Cardarine Side Effects

By: Juice

Last updated: is intended for informational purposes only and does not take the place of professional medical advice.

Cardarine sounds like the perfect fat burning compound at first glance. It’s not a stimulant, so you don’t get those jittery effects that come with other fat burners.

Cardarine Side Effects
Cardarine Side Effects

The side effects seem to be minimal. It significantly boosts endurance and influencing the metabolism to efficiently promote fat burning. So what is there to worry about with Cardarine? Is this something you can use with zero concerns about your health?

The good news is that Cardarine has been put through a few studies and trials. The bad news is that the results weren’t all that great for our peace of mind.

While countless people do continue to use Cardarine, there are underlying risks that we all need to be aware of before deciding to use what is otherwise clearly a very effective fat burning and performance enhancing compound.

Author’s Note: The following guide is based on my personal experience and does NOT promote the illegal use of SARMs.

What is Cardarine (GW501516)

Cardarine is usually lumped into the SARM category of substances, but technically it is a PPAR receptor agonist. This class of drugs is designed to treat metabolic syndrome symptoms by lowering blood sugar and triglycerides (fat lipids in the blood).

Cardarine GW-501516 Structure
Cardarine GW-501516 Structure

Cardarine was originally also researched as a possible treatment for cardiovascular related medical problems. This tell us a bit about what Cardarine might be useful for in the world of bodybuilding and athletics.

At its core, Cardarine is very powerful in two main areas: endurance and fat loss. The endurance benefits of Cardarine were essentially accidentally found during research of the drug, and this is what athletes caught on to.

Could Cardarine really be so powerful as to power your cardio workouts to a level similar to some steroids, but without those familiar steroid side effects? It didn’t take long for the athletic and bodybuilding world to start getting a hold of, and using Cardarine for exactly these purposes.

Cardarine has plenty of other names as well: GW-501516, GW1516, GSK-516 and Endurobol. So if you see any of those terms being used, you know it all refers to Cardarine.

This compound has actually been around since the early 1990’s but due to some unfortunate research at extremely high doses about 15 years later, and the associated findings of this, the large pharmaceutical company that originally had interest in Cardarine ceased all further study.

Now it’s mainly of interest to those wanting its performance effects. Cardarine’s users go well beyond just bodybuilding though, with anyone involved in endurance and cardio intensive activities and sports finding it beneficial.

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What does Cardarine do?

There are three primary benefits of Cardarine which all work together to make this a prime cutting compound: fat burning, endurance, and nutrient efficiency.

Cardarine Benefits
Cardarine Benefits

It’s also valued by performance athletes who don’t necessarily want to lose much fat, but are more concerned about the performance enhancing effects of Cardarine. In fact, above all else it’s Cardarine’s massive boost to endurance that’s considered by many of us to be its most powerful benefit.

That means to get the most from what Cardarine can do, you need to be prepared to work hard. No point having that massive endurance and performance boost if you’re not going to use it. Those who are determined to raise to the next level will find training sessions can be longer, more intense, and that means faster and more extreme Cardarine results.

Plenty of people use Cardarine with fat loss as the primary goal. While Cardarine doesn’t directly as a stimulant to the nervous system, the flow on effects from its cardiovascular and nutrient efficiency benefits all lead to fat burning being much easier and faster – provided you’re working out and eat properly.

The nutrient efficiency effects of Cardarine is a valuable benefit because you’ll be getting the maximum from every nutrient consumed. If losing fat is the goal, getting the most from a calorie deficient diet is critical if you’re going to be able maintain a consistent high level of training without becoming fatigued.

Cardarine is good at boosting the amount of glycogen that’s stored in the muscles. So although it’s definitely not a bulking compound, some users notice extra muscle fullness which is a nice bonus benefit.

With less fluid in the cells, muscle definition can be improved and you may see a nice vascularity gain. This will depend on your diet and goals, but these benefits are especially attractive to fitness models or competitors, rather than sports athletes.

One of the flow on benefits of Cardarine is how it affects cholesterol. If you’re a steroid user then you would be used to cholesterol taking a big hit with most steroids, and indeed many SARMs as well. Cardarine is the opposite – it very likely benefits your cholesterol levels by lowering LDL cholesterol and increasing HDL levels.

So while this might not be a high priority for you when using Cardarine on its own, it does provide an option for stacking with cholesterol raising steroids where it can act as a risk lowering compound, especially for anyone with existing cholesterol problems.

For other reasons Cardarine can be a useful companion to certain other steroids as well, in particular Trenbolone. Tren is famous for impairing cardiovascular endurance and bringing about breathing difficulty in some users.

By stacking Cardarine with Trenbolone, you can partially or fully alleviate that debilitating side effect so your workouts on Trenbolone can be at your full potential.

Unfortunately there is a potential risk when stacking Cardarine with many steroids and SARMs, and this involves the liver as I will outline further below.

One of the big questions new users of Cardarine will have is – what happens when you stop a Cardarine cycle?

Specifically, can you expect to maintain some improved cardiovascular performance and endurance after a cycle, or does it come to a halt. This will be an individual response, but people do find an ongoing improvement in the weeks following a cycle, which is to be expected.

It is possible that, when you continue to engage in high intensity workouts, that the heart’s natural muscle memory and capacity for endurance will have improved. But once you stop high intensity workouts, you can expect overall endurance to decrease without Cardarine.

Finally, the benefits of Cardarine should also include the simple fact that you don’t suffer with the debilitating side effects of steroids and many SARMs. This means no testosterone suppression at all, so no PCT is needed if using Cardarine alone.

Cardarine can be used by women just as beneficially as it is by men. No virilizing effects can occur as it is not a hormonal compound. Many women effectively use Cardarine for fat loss as an alternative to steroids and SARMs.

Short-Term Side Effects

There are few known short term side effects of Cardarine. This would be one of the most side effect friendly compounds out there, and using it at recommended doses will see most people generally free of side effects.

This is not a steroid and has no steroid like properties, so there’s no androgenic or estrogenic effects to worry about. This is one of the most appealing things about using Cardarine for fat loss and shredding: you don’t suffer with any water retention.

In fact Cardarine can decrease the level of fluid in the cells and actually promote a more defined and vascular physique for those on a SARMs cutting cycle.

As with any substance, people will have different responses and you will hear about varying short term side effects. One of those is insomnia, or difficulty in falling asleep. Other reported temporary side effects include headache and fatigue.

Most individuals who are unlucky enough to suffer with these side effects note that it happens during the first stages of the cycle, and usually subside after a short time.

Long-Term Side Effects

The offending study that led to discontinuing research on Cardarine involved mice who were given very high doses of Cardarine. Although physical performance of the mice was considered considerably enhanced, they rapidly developed cancers in several organs at these very high doses. As a result, Cardarine was not deemed safe for further research with humans.

Naturally, any time the word cancer appears it requires taking a step back and considering whether a substance is high risk. Yes, the study used doses that are well beyond what we would ever consider using, but the risk of cancer still needs to be considered as a potential risk factor for Cardarine.

Aside from this, there is no data about any other long term health risks or side effects from Cardarine based on current knowledge. Avoiding high doses is key to reducing risk as much as possible.

Hepatotoxic Side Effects (Liver Toxicity)

Cardarine is not known to cause any toxicity to the liver. Minor changes to liver values were recorded during some of the trials.

While once again we need a lot more research to find out exactly what, if any, impacts Cardarine does have on the liver there’s a possibility people with existing liver conditions could be vulnerable to more dangerous fluctuations in liver enzyme values.

So if you have an existing liver condition you might want to rethink using Cardarine at all at this point in time, until more is known.

It goes without saying that consuming alcohol or many types of prescription medications (especially anti-depressants) while using Cardarine is strongly advised against, and the effects on the liver of doing so is unknown.

There is a circumstance where Cardarine can pose a greater risk to your liver. That is when you stack it with one or more other compounds like steroids or SARMs.

Cardarine promotes cellular proliferation (cell growth and cell division), so other compounds which themselves have negative impacts on the liver could see this serious side effect multiplied and worsened when combined with Cardarine.

This will bring about a significant change in liver enzyme values for the worst, and in extreme cases could lead to liver failure. There is no research available to show exactly how Cardarine could intensify liver toxicity, so if you’re determined to stack Cardarine with liver stressing compounds, try and stick to the shortest possible cycle to reduce this risk.


The most concerning find to date has been the cancer development in mice during a trial many years ago. Again it needs to be emphasized that excessive doses were used and as far as anyone knows to date, it is the very high dose of Cardarine that resulted in cancer development.

Could this potentially happen in humans who repeatedly used lower doses of Cardarine? We simply won’t know without any proper studies. The fact that Cardarine does clearly have some activity that results in cancer formation, even if only at excess doses, makes it a compound that many will think twice about using.

Most people will use Cardarine for around 8 weeks at a time, and take a break in between cycles (ideally). This is a big difference from a 2 year, high dose cycle as was undertaken in the research.

Put it this way: any medication that resulted in cancer the way Cardarine did in its study would be extremely unlikely to ever be approved for human use. This means Cardarine is unlikely to ever see FDA approval, whether or not this cancer risk is a factor at lower doses and shorter term use.


It’s not uncommon for Cardarine users to report difficulty sleeping, especially towards the beginning of the cycle. But as Cardarine isn’t a stimulant, despite its powerful fat burning and energy inducing effects, it would not have the same impact on sleep and rest as a potent stimulant drug would have.

So what could possible cause insomnia and sleep difficulties in some Cardarine users? There’s no research indicating insomnia should be a side effect, so it’s very likely a personal response between each individual.

Certainly most people who use Cardarine aren’t suffering with insomnia. One possible solution that has worked for some people is to take your dose first thing in the morning.

Although Cardarine isn’t known for causing the highs and lows associated with stimulant substances and energy levels should be relatively stable throughout the day regardless of when you take your dose.

If you are experiencing insomnia related side effects, some users find that taking a zinc and magnesium supplement before sleeping helps alleviate this problem.

Women Specific Side Effects

As Cardarine is not a steroid and has no steroid like properties, women won’t suffer with the virilizing and other side effects that come from compounds with androgenic activity. This means that females on Cardarine will have the same side effect risk profile as male users since this is not a hormonal compound and does not affect estrogen or testosterone.

There’s no worry about masculinization signs like voice deepening and hair growth. Most women who use Cardarine do so to lose fat, but it should be considered whether the steroid Anavar is actually a better option.

Anavar is known as one of the best female-friendly compounds, with minimal side effects. In fact, its side effect profile for women may be less risky than Cardarine when one considers the cancer related data on Cardarine.

Is Cardarine Safe?

Cardarine has been put through a few clinical trials and none of these trials have revealed side effects in the human participants. But with so few trials done to date, there’s nowhere near enough clinical data for it to be known whether there are going to be any new longer term health risks identified with Cardarine.

It is known that there could be a potential cancer risk with prolonged or high dose use of Cardarine, based on rodent studies. But much more data is needed to even begin to confirm whether this could also happen at low doses over the long term.

In other words, a lot more thorough research is required and that means using Cardarine still comes with possible and real risks to health and safety.

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Does Cardarine lower bad cholesterol?

Studies on rats has shown that Cardarine can not only lower LDL (bad) cholesterol, but also raise HDL (good) cholesterol at the same time. One study showed that Cardarine may decrease the risk of heart attack.

Does Cardarine hurt the liver?

People with good liver health who use Cardarine are not known to be at risk of liver damage. In fact it may even have some liver protective properties. However if you have an existing liver condition there’s some data that suggests some risks to the liver might be there and those with liver disease are advised not to use Cardarine.

Will Cardarine keep me up?

There are more than a few reports of people having trouble sleeping on Cardarine and even some with full blown insomnia.

It’s not known what causes this side effect in some users, but it is likely an individual response as there are many people who do not have any sleeping problems when using Cardarine.

Taking your dose in the morning can help alleviate the symptoms, while also considering supplements like magnesium and zinc.

Should I stack Cardarine?

While Cardarine has benefits when stacking it with some steroids or SARMs, it could also possibly cause stress to the liver due to the way it proliferates cells. This risk is not fully understood, so caution should be taken.

Despite this, people do commonly stack Cardarine with compounds like Ostarine for a more powerful cutting cycle, or with Ibutamoren MK-677 for increased muscle growth.

Is Cardarine illegal?

It is not legal to use Cardarine in any competitive events. It is listed as on the WADA Prohibited List in the category “S4 Hormone and Metabolic Modulators”.

My Conclusion and Recommendation

It’s easy to become complacent and just follow along using Cardarine because so many other people are doing it. But plenty of people do things that are known to be dangerous while ignoring the risks.

Cardarine still has a lot of question marks around it so you really are taking a large does of “hope” with it every time you use it. I was fine with this in the beginning but I’ve been seriously questioning my decision to buy Cardarine as time goes on.

Anything that comes with even a hint of a cancer risk is enough to steer me right away and unfortunately, despite Cardarine’s otherwise impressive effects and seemingly low side effect risk profile, it’s hard to get cancer out of your mind.

Is it worth the risk if you just use Cardarine at low doses and hope for the best? Not for me.

About the Author
Juice Lewis, Author of
Juice Lewis

Real-life Experience, not Theory

I don't claim to know everything; what I talk about here is something I've done. From anabolic steroids to HGH, to peptides, insulin, and supplements, I've done it at some point in my life, and I can relate.