There are a plethora of bulking supplements on the market today, many claiming to achieve identical results, and all of them claiming to be safe. One popular drug is Ostarine. What is Ostarine, what does it do, and is it safe?

Ostarine is a selective androgen receptor modulator drug that binds to androgen receptors, mimicking the effects of boosted testosterone. This, in turn, causes the body to produce more muscle faster. However, the drug is not approved for human use in its original form, and caution should be used with Ostarine as there are some negative side effects.

Keep reading to learn more about Ostarine, how it works, its effects, drawbacks, and alternatives to this drug.

What is Ostarine?

Ostarine (also known as Enobosarm and MK-2866) is a selective androgen receptor modulator designed and developed by GTx Incorporated. Originally devised in 1997 as a drug to help combat muscle wasting and osteoporosis in elderly adults, Ostarine has some possible uses as a muscle-bulking agent.

However, the drug was never approved for use in humans, and can not be legally obtained or used in its original form. Testing for various medical uses is still ongoing, and the drug has yet to be released and approved by the FDA.

In black market forms, this drug has gained popularity in recent years as a bulking agent, used by bodybuilders to help increase muscle mass and encourage faster growth.

Ostarine has also found its way into a variety of health supplements as an added ingredient instead of the sole ingredient. This sometimes allows products containing Ostarine to fly under the radar legally, though its use in professional sports is still banned.

Is It Legal to Use Ostarine?

In its original and pure form, Ostarine has never been approved for public use. Thus, obtaining pure prescription Ostarine for any reason is still not an option.

But the basic chemical composition of Ostarine has found its way into a variety of legal-for-casual-use products, especially dietary supplements meant to increase muscle mass. But don’t try to use products containing Ostarine in a professional sports context.

The World Anti-Doping Agency has banned all selective androgen receptor modulator drugs and will land you in legal and professional trouble if found in your system as a pro athlete.

But supplements simply containing Ostarine are still legal in most countries and can be bought at many nutrition stores for those simply seeking visible gains without using those gains to win in professional arenas.


So yes, if you find a bulking supplement at your local health store containing Ostarine, it’s perfectly legal. Be careful of gray market or online sales of substances purporting to be Ostarine, however, as the number of adulterated, fake, and inaccurately labeled supplement substitutes is growing.

How Does Ostarine Work?

While Ostarine may not be legal in its most essential prescription form, it can still be helpful to understand how this substance works, and what it does to the human body.

Ostarine mimics testosterone and binds to androgen receptors in the muscles, connective tissue, and bones. This gives the body the impression that more testosterone is being naturally produced, and the increased androgen receptor activity triggers an increase of muscle mass and endurance, in those parts of the body where the Ostarine has formed a bond with receptors.

This mechanism differs from that of androgen anabolic steroids (or aas) in that the binding is more selective and less general; while aas substances bind to androgen receptors all over the body, Ostarine binds only to androgen receptors in muscles, connective tissue, and bones.

Thus while the effects of androgen anabolic steroids can be more intense, visible, and aesthetically preferable, Ostarine and similar substances impact the body in a more specific and milder way and produce fewer of the associated negative aas side effects.

Through a gentler hormonal mimicry, Ostarine works to activate the muscle stem cells that are crucial to muscular tissue growth and repair. Cells in connective tissue are also strengthened, leading to greater strength and endurance as your muscle mass grows.

All this happens while the rest of the body is largely spared the less-than-optimal effects of aas drugs, including lower sperm count, impotency, and hair loss.

Why Choose Ostarine?

For the reasons mentioned above, many bodybuilders prefer Ostarine and see it as less risky than traditional steroids.

Ostarine is a bit gentler on the system than androgen anabolic steroids and is better able to target muscle growth. The body tends to acclimate better to this substance and is not inundated with false testosterone signals, nor with an overload of responsive estrogen production.

Ostarine is especially helpful for

  • Building muscle mass
  • Increasing lean muscle mass (while avoiding water retention)
  • Improving muscle endurance and recovery rates
  • Stronger joints and tendons.

The very properties which made Ostarine a possible help to elderly adults struggling with muscle wasting and bone fragility can help an athlete get stronger and improve bone density at the same time.


As you bulk up more naturally, the drug may also help you reduce fat, speed up your metabolism, and improve physical stamina. This is not something reported by all users, however, and your mileage may vary here.

Many bodybuilders prefer supplements with Ostarine thanks to the milder side effects (note that milder does not mean non-existent), targeted effects on muscle growth, and less impact on male reproductive health. You’ll also notice more natural gains over a longer period, allowing your body to gain strength and endurance at a pace that’s right for you.

Even better, as an sarm, Ostarine is generally safer and easier for female lifters to use, though in smaller doses than men. As testosterone receptors in only the muscles and bones are targeted, women experience fewer unwanted masculinizing side effects (such as a deepened voice or extra body hair).

So if you do choose a supplement with Ostarine, how should you take it, and what’s a healthy and safe cycle for this substance?

How Should I Dose With Ostarine?

Studies done with Ostarine focusing on elderly patients indicate that a 3 mg per day dosage is helpful in increasing muscle mass. Should you increase that amount?

Keep in mind that legal supplements will contain a variety of ingredients as opposed to pure Ostarine. 20 to 25 mg of Ostarine supplement per day for a male should be a safe and helpful dosage, but be sure to watch for any adverse effects or reactions.

For women using Ostarine, 10 mg per day is recommended to account for smaller body mass and hormone differences. While some in the bodybuilding community insist that women can handle up to 20 mg of Ostarine, we don’t recommend going that high. Women should keep their doses lower consistently, and use a healthy lifestyle and patience rather than increasing doses.

Both sexes can generally safely cycle for 6 weeks, followed by another 6 weeks of recovery. Your recovery from Ostarine may not need a counter-supplement, but you should still allow your body to rest from the supplement to reduce the chances of long-term harm.

Positive results noted by those using the supplements include noticeable weight loss, fat reduction, and bigger and better-looking muscles. Energy levels also improved, and the metabolism seemed to speed up in some cases.

Though typical androgen anabolic steroid-like effects are rare, Ostarine may agree more or less with your system. If you feel unwell or notice adverse reactions, stop immediately. With that in mind, Ostarine is not perfect, and some concerning side effects exist, especially if the substance is overused.

Are There Side Effects to Ostarine?

While side effects are typically minimal compared to those of classic steroids, some risks exist with the use of Ostarine supplements.

Over-use of Ostarine has been linked to a lowering of natural testosterone levels. While the compound binds only to specific muscle receptors, an excess of Ostarine even at a muscular level can trigger the body to produce less testosterone, as your endocrine system will assume there’s already too much being made.


A drop in natural testosterone can lead to a lower sperm count, infertility, and skin problems, the very things many users seek to avoid. Similar negative effects can sometimes be observed in men who use Ostarine far beyond the generally recommended 6-week dosing cycle.

While Ostarine is typically gentler on the liver than a true steroid, there are still reports of liver damage while using Ostarine. As Ostarine supplements become more popular and more widely used, we may indeed see more cases of negative side effects or organ damage associated with the drug.

This is especially true for those who already have a sensitive or weakened liver. If your liver is already unhealthy or struggling to process compounds, we suggest skipping Ostarine and opting for natural, less potentially harmful bulking tactics.

It’s important to go slowly with any bulking supplement, not exceed generally advised doses, and take your body off of the supplement after 6 weeks and allow for recovery. In addition, beware of Ostarine supplements sold online, as these may contain unlisted, unapproved, unsafe, or toxic ingredients.

What Alternatives to Ostarine Exist?

While Ostarine is quite a bit safer than traditional steroids, you may wish to bulk up more naturally without the help of supplements. You may also have a weakened liver and don’t want to risk possible organ damage. So how can you bulk up and increase muscle mass naturally?

Some of the simplest ways to naturally boost testosterone, stamina, and muscle mass involve living a healthy lifestyle, eating well, and reducing stress in your daily life.

Foods to select to naturally bulk up and increase testosterone include nuts, fatty fish (like salmon), leafy greens, eggs, whole grains, and whole foods.

This means foods that you buy from whole, uncooked, minimally processed ingredients and then cook at home. Think cookbook-type recipes. While more time-consuming, these recipes and foods can do wonders for your health, boost healthy hormone levels naturally, and help you lose weight.

Foods to avoid include refined sugars, processed foods, junk food, fast food, anything with artificial colors or flavors, energy drinks, and artificial sweeteners. Need to sweeten your cereal or plain yogurt? Try honey, agave nectar, maple syrup, or another less refined sweetener. And replace your Red Bull with plain, pure drinking water.

In addition to eating a healthy and natural diet, getting plenty of sleep (8 hours), avoiding stress, getting out in nature for some fresh air, and having a healthy mental and spiritual life can all balance your hormone levels and improve overall health. The healthier your cells are, the more optimized they’ll be for gains and recovery.

Instead of doom-scrolling or vegging out in front of Netflix, go for a walk or a bike ride. Try yoga, deep breathing, and sitting in your backyard with some music on. Reduce your alcohol intake, too. Increased alcohol consumption has been linked to lower testosterone levels, so cut back on beer and have some water, tea, or coffee instead.


Final Thoughts

Ostarine is a selective androgen receptor modular drug that binds to androgen receptors in the muscles, bones, and connective tissue to promote muscle growth and bone density increases. It’s unique in that instead of binding to androgen receptors all over the body, it binds specifically to those found within muscle and bone tissue, making it less potent and generally safer than androgen anabolic steroids.

While not legal in its pure and prescription form, Ostarine can be found as an added component to a variety of legal-for-casual-use supplements. Just don’t use them within the context of professional sports, as they’re banned by the World Anti-Doping Agency in pro sports contexts.

Ostarine users reported more normative hormone levels, fewer side effects, gentle yet noticeable gains over time, and improved energy levels. Women on Ostarine reported few to no masculinizing effects, and the supplements are preferred by female bodybuilders.

Still, some liver damage has been reported with long-term Ostarine use, and it’s safest to cycle the supplement for 6 weeks followed by a 6-week recovery. Men typically benefit from 20 to 25 mg daily while women are safest at 10 mg daily.

Alternatives to Ostarine include a whole foods diet rich in vegetables, fatty fish, nuts, whole grains, and natural ingredients. Getting plenty of sleep can also naturally boost testosterone, as can lowered stress levels, exercise, fresh air, and good mental and spiritual health.