosage escalates, so hepatic dysfunction should still be a concern. In rare instances, high doses (alone or in combination with other steroids) have been implicated in cases of serious life-threatening hepatotoxicity in bodybuilders. Injectable stanozolol has also been implicated in severe hepatotoxicity in an otherwise healthy bodybuilder, and should not be used as an alternative medication when liver toxicity precludes oral stanozolol use.

The use of a liver detoxification supplement such as Liver Stabil, Liv-52, or Essentiale Forte is advised while taking any hepatotoxic anabolic/androgenic steroids.

Stanozolol Side Effects (Cardiovascular)

Anabolic/androgenic steroids can have deleterious effects on serum cholesterol. This includes a tendency to reduce HDL (good) cholesterol values and increase LDL (bad) cholesterol values, which may shift the HDL to LDL balance in a direction that favors greater risk of arteriosclerosis. The relative impact of an anabolic/androgenic steroid on serum lipids is dependant on the dose, route of administration (oral vs. injectable), type of steroid (aromatizable or non-aromatizable), and level of resistance to hepatic metabolism. Stanozolol has a strong effect on the hepatic management of cholesterol due to its structural resistance to liver breakdown, non-aromatizable nature, and route of administration. Studies using an oral dose of 6 mg per day for six weeks demonstrated a mean serum HDL reduction of 33% in healthy male weight-training subjects, which was combined with a 29% increase in serum LDL. Anabolic/androgenic steroids may also adversely affect blood pressure and triglycerides, reduce endothelial relaxation, and support left ventricular hypertrophy, all potentially increasing the risk of cardiovascular disease and myocardial infarction.

Injectable stanozolol has also been documented to produce strong negative changes in serum lipids. One study was carried out on a group of 12 healthy male subjects, and demonstrated a measurable reduction in HDL cholesterol values, as well as an increase in LDL and total cholesterol values, following a single injection of 50 mg. These changes persisted for 4 weeks after the drug was administered, and represent a potential increased risk for developing arteriosclerosis. Injectable stanozolol should not be used as an alternative medication when cardiovascular risk factors preclude oral stanozolol use.

To help reduce cardiovascular strain it is advised to maintain an active cardiovascular exercise program and minimize the intake of saturated fats, cholesterol, and simple carbohydrates at all times during active AAS administration. Supplementing with fish oils (4 grams per day) and a natural cholesterol/antioxidant formula such as Lipid Stabil or a product with comparable ingredients is also recommended.

Stanozolol Side Effects (Testosterone Suppression)

All anabolic/androgenic steroids when taken in doses sufficient to promote muscle gain are expected to suppress endogenous testosterone production. Stanozolol is no exception, and is noted for its strong influence on the hypothalamic-pituitary-testicular axis. Clinical studies giving 10 mg per day to healthy male subjects for 14 days caused the mean plasma testosterone level to fall by 55%. Without the intervention of testosterone-stimulating substances, testosterone levels should return to normal within 1-4 months of drug secession. Note that prolonged hypogonadotrophic hypogonadism can develop secondary to steroid abuse, necessitating medical intervention.

Stanozolol Administration (General)

Studies have shown that taking an oral anabolic steroid with food may decrease its bioavailability. This is caused by the fat-soluble nature of steroid hormones, which can allow some of the drug to dissolve with undigested dietary fat, reducing its absorption from the gastrointestinal tract. For maximum utilization, oral forms of stanozolol should be taken on an empty stomach.

There can be large discrepancies in the steroid particle size between injectable stanozolol preparations. For example, Winstrol from Zambon (Spain) was designed for human use, and uses a refined powder that will pass through a 27-gauge needle. Winstrol-V is a veterinary product in the U.S. and Canada, and has larger particles that will jam in needles smaller than 22-gauge. Solutions that utilize a larger particle size may also cause more discomfort at the site of injection. Injectable forms of stanozolol can be taken in measured oral doses should injection prove intolerable.

Stanozolol Administration (Men)

The original prescribing guidelines for Winstrol called for a daily dosage of 6 mg, which was administered on a schedule of one 2 mg tablet three times per day. The usual dosage for physique- or performance-enhancing purposes is between 15 mg and 25 mg per day, or three to five 5 mg tablets, taken for no longer than 6-8 weeks. Injectable Winstrol is generally recommended at a clinical dosage of one 50 mg injection every 2-3 weeks.

When used for physique- or performance-enhancing purposes, a dosage of 50 mg every other day is most commonly applied. Veterinary stanozolol preparations with a larger particle size will be more slowly dispersed by the body, and are commonly given at 75 mg every third day. Doses of 50 mg per day with injectable stanozolol are not uncommon, although probably not advised. Note that injectable forms of the drug are expected to have, milligram for milligram, a greater anabolic effect than oral.

Stanozolol is often combined with other steroids for a more dramatic result. For example, while bulking one might opt to add in 200-400 mg of a testosterone ester (cypionate, enanthate, or propionate) per week. The result should be a considerable gain in new muscle mass, with a more comfortable level of water and fat retention than if taking a higher dose of testosterone alone. For dieting phases, one might alternately combine stanozolol with a nonaromatizing steroid such as 150 mg per week of a trenbolone ester or 200-300 mg of Primobolan). Such stacks are highly favored for increasing definition and muscularity. An in-between (lean mass gain) might be to add in 200-400 mg of a low estrogenic compound like Deca-Durabolin (nandrolone decanoate) or Equipoise (boldenone undecylenate).

Administration (Women)

The original prescribing guidelines for Winstrol called for a daily dosage of 4 mg (one 2mg tablet twice daily) with young women particularly susceptible to the androgenic effects of anabolic steroids. This dosage was increased to 6mg (the same as the recommended dose for males) when necessary.

When used for physique- or performance-enhancing purposes, a dosage of 5 mg to 10 mg daily is most common, taken for no longer than 4-6 weeks. Injectable Winstrol is generally recommended at a clinical dose of 50 mg every 2-3 weeks. The injectable is usually not advised with women for physique- or performance-enhancing purposes, as it allows for less control over blood hormone levels. Those women who absolutely must use the injectable commonly administer 25 mg every 3 or 4 days. Although this compound is weakly androgenic, the risk of virilization symptoms cannot be completely excluded, even at therapeutic doses.

Stanozolol Availability

Stanozolol remains widely available as a pharmaceutical product. Its production has been shifting to less regulated markets (mainly in Asia) in recent years, however, which likely reflects declining interest in using stanozolol as a medicinal product in the West, and the continuing high demand for this drug among athletes and bodybuilders. In reviewing some of the more popular products and changes on the global pharmaceutical market, we have made the following observations.

British Dispensary in Thailand makes a stanozolol product. Their trade name for the drug is Azolol, and it contains 5 mg of steroid in a 400 tablet bottle. The bottle itself looks very similar to that of Androlic, with dark plastic and a shiny chrome top. Be sure to look for the company’s holographic sticker when shopping.

Stanol (Thailand) is now sold as a generic drug under the March Pharmaceuticals label, though is in the same recognizable white bottle with green-shaded label. The product contains 5 mg of steroid per tablet, and each bottles holds 200 tablets. To deter counterfeiting, the bottle now carries a holographic sticker on the front that bears the company logo.

Acdhon in Thailand makes Stanozodon, which comes in the old industry standard of 2 mg of steroid per tablet. It is packaged in bottles of 1,000. Counterfeits are not known to be a problem at this time although the product is not widely distributed on the black market either.

Unigen markets the product Stanztab in Thailand. It contains 10 mg per tablet, and is packaged in foil and plastic strips of 10 tablets each (5 strips per box).

Winstrol tablets and injectable ampules are still produced in Spain, by Desma. This remains the most popular stanozolol injectable in Europe. All boxes are protected with a holographic sticker, which carries the company logo embedded into the image. Note that highly accurate counterfeits are currently in circulation throught Europe and North America.

The Greek generic by Genepharm is still in production. The product should carry a Greek drug ID sticker on the box, which will show a hidden mark under UV light.

Chinfield makes a 50 mg/mL injectable stanozolol in Argentina called Nabolic Strong. This is the same firm that makes regular Nabolic, a very low dosed (2 mg/mL) version of the same drug. This new product is now much more popular on the black market than the first, due to the more useable dosage. Note that Chinfield prints their logo on the inside of the vial carton, which offers somewhat of a simple security check (obviously one very easy to duplicate).

Anabolico Cimol is an injectable form of stanozolol from Argentina. It comes in multi-dose vials containing 50 mg/mL of the steroid. This item has not been subject to widescale counterfeiting, but also bears no security features that would deter this practice.

Stanozoland from Landerlan in Paraguay is common on the black market, particularly in South America. It comes in the form of a 10 mg tablets, packaged in bottles of 100 tablets each. The company also makes a 50 mg/mL injectable.

Also from Paraguay is a generic stanozolol injectable from Indufar. It contains 50 mg/mL of steroid in a 1 mL glass ampule. Three ampules are packaged per box.

Formula Magistral in Argentina makes generic oral and injectable Estanozolol. The oral comes in the form of 10 mg tablets, loose in pill bottles, while the injectable contains 50 mg/mL in multi-dose vials. These products bear a small square holographic security sticker to deter counterfeiting.

The veterinary compounding pharmacy SMP in Canada makes a generic injectable in 30 mL multi-dose vials (50 mg/mL). This product is made in limited quantities, however, and is not highly common on the black market.

Stanozolol is produced by Swiss Remedies and available across Europe. Due to numerous fakes of this product, Swiss Remedies offers a convenient online product checker.

Magnus Pharmaceuticals makes the product Stanozolol primarily for the EU and UK markets. Due to fake products appearing on the market, Magnus offers an online checker that lets steroid users verify their product originality.

Stanozolol is produced by Swiss Remedies and available across Europe. Due to numerous fakes of this product, Swiss Remedies offers a convenient online product checker.

Magnus Pharmaceuticals makes the product Stanozolol primarily for the EU and UK markets. Due to fake products appearing on the market, Magnus offers an online checker that lets steroid users verify their product originality.

Bodybuilders reference

Pretty much everything written thus far about Stanozolol injectable was also attributed also to the oral form. It was often said that the oral form is less effective than the injectable. In truth, it was usually due to dosages, and this in turn was due to price. Athletes usually administered a lower dosage orally because it seemed like 25 pills daily was mega dosing. In my personal opinion this was true to a point. Oral use of any 17-alfa-alkylated steroid is hard on the liver. This is because it is difficult for the liver to deactivate these modified testosterone and derivatives. Let me make it clear. Milligram for milligram oral administration of Stanozolol was reported significantly more potent than the injection product (but it is more liver toxic). Oral dosages were commonly broken into 2-3 daily dosages to maintain circulatory androgen elevation. An effective reported daily oral dosage for women was 10-15mg and for men 20-30. However, this listed male dosage was not as effective (or as toxic) as the 30-50mg daily dose range.

Male athletes reported the practice of stacking 40-50mg of Stanozolol daily with 300-400mg weekly of a nandrolone provided significant lean muscle tissue augmentation with good post-cycle retention. For “bulking” purposes many reported the use of this drug with a testosterone at an average reported dosage of 200-600mg weekly resulted in “amazing strength and weight gains” and improved post-cycle lean mass retention.

Women athletes commonly reported the use of Stanozolol at a dosage of 10-15mg daily with 50-100mg of a nandrolone weekly resulted in a rapid increase in quality lean mass tissue with low water retention and rare virilizing negative side effects.

Anabolic Steroid Guide reference

Much of what has been said about the injectable Winstrol is more or less also valid for the oral Winstrol. However, in addition to the various forms of administration there are some other differences so that a separate description-as with Primobolan-seems to make sense. For a majority of its users Winstrol tablets are noticeably less effective than the injections. We are, however, unable to give you a logical explanation or scientific evidence for this fact. Since the tablets are I 7-alpha alkylated it is extremely unlikely that during the first pass in the liver a part of the substance will be deactivated, so we can exclude this possibility.

One of the reasons for the lowered effectiveness of the tablets, in our opinion, is that most athletes do not take a high enough quantity of Winstrol tablets. Considering the fact that the injectable Winstrol Depot is usually taken in a dosage of 50 mg/day or at least 50 mg every second day and when comparing this with the actual daily quantity of tablets taken by many athletes, our thesis is confirmed. Since, in the meantime, most athletes only get the 2 mg Winstrol tablets by Zambon one would have to take at least 12-25 tablets daily to obtain the quantity of the substance one receives when injecting. For two reasons, most athletes, however, cannot realize this. On the one hand, at a price of approximately $0.70 - $1 for one 2 mg tablet on the black market the cost for this compound is extremely high. On the other hand, after a longer intake such a high quantity of tablets can lead to gastrointestinal pain and an undesired increase in the liver values since the tablets as already mentioned are. 1 7-alpha alkylated and thus are a considerable stress on the liver. Male athletes who have access to the injectable Winstrol Depot should therefore prefer this form of administration to the tablets. Women, however, often prefer the oral Winstrol This, by all means, makes sense since female athletes have a distinctly lower daily requirement of stanozolol, usually 10-16 mg/day. Thus the daily quantity of tablets is reduced to 5-8 so that gastrointestinal pain and increased liver values occur very rarely. Another reason for the oral intake in women is that the dosage to be taken can be divided into equal doses. This has the advantage that unlike the 50 mg injections-it does not lead to a significant increase in the androgens and thus the androgenic-caused side effects (virilization symptoms) can be reduced. Athletes who have opted for the oral administration of Winstrol usually take their daily dose in two equal amounts mornings and evenings with some liquid during their meals. This assures a good absorption of the substance and, at the same time, minimizes possible gastrointestinal pain.

Newbies Research Guide reference

Winstrol is a common brand name for the drug stanazolol. Stanazolol is a 17-aa steroid, designed for oral administration but also available in injectable form. Winstrol is classified as an anabolic, exhibiting low androgenic side effects. Its’ anabolic properties however are not dramatic and is often used in combination with other drugs, most commonly during cutting cycles when water and fat retention are a major concern. In the U.S., the Zambon brand name from Spain seems to be the most popular. It is supplied in 2mg tabs and 50mg water-based injectable ampules. Common dosages are 10-25mg/day orally and 25-50 mg daily injected. On the black market, tabs sell for $1-2 each and ampules usually cost $15-20. Obviously Winstrol can be very expensive to use. 30ml of injectable Winstrol-V (U.S. Veterinary product) is usually more cost effective but legitimate bottles are now rarely seen due to strict gov’t control. There are many forms of counterfeit Winstrol, so one should be careful when purchasing this product. The Zambon tabs are pink and come 20 to a strip. The Zambon injectable ampules and American Winstrol-V have been duplicated with good accuracy. One should make sure the water and steroid separate when the vial is left out on a table for some time.


Wlliam Llewellyn (2011) - Anabolics
L. Rea (2002) - Chemical Muscle Enhancement Bodybuilders Desk Reference
Anabolic Steroid Guide
Newbies Research Guide

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