Clenbuterol: Everything You Need To Know


If you’ve ever seen a bodybuilder or fitness model and wondered “how are they so lean?”, 9 out of 10 times the answer is simple:


And when it comes to fat burning drugs, Clenbuterol is the undisputed king.

Although originally developed for reasons that have nothing to do with physical fitness, it didn’t take long for bodybuilders and athletes to figure out the physique-transforming potential of Clen.

If you go to a real gym (not planet fitness), chances are somebody there is either on Clenbuterol or has experimented with it in the past.

Whether they’re willing to admit is another story, but it’s basically impossible to drop below 5% body fat without some “help” (if you catch my drift).

So yeah, that guy with the 10 pack whose veins have veins could very well be using Clenbuterol (or something like it).

But is it really worth it?

Like all drugs, Clenbuterol may be effective but it does come with risks and potential side effects that you be aware of before experimenting with it.

Not to worry though…

By the end of this article, you’ll know everything you need to know about Clenbuterol, including:

  • What It Is
  • How It Works
  • Why People Use it
  • The Benefits
  • Side Effects
  • Legality
  • Where To Buy It
  • Alternatives (Supplements)

The last thing I want to do is tell you what to put inside your own body.  It’s yours.  Do what you want.

My goal is simply to lay out the facts–based on actual science–so that you can make an informed, educated decision in the end.

Sound fair?  Okay, let’s get started then.

What Is Clenbuterol? How Does It Work?

Pills of Clenbuterol

Clenbuterol was originally developed as a bronchodilator (to treat respiratory issues like asthma) in animals, namely horses.

It works by relaxing the muscles surrounding air ways, making it easier to breathe when there is some sort of air way obstruction.

Clen is available world-wide, sold under brand names such as:

  • Dilaterol
  • Spiropent
  • Ventipulmin

It can also be found in many generic products as well and is readily available from research chemical vendors in the US and abroad.

We’ll get into the legality and how to buy Clenbuterol a little later.

First, let’s discuss how exactly it works, from a fat-burning perspective…

Clenbuterol is a beta-2 adrenergic receptor agonist, meaning it binds to (and activates) beta-receptors.  

These receptors work side by side with alpha-receptors to regulate the process of lipolysis (fat-breakdown).

Put simply, beta-receptors initiate Lipolysis and alpha receptors put a stop to it.

By agonizing (activating) beta-2-receptors, Clenbuterol directly stimulates lipolysis and increases the metabolic rate.

It is hands down one of the most powerful, effective fat-burning drugs of all time, even though it wasn’t originally intended to do anything related to fat-loss at all.

Why Do People Use Clenbuterol?

Clenbuterol Bottle

As a bronchodilator, Clenbuterol is a prescription medication in several countries.

But let’s face it…

That’s not why you’re intersted in Clen.

So let’s just cut to the chase, shall we?

There are two primary reasons why people–particularly in the fitness community–use Clenbuterol.

  1. To Burn Fat
  2. To Enhance Athletic Performance

Due the fact that it’s a potent (possibly the MOST potent) beta-2-receptor agonist, there’s really no doubt about the fact that Clenbuterol burns fat.

However, there does exist some debate as to whether it can actually enhance physical performance.

When used as prescribed–the inhaled/vaporized form–research suggests it’s probably not an effective performance enhancer.

In fact, preliminary (rodent) research indicates that chronic use of Clen may actually hinder physical abilities.

Of course, it’s possible that in the short-term, Clenbuterol enhances physical abilities, but the effects fade with prolonged use.

This is fairly common with beta-2-receptor agonists which tend to have a desensitizing effect when used for too long.

In other words, prolonged use can result in tolerance build-up.

This is why, even in the bodybuilding community, it’s ill-advised to take Clenbuterol for more than 4-8 weeks.

Well, that and the fact that long-term abuse of Clen comes with a fairly long list of potential side effects and health issues.

More on those later, though.  First, let’s talk benefits.

What Are The Benefits of Clenbuterol?

Ripped Guy On Clenbuterol

Clenbuterol burns fat faster than would otherwise normally be possible.

Just to reiterate, it does this by up-regulating beta-2-receptors, a well-established mechanism for fat-loss, which it shares with Higenamine, Ephedrine, and Synephrine.

Perhaps the most intriguing aspect of Clenbuterol, however, is that it has developed a reputation as a muscle-builder as well.

If this is true, it would mean it’s one of the few non-steroidal fat-burning compounds that also builds muscle.

But is there any truth to this?

While there is some evidence that Clen can increase strength and lean (muscle) mass, so far, muscle-building/sparing effects have only been noted in subjects with some kind of health issues characterized by muscle-loss.

Clenbuterol has been shown to increase muscle protein synthesis, but it’s long-term ability to build muscle remains questionable.

It would appear as though any performance or muscle-building effects are mediated by beta-2-receptor agonism.

In other words…

Clenbuterol may enhance performance to some degree early on which could potentially increase muscle mass, but in the long-term, it doesn’t really have any muscle-building mechanisms.

You may go harder in the gym, causing you to make greater gains in a shorter amount of time, but the same can be said for other beta-2-receptor agonists or stimulants in general.

Anything that activates (or acts like) Epinephrine (Adrenaline) has inherent fat-burning effects and can potentially enhance performance in the short term.

So, it stands to reason that Clenbuterol can as well.

That said, the notion that Clen can build muscle while burning fat is a little bit of a stretch.  It can definitely burn fat and won’t necessarily cause muscle-loss, but that’s not the same thing as building muscle.

What Kind Of Results Can You Expect With Clenbuterol?

Clenbuterol Results

You can definitely expect to lose body fat and get leaner in a pretty short amount of time.

When you see those bodybuilders and fitness models that are so lean (like 3-5% body fat) and you’re like

“how the heck do they get so lean?!”


Clenbuterol will do that do you.

However, as it has risen to the top of the bodybuilding and fitness community as one of the best fat-burning drugs of all time, practicality has kind of been swept under the rug.

The truth is, the magnitude of the metabolic rate increase seen with Clenbuterol remains under-researched.

If you take a look at the studies on Ephedrine–which functions as a beta-2-receptor agonist as well, same as Clenbuterol–a 5% increase in metabolic rate is average, resulting in fat-loss to the tune of about 1-2 pounds per month.

While actual studies measuring the metabolic rate increase with Clenbuterol are non-existent, anecdotal evidence suggests it can boost the metabolic rate by around 10% on average.

What does that mean?  Think of it like this…

If you take in 2500 calories per day, and Clen raises your metabolic rate by 10%, you’ll burn an additional 250 calories of fat per day.

Since you need to burn 3500 calories (of fat) to lose a pound of fat, you can expect to lose a pound of fat every 14 days.

That is, assuming your diet and exercise remains constant…

What we’re not taking into account here is the fact that Clenbuterol is known to suppress appetite–further reducing calorie intake–and may make you go harder in the gym (burn more calories during training).

So, while 250 calories/day seems pretty negligible, a well-designed Clen cycle can easily result in far more fat-loss than just 1 pound of fat every 14 days.

Clenbuterol Dosage

There is no precise clinical dosage for Clenbuterol.  It’s more of a range.

The first thing you need to understand is that Clenbuterol is dosed in micrograms (mcg).  Not milligrams.

If you accidentally dose your Clenbuterol in milligrams, you’ll surely regret it.

A typical starting dosage is 20mcg, but some people go as high as 100-200mcg.  Sometimes more!

It’s important to start with a low dose (like 20mcg) before deciding whether or not to increase the dose.

Many Clenbuterol dosing protocols call for starting at 20mcg and gradually increasing the dose by 20mcg at a time until you reach a maximum of 100mcg.

Women will typically require a lower dose than men, 20mcg is the recommended starting point regardless of gender.

Trust me, you don’t want to accidentally take too much Clen!

Clenbuterol Side Effects

Clenbuterol Side Effects

That’s the thing…

The reason Clenbuterol is approved for animals and not humans in the US, despite showing potent bronchodilator effects, is that it comes with a fairly long list of potential side effects.

The most common side effects from Clenbuterol are:

  • Heart Palpitations
  • Insomnia
  • Hypertension (High Blood Pressure)
  • Rapid Heart Rate
  • Anxiety
  • Jitters
  • Nausea
  • Headaches
  • Muscle Cramps

Clenbuterol has been shown to deplete Taurine and Potassium levels which would explain muscle cramping as a fairly common side effect.

Of course, this can be fairly easily remedied by supplementing with Taurine and Potassium.

The side effects listed above are relatively minor and millions of people have used Clenbuterol while experiencing minimal side effects.

Still, you have to wonder…

If Clenbuterol is an effective bronchodilator, why isn’t it prescribed to humans instead of just animals?

Well, in some countries it is.

In the US, however, Clenbuterol is not approved for treating breathing disorders in humans, nor for weight-loss.

Oddly enough, it’s only approved for horses.

That’s because the (US) FDA has deemed it dangerous and there are other bronchodilators (like Albuterol) which are much safer and more effective.

Although no deaths have been directly tied to Clenbuterol use alone, there is evidence to suggest that it can be lethal if used for too long and at high enough doses.

So, is Clen safe?

The bodybuilder at your gym will tell you “sure!” but your doctor will probably tell you “stay away!”.

Ultimately, whether the risks outweight the rewards is an individual choice, but make no mistake…

Clenbuterol comes with it’s fair share of potential side effects and health risks, especially those related to cardiovascular health.

Is Clenbuterol Bad For Your Heart?

Heart Health

Long-term studies on Clen in actual humans are virtually non-existent.  It’s been studied quite a bit in animals, but if you’re a regular reader of my articles, you know how I feel about animal studies.

If you’re not, let me just reiterate…

Just because something works (or causes harm) in animals, doesn’t mean it will have the same impact in humans.

That said, my personal stance is better safe than sorry.  If something appears toxic in lab rats, it could very well be toxic (at least to some degree) in humans.

For me, that’s enough to stay away.  If you want to roll the dice though, go right ahead!

What does the research say?

There is some preliminary evidence to suggest that long-term Clenbuterol use can be damaging to the heart.

In humans, 60 days of Clenbuterol was found to offer protection against exercise-induced asthma without any significant changes in cardiovascular function.

At this time, there are no long-term human studies pertaining to Clenbuterol and cardiovascular health specifically, but like most stimulants, it’s probably not a good idea to use it for long periods of time.

That’s why the average Clen cycle is 4-8 weeks at most.  Anymore than that and you’re in uncharted territory as far as studies are concerned.

Is Clenbuterol Legal?

Clenbuterol Legality

The short answer is:


But it’s a little more complicated than that…

Unless you’re a horse with asthma, you won’t get a prescription for Clenbuterol from any doctor (or veterinarian actually).  It’s literally only approved in the US as a drug for horses.

That said, it remains unscheduled under federal law which means it can be “sold without professional supervision” (AKA a prescription), just  not for the purposes of human consumption.

That may seem confusing…

Because it is.

You see, unscheduled drugs are commonly sold as research chemicals, the idea being that they’re “not for human consumption and are for research purposes only”.

You’ll find these types of drugs all over the internet and Clenbuterol is no exception.

Obviously this is just a legal gray area. 99.9% of the research chemicals (Clen included) are not being bought for research purposes are are indeed being consumed by humans.

Don’t you just love America?!

Where To Buy Clenbuterol

Buy Clenbuterol

There are a ton of research chemical websites that sell Clenbuterol.  The tricky part is finding one that you can actually trust.

The truth is most of these drugs come from China (just like everything else we buy), but the issue is that Chinese chemical manufacturers aren’t subject to the same types of strict regulations that chemical  manufacturers in the US are.

That’s why everything is so much cheaper in China and why most US companies outsource manufacturing of chemicals to China.

They’re able to dodge a ton of expenses due to the lack of regulations, allowing them to offer goods, services, and labor for much lower prices than heavily regulated countries like the US.

So, even if you order Clenbuterol from a vendor who claims the product was “made in the US”, the actual ingredients are still from China.

“Assembled in the US” would be more appropriate.

That doesn’t mean you shouldn’t trust it anymore than you shouldn’t trust your laptop, tires, or plastic cups.

What’s important is buying from a company that you trust.

I’ve heard good things about CEM Products but since I’ve never personally tried Clenbuterol (the risks outweight the rewards for me), I really can’t vouch for any particular supplier.

Google around, hit up Reddit, and ask around on Forums.  Do your homework, especially when it comes to Clen.

Clenbuterol Supplement Alternatives

Supplement Alternatives To Clebuterol

There’s no denying that Clenbuterol burns fat, but the fact is that it’s difficult to obtain from a trusted source and the potential risks may outweigh the benefits for some people.

Fortunately, there are some legal (supplement) alternatives to consider.

Of course, no supplement is going to be as powerful as a drug that does the same thing (but better), but there are definitely some that can help.

Considering they’re entirely legal, some of these supplements are pretty powerful (especially when stacked).  They’re also a lot safer than taking drugs with a tenuous safety profile.


Higenamine is definitely the closest thing to Clenbuterol that’s legally sold and bought as a supplement.  It works exactly the same way:

Beta-2-Receptor Agonism.

To re-cap, this means Higenamine is capable of directly stimulating Lipolysis and increasing the amount of fat you burn.

It’s found in several plant species which is why it can be used in dietary supplements, but I wouldn’t be doing my job if I didn’t make it clear that:

Higenamine Is Not As Effective As Clenbuterol.

But of course, that comes with a silver lining…

It’s also a lot safer!

While Clenbuterol has a ton of adverse health consequences tied to it, Higenamine is safe (when used appropriately of course).

Caffeine and Yohimbine (or Rauwolscine) may amplify the fat-burning effects of Higenamine.


Rauwolscine is a stereoisomer of Yohimbine, meaning they are extremely similar in terms of chemical structure.  In fact, they function exactly the same way:

Alpha-Receptor Antagonism.

Remember how we discussed the two major types of receptors that regulate fat-loss?

  1. Beta-receptor
  2. Alpha-receptors

While Clenbuterol and Higenamine activate beta-receptors, directly stimulating fat-loss, alpha-receptors put a stop to fat-loss.

So, by antagonizing (blocking) the action of these receptors, Rauwolscine allows fat-burning to continue.

The result?

You’ll burn more fat in a given amount of time than you normally would with Rauwolscine.  The more you workout with it, the more fat you’ll burn.


Synephrine, like Higenamine, is a beta-receptor agonist which is often consider “the weaker form of Ephedrine”.  That’s definitely true to an extent.

Synephrine does the same thing as Higenamine, Clenbuterol, and Ephedrine, but is much more mild.

The good news?

Side effects are VERY rare with Synephrine.  In fact, a lot of people just stack Synephrine with something stronger to add a slight edge.

On it’s own, Synephrine is not what you would call a highly effective fat-burner.

Combined with some Rauwolscine and Caffeine though…

Now you’re talking serious fat-loss.

Which begs the question…

Is Clenbuterol really worth it?

If there are adjustments you can make to your diet, workout style/schedule, and lifestyle–not to mention a few supplements that can lend a helping hand–shouldn’t you worry about those first before resorting to Clen?

My Personal Opinion On Clenbuterol

My opinion on Clenbuterol for losing fat

I don’t think Clen is worth it, to be completely honest.

I know a lot of people that have used it but I’m leaner than most of them and I have used ZERO clen in my lifetime.

Clen isn’t some miracle weight-loss drug that just melts fat off your body.  It can help you lose a few extra pounds a month, but so can:

  • changing your diet
  • exercising more or more intensely
  • taking a well designed, safe supplement stack

If you’re goal is fat-loss, I’d suggest making changes in those areas before considering any kind of drug.

As I mentioned in my articles on Focalin and Etizolam, I’m no stranger to recreational drug use, but with Clen I feel the risks/side effects outweigh the rewards.

You’d be surprised how much leaner you can get naturally (without drugs) by making a few simple changes to your diet and exercise.  

There’s just no need to use drugs like Clenbuterol for the average person who wants to be fit and healthy.

The Bottom Line On Clenbuterol

The Bottom Line On Clenbuterol

When it comes to fat-burning drugs, nothing tops Clenbuterol.  There’s no doubt about it…

This stuff burns fat!

As with all drugs, however, there are risks to be considered.

If you’re having trouble getting lean, drugs shouldn’t be your first-line solution.

It’s possible to get super shredded without drugs, but the allure of fast fat-loss is enough to make some people say screw it and ignore the risks.

Well, that’s ultimately your choice I suppose.

The truth is if you

  • Eat Lean (Slightly Caloric Deficit/High Protein)
  • Lift Smart (Heavy Weight Lifting/HIIT for Cardio)
  • Rest (Sleep/Off-Days)
  • Supplement Smart (Clinical Doses Of Supplements That Work)

You can get pretty damn lean.

Before you turn to drugs of any kind, make sure you have your bases covered.  You may be quite surprised with just how lean you can get naturally (without drugs).

Did I miss anything?  Do you have any experience with Clenbuterol?  Anything you’d like to add?  Comment below…

I’m Matt Theis, founder of SuppWithThat, Momentum Nutrition, and Singular Sport. I created SWT to separate the science from the hype and publish accurate, research-based information on supplements. If you like what I have to say here, feel free to check out my supplements at and

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