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Ostarine (MK 2866): Dosage, Results, Side Effects, and More

Also known as:Enobosarm, MK 2866, GTx-024
Dosage:25mg a day
Good for:First time sarm users and cutting cycles.
Legal status:Legal in the USA for research purposes only.
Stacks well with:Cardarine (cutting), MK 677 (bulking)
Common side effects:Temporary suppression of testosterone levels.

Ostarine, also known as MK 2866, is one of the most popular SARMs available. It has a very strong anabolic effect, and can be used for both bulking and cutting.

Originally, ostarine was created by GTx to treat muscle wasting disorders such as cachexia. Nowadays many people (myself included) use it for it’s performance enhancing properties.

In this article, I am going to discuss benefits, side effects, dosages, cycle examples, before and after pictures, and more. By the end of this article, you will have everything you need to know about ostarine.

If you are still unsure about anything, feel free to write in the comments section below and I’ll get back to you ASAP!

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4 Benefits of MK 2866

It’s Extremely Mild

Side effects from sarms can put a big damper on your training.

Luckily, ostarine is extremely mild and well tolerated by those who use it. It is very uncommon to experience side effects while on cycle.

Multiple studies demonstrate it’s high safety profile and efficacy.


MK 2866 can be used to bulk, cut, or even recomp depending on your goals and diet.

Because it’s so mild, you can stack it with other compounds to improve your overall results.

Ostarine works best on a cutting cycle, especially stacked with cardarine or andarine.

Safe for Women

Ostarine is safe for women since it is not androgenic in any way. Women should use a lower dosage (10mg a day) to prevent potential side effects.

I have many female friends who compete in local bodybuilding shows. Pretty much all of them are taking some sort of SARM. More and more women are ditching steroids like Anavar in favor for sarms.

Impressive Physique Changes

The physique changes you can achieve from running an eight week cycle are nothing short of mind blowing.

Expect dry, vascular gains while on cycle. Even with no change in diet, ostarine has the ability to radically improve your overall athletic condition.

This study is a great example of the anabolic effect ostarine has on the body.

A powerlifting using ostarine to improve his performance.

Top 3 Results To Expect

As I mentioned above, Ostarine causes some incredible changes in your body when taken. I am going to mainly focus on the physical results since that’s what most of my readers care about.

If you’re interested in some of the other health benefits of sarms, you can refer to this study.

Muscle Growth

It’s not a secret that SARMs can help you build large amounts of muscle. Ostarine is no different.

During an 8 week cycle of Ostarine, you can expect to gain around 7-10lbs of lean body mass.

This study shows that even after subjects stopped taking ostarine, they continued to retain muscle mass gained from the cycle.

Bottom line? MK-2866 makes it easy to achieve long lasting gains in the gym.

Fat Loss

Although not a direct aide to thermogenesis, Ostarine can help promote fat oxidation in humans.

Users who are in a caloric deficit will experience much better muscle retention compared to natural lifters.

In addition, it has been proven that increasing muscle mass will increase TDEE (how many calories you need a day to stay the same weight). When you gain muscle, your body will naturally burn more fat as energy in order to keep that muscle.

Strength Gains

Ostarine especially shines when combined with strength training, and users consistently report strength gains similar to those found in anabolic steroids.

In fact, it is not uncommon to add 30lbs or more to your one rep max for bench press or squats.

For this reason, MK 2866 is a very popular choice with athletes who want to increase their performance on the field or court.

Ostarine Before and After Pictures

We’ve collected some pictures that show before and after results.

As you can see from the pictures, ostarine is a very potent SARM that can give some impressive drops in body fat but also pack on some muscle as well.

before and after ostarine
before after ostarine results

Results like the ones above are not uncommon when using this compound. Of course, your mileage may vary depending on how well you keep your diet and routine in check.

Make sure to keep your protein intake high and you’ll have no issues achieving your goals.

Side Effects and Safety

One of the main concerns people tend to have when adding any sort of performance enhancer to their lives is what type of side effects to expect.

Luckily, ostarine has very little side effects to deal with. With that being said, there will always be some rare occasions of people experiencing side effects, and we wouldn’t be doing our jobs if we didn’t talk about them.


I’ve only seen this happen in one case, and it may not be due to using SARMs. This user reported feeling depressed around a week after starting ostarine.

In my opinion, this could be caused by a slight dip in testosterone levels, or it could just be a placebo. Worth noing, nonetheless.

Ostarine = Hair Loss?

Hair loss from sarms ONLY occurs in people who already have male pattern baldness. If your hairline is fine, this does not apply to you.

This user on the AnabolicMinds forum reported hair shedding on ostarine, but also mentioned in a later post that it reversed after stopping use.

I find is suspicious that it caused hair loss, since it is not androgenic in nature. It is very possible that this user received a fake product (that contained prohormones) and that is what caused the shedding.

You can avoid buying fake sarms by shopping with one of these sources.


Some people with naturally low testosterone might experience some lethargy while on cycle. This is because sarms slightly suppress your body’s natural production of testosterone.

The good news is that your body will naturally fix the imbalance within a month after you stop taking it. Studies show it takes around 5 weeks to completely recover.

Note: The above study was completed using LGD 4033

With that being said, if you have been diagnosed with low T you might want to consider getting on TRT prior to starting a cycle.

Woman using ostarine to improve her bodyweight fitness routine.

Dosage Guide

Follow these guidelines when deciding how much MK 2866 to use in your next cycle:

  1. Start low and work your way up
  2. Increase dosage every few days
  3. Cutting cycles generally require a smaller dose than bulking

With those key points in mind, lets jump into a few sample dosage guides.

Dosage For Bulking

Bulking on ostarine will require a slightly higher dosage than cutting, for the reasons outlined above. It takes a higher dose to create muscle than it does to retain it.

For those reasons, I recommend 25mg a day for anyone weighing over 185lbs. For those weighing less, you should give 20mg a day a try and see how you react.

Like I mentioned above, you should with a lower dose and work up. If you plan on doing a 25mg a day dose, I recommend working up like this:

  • 10mg for week 1
  • 20mg for week 2
  • 25mg for week 3 and beyond

If you respond well, you can skip the ramp up period for the next time you cycle MK2866.

For bulking cycles, I wouldn’t advise a cycle lasting longer than 12 weeks.

Dosage For Cutting

Using MK2866 for a cutting cycle will require a smaller dosage than a bulk. Retaining muscle mass while in a deficit is easy to achieve with smaller doses. You’re also less likely to experience side effects.

I recommend no more than 20mg a day while cutting.

Start at 10mg a day for your first week, and increase to 20mg for week two and beyond.

Cutting cycles should not last any longer than 12 weeks in order to prevent suppression.

Half Life

The half life of ostarine is 24 hours. This means that you can dose once per day with no issues in peak blood plasma levels.

I advocate for splitting doses between morning and night (or every 12 hours) in order to keep levels the most steady.

Some people also enjoy dosing pre-workout, however studies haven’t shown any noticeable difference.

Ostarine Liquid vs Capsules

I prefer liquid solutions for the following reasons:

  • Creating accurately dosed capsules requires expensive equipment that most labs don’t have.
  • Capsules force you to take full days dose at once, so you can not split between AM and PM like you can with liquids.
  • Liquids store well and can be taken sublingual to increase effects.

Where to Buy

If you want to buy ostarine online, there are a few things you should know before you place an order.

First of all, there are a ton of fakes out there. We have reviewed over 20 different sarm suppliers, and found than over 75% of them provided either fake or under dosed products.

One of the most common things I see are suppliers who ship out solutions containing prohormones such as superdrol.

These prohormones are dangerous, can cause side effects like gyno, and will shut you down hard. Do not gamble with what you put into your body.

There are a handful of companies that we can vouch for. Refer to this list and choose a company from the “recommended sources” section.

Use During PCT

One of the more interesting ways to use this compound is to actually take it during your post cycle therapy. Since MK-2866 is so mild, it can in theory be used to retain muscle mass while coming off of other anabolics such as testosterone.

If you plan on doing this, you must know two things:

  • The benefits of using sarms during PCT are hypothetical at best.
  • Only use low doses, something like 10mg a day max.

Depending on who you listen to, you will find mixed reviews on using it for this purpose.


How to take ostarine liquid?

You can take the liquid by simply measuring out the correct dose with an oral syringe, and squirting it into your mouth. Rinse down with water or juice. You may also take it under the tongue and let it sit there for 1 minute before swallowing. Ostarine liquid is NOT for injection. It is an oral solution.

When does ostarine kick in?

It should start working within one week. You will continue to feel it get stronger and stronger over the course of a month or so. By 30 days into your cycle, you will be in full beast mode.

How suppressive is ostarine?

It is actually one of the least suppressive sarms in existence. Blood work consistently shows that any reduced levels of testosterone are reversed within a month or two. This is one of the reasons it’s so popular.

How long does ostarine stay in your system?

I would recommend staying away from sarms if you are drug tested. However, if you plan on taking it anyways, allow a solid month to let it clear your system completely.

Do I need to do PCT after?

Usually not, depending on cycle length. If you plan on going the full 12 weeks, it might be a good idea to do 4 weeks of tamoxifen (Nolvadex) at 20mg for four weeks. You will not need anything stronger than that (stay away from Clomid).

What to stack with it?

A good option is always MK 677 to raise your HGH levels. You can also stack with S4 or even cardarine for an even more potent drying effect.

24 thoughts on “Ostarine (MK 2866): Dosage, Results, Side Effects, and More”

    • That depends on where you buy your Ostarine from. I know that proven peptides formulates theirs at 25mg per 1ml.

      Therefore, if you are using their formulation, you would need 0.4ml to equal 10mg.

      Last time I ordered from them they included a measuring pipette with the order, so it’s easy to measure.

  1. What do you recommend for a beginner who is 100 percent natty and never done steroid/sarms before.

    Been working out for 5 years have a good base with fat around the belly and thighs.


    • Ostarine or LGD4033 would be your best bets. If you want to lean up, I’d stack either one with Cardarine.

  2. Have you ever heard of bruising occurring while running Ostarine? I’ve run two cycles and during both at some decent sized bruises appeared on my triceps for one and on my forearm for the other, they were not a result of physical contact as far as I am aware.

  3. Can ostarine be absorbed through the skin if you don’t use it but are testing positive for it? Please email me. I am desperately trying to figure out why my son continues to test positive for this substance but has never used it? Could his body be making something similar to this and mimicking it on a test? Please I am desperately looking for answers.

    • I think the most likely scenario is that your son was using Ostarine. To answer your question, Ostarine has a molar mass of 389.33g/mol and anything under 500g/mol can be absorbed transdermally. With that being said it would be difficult to absorb enough to test positive by just coming in contact with it. The Ostarine would need to be applied via a carrier (Propelyne glycol, DMSO, etc) to effectively penetrate the skin.

  4. If i want to try a cycle on Ostarine let say 8 week and then I want to compete in Olympic lifting Nationals how long do i have to stop using it, in order to be negative on the test.

    • The rule of thumb is that 5 half lives will keep you in the clear. The half life of ostarine is roughly 24 hours, so that would be 5 days after your last dose. In an Olympic competition, they might be using more sensitive testing, so to be safe I’d give it at least 2 weeks.

  5. what about using the stack of Ostarine and MK677 do they clear up in 5 half lives also or they take more time to clear up in the system for purpose of testing

  6. When reading the answer to whether or not a PCT should be used after a cycle, it says usually not but for 12 weeks, yes. So what’s the cutoff length between a PCT being recommended or not needed? I am considering trying an 8 week cycle.

    • A PCT is never “necessary” per se. Even with heavy anabolic use, your body will always recover naturally via homeostasis. A proper post cycle therapy is useful to minimize the time it takes to kick start your HPTA system. Using a SERM like nolva, clomid, or torem are all popular options.

      It’s a fine line. Too much SERM: Improve recovery time, but with side effects. No SERM: longer recovery time but guaranteed no sides.

      The best way is just to use a small dose. For nolva, 10mg should be fine. Clomid is more than enough at 12.5mg. Many studies back this up and the only people who should be using 50mg+ are females who are trying to increase fertility.

      I will say that if you’re doing 8 weeks of nolva only you’re probably fine to skip the SERM. Bouncing back from Ostarine is super easy.

  7. I will start using the stack of MK-2866 and MK-677. 25ml per day on both during the morning time. I usually training 3 days a week and the off days of training should i using it or not?

    • Yes, you want to keep using it even on your days off. Steady levels of both in your system will do a lot of good for building muscle even when you are not training. Remember, you grow in between gym sessions, not during them!

  8. Hi thanks for the great content.

    How long should I wait after a cycle to start my nolva 10/20mg.
    For AAS I read wait at least a week but what would you do?

    • The whole “wait a week so everything clears” is largely broscience. The idea was that PCT won’t be effective until everything is out of your system (which is true), but the only logical reason to hold off on starting PCT is if you’re trying to prevent side effects from the PCT drugs. When this idea was first pushed on the community it was back in the day when people were taking 150mg of clomid a day. We now know that clomid is effective at even 10mg in men and does’t bring the same side effects. 10-20mg of nolva will not have many (if any at all) side effects either.

      With that being said, you’re good to go to start PCT the day your cycle ends. Some people like to start pre loading the nolva a few days before the cycle ends as well to allow it to build up in your system for when you come off. Either way works.

      Don’t overthink it, you’ll be fine regardless of which method you use 🙂 Good luck and thanks for the comment!

    • The only time someone will be tested for Ostarine is if they compete in sports at a high level. SARMs will not show up on any kind of employment, military, or court drug screen.


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