In the clinical study that made ostarine widely known, older adults given 3 mg daily for 12 weeks gained an average of 1.3 kg of lean mass. That was without any extra training or diet changes. This single result, from 2011, accounts for most of ostarine’s popularity among SARMs.
However, it was never approved for anything, and it is worth knowing why before you buy it. This covers the origins of ostarine, the major human trials run on it, its effects on bloodwork, and where it stands in Canada.
Three names, one compound
Ostarine, MK-2866, enobosarm and GTx-024 all describe the same substance. The official generic name is enobosarm. Ostarine and MK-2866 are the names that caught on in gyms.
This is a selective androgen receptor modulator, or SARM. It acts on the same receptor as testosterone, although it is not a steroid itself. The company that ran the first human trials was GTx Inc. Veru Inc. owns the program now and has been testing it as a way to protect muscle during weight loss.
The human trials, in order
| Year | Who took part | Daily dose | What happened |
|---|---|---|---|
| 2011 | 120 healthy men over 60 and postmenopausal women | 0.1, 0.3, 1 or 3 mg for 12 weeks | 3 mg added 1.3 kg of lean mass on average and improved physical function |
| 2013 | 159 people with cancer and muscle wasting | 1 or 3 mg for up to 113 days | Lean mass rose 1.5 kg (1 mg) and 1.0 kg (3 mg); placebo barely moved |
| 2024 | Women with advanced hormone-positive breast cancer | 9 or 18 mg | About 3 in 10 had clinical benefit at 24 weeks; no comparison group |
| 2025 | Adults over 60 losing weight on semaglutide | 3 or 6 mg for 16 weeks | 71% less lean mass lost than placebo, according to Veru’s top-line results |
Two things stand out. First, the amounts that produced muscle gain in healthy people were very low, 3 mg or below. Second, the breast cancer study used 9 to 18 mg for an entirely different purpose: slowing tumour growth, not building muscle.
Why it never got approved
The phase 2 results were promising enough that GTx went on to run two phase 3 trials of ostarine in lung cancer patients, called POWER 1 and POWER 2. Both failed to hit their co-primary endpoints in 2013. Early in 2014, the company said the data were not enough to apply for approval.
This is the turning point. Each trial had two targets, lean mass and physical function, and a drug that misses either one does not get approved. Enobosarm missed. That was the end of it until Veru came along with a different use in mind.
What it does to bloodwork
The 2011 trial is the best source here, because it measured healthy people on a known dose:
- HDL dropped. The “good” cholesterol fell 17% at 1 mg and 27% at 3 mg.
- SHBG dropped sharply. Sex hormone binding globulin fell by 61% in men and 80% in women at 3 mg.
- Testosterone fell in men at 1 and 3 mg. Free testosterone did not change significantly in that study.
- One person stopped because a liver enzyme (ALT) rose to 4.2 times the upper limit.
Outside of trials, doctors have published cases of serious liver damage linked to ostarine bought online, among them a 2021 case of cholestatic injury and a 2024 case of a 24-year-old whose bilirubin went above 30 mg/dL. These were not supervised patients on 3 mg.
Our earlier piece on whether SARMs raise testosterone covers the suppression side across other compounds, and the PCT guide covers recovery.
Its status in Canada
Health Canada says SARMs are not authorized in Canada for any use. Its public warning about unauthorized workout products names heart attack, stroke and liver damage as possible risks, and it has seized products labelled as containing ostarine in Quebec, Alberta and B.C.
If you compete, note that ostarine is on the World Anti-Doping Agency’s banned list under S1.2, other anabolic agents. It is banned both in and out of competition, and athletes were still being sanctioned for it as recently as 2025.
The quality problem with SARMs bought online
In 2017, a study published in JAMA tested 44 SARM products bought on the internet. Only 23 of the 44 contained any SARM at all. Only 18 had the amount stated on the label. Nine percent had no active ingredient whatsoever.
That research was not limited to ostarine, but it is the reason to buy from a supplier that stands behind what is in the container, and to be wary of any product priced far below everything else on the market.
Our ostarine
We sell Ostarine MK-2866 at $75 a jar: 60 capsules of 15 mg each. That is well above the 3 mg used in the muscle trials and sits between the two breast cancer doses. It ships to Canada and the US.
It sits in our SARMs range alongside Ligandrol LGD-4033 and RAD-140. If endurance is what you are after, we also wrote about MK-2866 and endurance.
GH Canada sells ostarine for research. Neither Health Canada nor the FDA has approved it for use in people, and this article is not medical advice. Sources: Dalton et al., J Cachexia Sarcopenia Muscle 2011; Dobs et al., Lancet Oncol 2013; GTx company updates 2013 to 2014; Palmieri et al., Lancet Oncol 2024; Veru top-line results, January 2025; Van Wagoner et al., JAMA 2017; Health Canada recalls and advisories; ITA/WADA 2026. Price current October 2026.
