Ostarine (MK-2866) Review [2019]

What makes Ostarine so unique? Is it suitable for bulking? What should you be aware of when choosing a supplier? Answers to these and other questions are provided in the article below. 

What is Ostarin (MK-2866)?

Ostarin, also known as MK-2866 or Ostamuscle, is a SARM – Selective Androgen Receptor Modulator. As the name suggests, these agents only bind to androgen receptors. These receptors are present mainly in muscles and bones, therefore SARMs cause far fewer side effects than steroids or prohormones. 

sarm mk677 capsulesOstarin was created by GTx Incorporated, a company specializing in the synthesis of highly selective substances, in order to prevent muscle wasting diseases.

Clinical trials conducted on people with severe burns, cancer, end-stage renal failure, osteoporosis, and hypogonadism have confirmed the anabolic effect of Ostarin on muscles and bones. It is also worth noting that no effect on prostate, liver, or hair was observed.  

As you can guess, thanks to its incredible abilities to preserve muscles in unfavorable conditions, MK-2866 quickly gained popularity among athletes.

Ostarine Benefits

  • Increase in muscle mass and strength
    As the main purpose of MK-2866 synthesis was to stop the diseases causing muscle loss, Ostarin has superb anabolic properties. Most people seem to think that Ostamuscle is only suitable for cutting, but this is simply not true. There are dozens of reviews on the Internet from people who have used Ostarina and gained a substantial amount of muscle mass.
    The ability of MK-2866 to build muscles is also confirmed by numerous clinical studies, e.g. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3177038/
    In this study, a group of elderly people took 3mg of Ostarin for 12 weeks. As a result, all participants recorded an improvement in their physical condition and a simultaneous increase in muscle mass and a loss of body fat. Individuals from the group taking 3mg a day gained an average of 1.3kg (2.8lb) of lean muscle mass and lost 0.6kg (1.3lb) of fat.
    In another study, 159 cancer patients were divided into 2 groups which took 1 and 3mg MK-2866 for 4 months respectively. Both groups recorded results similar to those from the first study without any side effects. 
  • Loss of fat tissue
    The most popular purpose for athletes to use Ostarine. Typically, during a chronic calorie deficit, we lose not only fat but also muscle tissue. Thanks to its unique properties, MK-2866 protects muscles during unfavorable conditions, so when cutting, we lose almost only fat. What is more, as we have seen in the studies mentioned above, Ostarin itself accelerates the loss of body fat.
  • Improvement of bone tissue condition
    With age, the density of our bone tissue decreases as a result of lower levels of sex hormones. This often leads to bone diseases such as osteoporosis. Owing to the fact that androgen receptors are also found in bones, Ostarin allows to reverse this process and accelerates the healing rate after fractures. 
  • Protects the heart
    A clinical trial conducted in 120 patients receiving 1mg or 3mg of Ostarin per day showed a positive effect of MK-2866 on the cardiovascular system. All participants noted a decrease in the level of bad HDL cholesterol and triglycerides. 
  • Increases insulin sensitivity
    In the study cited above, Ostarin also decreased the mean blood glucose level of the subjects, thus increasing their insulin sensitivity. It is worth noting here that insulin sensitivity is important not only from the point of view of our health, but also of our sports results – Insulin is one of the most powerful anabolic hormones.

MK-2866 Side Effects

You’re probably wondering if such a strong substance has any unwanted side effects.  

The only side effects reported so far are headaches and back pain. While going through forums, we also came across comments from people using MK-2866, who claimed that they were more lethargic when using Ostaryn. Although I have always felt fantastic when using MK-2866, such side effects are very likely and occur with most highly anabolic substances. Increased sluggishness is associated with increased anabolic processes in the body, and thus a greater need for sleep. 

Remember that Ostarin is one of the mildest SARMs. If you suffer from any side effects not listed above, your Ostarin is probably not really Ostarin. Unfortunately, due to the high price of SARMs, many manufacturers add steroids or prohormones to their products. For this reason, you should always buy SARMs from reliable sources that have a certificate of analysis for each batch. 

Does Ostarine require a PCT?

In most cases, Ostarin does not require any PCT. It is one of the mildest SARMs with virtually no effect on testosterone production.

I personally used 30mg for 16 weeks and did not record any side effects. My pre-cycle testosterone level was 536ng/dl, and 10 days after my cycle was finished, it was 492n/dl. Such differences are absolutely insignificant and within the limits of error. Perhaps to some extent, MK-2866 caused testosterone suppression, but after 10 days there was no trace of it. Differences <100ng/dl may be influenced by many factors: diet, time of examination, amount of sleep, sex, or training.  

Results from using Ostarine

When using MK-2866 in a dose of 30mg a day, you can expect gains of 2-3kg (5-7lb) within 10 weeks. MK-2866 is not as potent anabolic as other SARMs, and for this reason, it is used mainly for reduction in order to maintain as much muscle as possible. Ostarin is also often combined with other SARMs owning to the fact that it has no side effects.  

My personal experience with MK-2866

I’ve used Ostarin countless times in my life. It was part of most of the stacks I’ve been using since I had stopped using steroids. It blends very well with virtually all substances, regardless of whether we are cutting, bulking or treating an injury. In my opinion, this versatility is the main reason why Ostarin is so popular. 

As I mentioned earlier, I had the opportunity to use 30mg of Ostarina solo for 16 weeks during the spring reduction. It was my first ever cutting on SARMs, and I must admit I was pleasantly surprised. Remember that these are the words of a person who has been using steroids for several years. Despite a calorie deficit of 500-800 calories, I kept most of my muscle. Also, my strength did not decrease as drastically as I would have expected. In addition, Ostarin produces a dry look comparable to that of Anavar, which is a very nice bonus, especially during summer. 

Before and After Ostarine

Ostarine dosage

Standard doses of MK-2866 are 20-30 mg per day during both bulking and cutting. 

Frankly speaking, these are the only reasonable doses for this substance. Below 20mg, muscle mass gain is quite low and is actually only suitable for cutting. And above 30mg cycle costs increase disproportionately to the effects – it is cheaper to combine Ostarina with other SARM. 

Best ostarine cycles

What cycle you choose to follow with Ostarin depends on your personal goals. 

If you want to perform a gentle reduction and lose 3-5kg while maintaining your muscles, you only need a dose of 30mg of ostarin a day. Such a dose can be safely used for as long as 16 weeks. The most popular cycle of this type is:

MK-2866 (Ostarine)30mgweek 1-12

In case you need to shed more fat, it is a good idea to combine Ostarin with GW-501516. Both of these substances protect muscles in moments of calorie deficit and have fat burning properties. In addition, GW-501516 significantly accelerates metabolism, which means that you don’t have to increase your calorie deficit so much.

MK-2866 (Ostarine)30mgWeek 1-12
GW-50151610mgWeek 1-12

If you have enough money you can add LGD-4033 in a dose of 5mg per day to this cycle, but it is not a necessity. 

Ostarine is also suitable for bulking. Although it does not yield formidable effects by itself, it definitely demonstrates synergy with other SARMs. This is my favorite stack for bulking which allows you to gain 5-6kg in 10 weeks.

LGD-40335mgWeek 3-8
MK-286630mgWeek 1-8
S2310mgWeek 1-8

Best place to buy Ostarine

Unfortunately, the majority of SARMs present on the American market have little in common with their name. Due to high prices of SARMs in wholesale, a large part of products contains much less substance than it is declared on the label. And it’ s a case when we are lucky… Unfortunately, it is just as common practice to add steroids or prohormones as they are much cheaper. For this reason, SARMs should always and unquestionably be purchased only from reliable sources! The supplier should have a certificate of analysis issued by an external laboratory for every product.

Stores that we recommend:

Proven Peptidesproven peptides logo

Currently, the most popular and trusted shop. They have been present on the market for several years and all this time, except for individual cases of broken bottles during transport, I have not encountered any negative reviews of this company. They offer SARMs only in the form of solutions. Each bottle is accompanied by a pipette and information on the amount of agent corresponding to 1ml of solution. You can also easily obtain a certificate of analysis from an external laboratory.

They are one of the few to offer telephone contact. They also offer the “Peptides Points” loyalty programme, in which the collected points reduce the cost of future orders. Shipping from the USA.

link to their website

Chemyochemyo logo

Relatively young shop. It is quickly gaining popularity, especially among Reddit users. This is caused by relatively low prices in comparison to the competition and high credibility of the shop. The certificate of analysis for each of the products can be downloaded directly from their website.

Just like Proven Peptides, they offer SARMs only in the form of solutions. Unfortunately, there is no pipette attached to the bottles (the store offers 1ml syringes for $1). Shipping from the USA.

link to their website

Swisschemsswisschems logo

The youngest store on the list. It is not very popular at the moment. Unlike its predecessors, it offers SARMs in the form of capsules and injections. Similarly to Chemyo, analysis certificates can be downloaded directly from their website.

Apart from SARMs, SwissChems also offers PCTs, aromatase inhibitors, peptides, nootropics and drugs for erectile dysfunction.

link to their website


Unfortunately, despite the fact that for the last 3 years it has been our favourite shop, we are forced to withdraw our recommendation. In recent months, contact with them has become difficult, shipments come out with a 2-3 week delay, and the quality of products has dramatically decreased. 

I apologize in advance to all the people who bought SARMs from this store in recent weeks based on my recommendation before this review update.

Frequently Asked Questions

Best time to take ostarine?

It is best to take the MK-2866 in the morning before your first meal. This will ensure the best possible absorption. However, SARM intake with meals does not significantly affect their absorption – the difference is about 10%. 

Can women use Ostarine?

Yes, like MK-677, Ostarine can be used by women. However, remember not to exceed the dose of 10mg/day. At such a dose, the only side effects may be acne and increased libido. In case of higher doses, there may be a problem with lowering the voice. 

Ostarine vs. LGD-4033

Both of these substances are excellent for both reduction and bulking. LGD-4033 is a stronger SARM in this compilation and is therefore better suited for solo cycles. The advantage of Ostarin is that it does not cause significant testosterone suppression even during long cycles, as is the case with LGD-4033. 

RAD140 vs. Ostarine

RAD-140 significantly outperforms Ostarine in anabolic aspect – it is much better for bulking, even solo. On the other hand, Ostarin can be used for a long time without any side effects. This feature, combined with the ability to keep muscles during a calorie shortage, makes it much better suited for reduction. 

Ostarine half-life

The half-life of MK-2866 is about 24 hours. However, it is worth remembering that the metabolites of Ostarin can be detected in blood tests for about one month after discontinuation. 

Does Ostarine cause hair loss? 

No. MK-2866 is a very mild SARM. Neither studies nor user reviews indicate an increase in the amount of hair loss. If you notice such a symptom in yourself, it is most likely the result of a change in diet or stress associated with a higher workout load on your body. 

Does Ostarine cause cancer? 

Current research and user reviews do not give any indication that MK-2866 may cause cancer. 

Is Ostarine and a steroid? 

No, as we explained at the beginning of this article, MK-2866 belongs to the SARM group (Selective Androgen Receptor Modulators).

Is Ostarine legal?

Yes, Mk-2866 at the time of writing this article is legal in most countries of the world – including USA. However, please note that the substance is on the WADA list and therefore professionals taking part in competitions cannot use it.