What is Clenbuterol? Side Effects and Health Review

Disclaimer: Clenbuterol is a controversial drug initially designed for animals. It is not approved for human use in the U.S. at this time. This article is not an endorsement for the drug and is meant for review purposes only.

Struggling with stubborn fat? Perhaps you’re trying to preserve lean mass while cutting? Clenbuterol can help, but this doesn’t mean it’s safe or good for you. 

This popular fat burner belongs to a class of drugs called beta(2) adrenergic agonists. It’s not a steroid but an asthma medication. Like many anabolic steroids, it helps preserve and build muscle while torching fat. 

In fact, Clenbuterol is so strong that it may cause cardiac hypertrophy and damage your heart. Research conducted on mice has found that it may increase the left ventricular mass in just three weeks. 

Traditionally, manufacturers used this drug as a bronchodilator and decongestant. It has been around for over four decades and possesses similar properties to salbutamol and epinephrine. However, its effects are stronger and longer-lasting. 

Bodybuilders, fitness models, and other athletes use Clenbuterol as part of cutting cycles, increasing the dosage gradually. Some take it a few weeks before competitions to lose stubborn fat and get ripped. 

As you would expect, people often abuse or misuse Clenbuterol is. Many newbies take the drug in an attempt to get leaner without being aware of its side effects. These can range from mild to severe and may include hypertension, tachycardia, palpitations, tremors, and even death. 

Clenbuterol side effects often outweigh the benefits. There are safer ways to lose fat and reach your training goals. Here’s what you should know about this drug so you can make an informed decision. 

What Is Clenbuterol? 

Few things are more frustrating than trying to lose those last few pounds. You eat clean and work out hard, and yet, you can’t get rid of belly fat. At some point, you might find yourself looking for alternative solutions, like Clenbuterol. 

This steroid-like drug was once used mostly by elite athletes. Today, it’s popular among dieters and gym-goers. Celebrities like Britney Spears and Victoria Beckham made headlines after losing weight thanks to it. 

From a chemical standpoint, Clenbuterol is a beta(2) agonist. After ingestion, it relaxes the smooth muscles that make up the walls of the airways within the bronchial tree. Approximately 89 to 98% of it is absorbed into the body, with a half-life of 36 to 39 hours. 

The drug is typically prescribed to humans or large mammals, such as horses. It may help relieve asthma and other respiratory problems, making breathing easier. In some countries, it’s used as a growth-promoting agent for pork, beef, poultry, and other animals, notes the United States Anti-Doping Agency (USADA). 

Its use in sports is prohibited because of its lipolytic and performance-enhancing effects. In fact, it’s classified as an anabolic agent, not as a beta (2) agonist, by the World Anti-Doping Association (WADA). 

Generally, athletes take Clenbuterol, or Clen, in pill form. The drug can be inhaled, but this form of administration diminishes its efficacy. A 2012 study published in Sports Medicine hasn’t found any improvements in strength, endurance, or sprint performance in athletes who inhaled beta(2) agonists. 

Note that Clenbuterol is not approved for human use in the U.S. It can only be used on horses. However, it’s available by prescription in other countries. 

So why isn’t it approved in the U.S.? Let’s discuss the concerns and side effects.

Clenbuterol Side Effects

While it’s true that Clenbuterol makes fat loss easier, its side effects can be life-threatening. Even small doses of the drug may cause adverse reactions. 

For example, this case study indicates that doses as low as 20 micrograms may affect electrolyte balance and cause toxicity. 

A 25-year-old man ended up at the ER after taking just one tablet (20 micrograms) of Clenbuterol. He admitted to having regularly taken the same dose for over three weeks without any side effects. 

His symptoms included sweating, increased heart rate, tremors, electrolyte imbalance, and cardiovascular instability. He required five days of hospitalization to recover. 

The effects of Clenbuterol kick in about 30 minutes after ingestion and peak after three hours. Some individuals may experience nausea and vomiting, convulsions, irregular heartbeat, tremors, convulsions, and chest pain after using the drug. 

In more severe cases, Clenbuterol may cause atrial fibrillation, myocardial ischemia, or even myocardial infarction. It can also reduce magnesium and potassium levels in the bloodstream while increasing blood sugar and phosphorus concentrations. 

According to another case report, this drug may cause myocardial damage. Fever, chills, dizziness, and headaches may occur too, states the Drug Enforcement Administration. Most symptoms subside within two to six days. 

Clen also affects potassium and taurine levels, which may cause cramping. That’s why many athletes use taurine supplements while on a Clenbuterol cycle. Other potential side effects may include:

These adverse reactions can affect anyone, regardless of age. A 2019 report, for example, describes the case of a healthy 22-year-old-college athlete who developed myocardial ischemia after taking the drug.

Why Athletes Use Clenbuterol

Clenbuterol gets a lot of praise for its ability to burn fat and preserve lean mass. However, it won’t work unless you’re already lean. 

Most athletes use this drug for weight loss. Like other beta(2) agonists, Clenbuterol raises heart rate and basal metabolic rate, causing your body to burn more calories throughout the day. 

Beta(2) agonists are the opposite of beta-blockers, which inhibit the release of noradrenalin and epinephrine (adrenalin). These catecholamines increase heart rate, blood pressure, and vasodilation. Adrenaline also opens the airways in your lungs, helping you breathe more easily. 

Clenbuterol stimulates the releases of noradrenalin and epinephrine, increasing core body temperature and resting metabolic rate. At the same time, it helps preserve lean mass and reduces muscle atrophy. 

A study conducted on patients with brachial plexus injuries suggests that Clenbuterol reduces muscle loss. As the researchers note, this compound may also increase lean mass and improve muscle function in those who are immobilized or suffering from muscular dystrophy. 

Furthermore, clinical evidence confirms its fat-burning effects, which appear to be greater than those of yohimbe and ephedrine. It may also have a small but positive impact on muscle growth and power output. 

Unfortunately, these potential benefits come at a price. When used in high doses, Clenbuterol may have life-threatening effects. 

How to Take Clenbuterol 

Many side effects of Clenbuterol arise from its misuse. The daily recommended dosage for asthma is 0.02 to 0.03 milligrams twice a day, according to the Drug Enforcement Administration. 

Athletes and dieters typically take incremental doses of 60 to 120 micrograms (0.06 to 0.12 milligrams) a day. Some go up to 720 micrograms (0.72 milligrams) per day, split into several doses, for about two weeks. 

In general, users gradually increase the dose up to 120 micrograms a day and then reduce it over several days until they’re back to the initial dose. They do so for two weeks, take two weeks off, and start again. 

Here’s what a typical Clenbuterol cycle looks like:

Some athletes increase the dosage gradually until the last day of the cycle. Others decrease it toward its end. Another option is to take a small amount daily, such as 40 micrograms, for 16 weeks or more. 

There are no set rules on Clenbuterol dosage. It all comes down to your tolerance. If, say, you feel like your heart is about to jump out of your chest at 80 micrograms a day, consider decreasing the dose or stop taking the drug. 

As the Drug Enforcement Administration notes, Clenbuterol is often abused by athletes, especially women. 

Since it’s a mild androgenic agent, it doesn’t cause fluid retention, body hair growth, deepening of the voice, and other side effects associated with steroids. But this doesn’t mean it’s safe. 

Clenbuterol May Cause Heart Damage 

This popular bodybuilding drug has both immediate and long-term side effects. Over time, it can damage the heart muscle, affect cardiovascular function, or cause cardiac hypertrophy. 

An eight-week study assessed the effects of Clenbuterol on heart size and function in horses. 

Some horses used a treadmill daily, three times per week, and received 2.4 micrograms of Clen per kilogram of body weight twice daily. Others only took the drug, without exercise. Researchers used echocardiography to evaluate their cardiovascular function. 

By the end of the study, all horses treated with Clenbuterol, including those that didn’t exercise, develop major structural changes of the heart. 

At the same time, their VO2 max (maximum rate of oxygen consumption) decreased, meaning that their cardiovascular endurance was much lower. Animals experienced a significant increase in heart size, which raised their risk of aortic rupture and death. 

As the scientists note, previous studies documented the risk of sudden cardiac death in physically active subjects who took Clen. Research conducted on humans confirms that Clen may cause a rapid increase in heart size, as well as liver disorders.

Considering these risks, it’s worth looking for natural alternatives. Sure, there’s nothing wrong about wanting to lose a few pounds, but are you willing to die for it? Probably not. 

From the keto diet to natural fat burners, there are safer ways to get lean and keep the pounds off. A high-protein diet, like the paleo diet, can help you build mass and torch fat. Or you can start tracking your macros and cut calories to get in shape.

Does Clenbuterol Actually Work? 

Current evidence confirms that Clen is an effective fat burner and may improve athletic performance. After all, it is classified as an anabolic agent by the WADA. 

The problem is that most research has been conducted on horses, rats, and other animals, so it’s hard to tell how those findings translate to humans. Since this drug is banned in the U.S., there’s insufficient evidence to support its efficacy. 

According to the Journal of Medical Toxicology, Clenbuterol increases protein synthesis, leading to hypertrophy. At the same time, it promotes fat breakdown through adipocyte β3-adrenoreceptors and causes your body to break down fatty acids. This allows you to build mass while preventing fat accumulation. 

On the negative side, the dosages used for hypertrophy and fat loss are significantly higher than those recommended for the treatment of asthma and other respiratory problems. 

When used in high doses, Clenbuterol can damage your heart and cause serious side effects. Lower doses, on the other hand, are unlikely to produce the desired results. 

Beware that Clen can be extremely addictive. As discussed earlier, a typical Clenbuterol cycle lasts about two weeks, followed by two weeks off. Once you start using the drug, it’s hard to stop. 

Natural thermogenic agents are much safer. Depending on the ingredients used, these supplements can boost your energy and speed up muscle growth in addition to burning fat. 

Take Vintage Burn™, for example. Our formula is produced in FDA-certified facilities, so it’s perfectly legal. It contains no artificial ingredients or GMOs. 

Like Clen, it promotes fat loss, preserves lean mass, and boosts athletic performance — but without any side effects. That’s because it’s made with all-natural ingredients, like green tea extract, caffeine, forskolin, raspberry ketones, and green coffee beans. These compounds are clinically proven to elevate metabolism and facilitate weight loss.

Is Clenbuterol Worth It? 

By now, you should have a better idea of what Clenbuterol does. The risks involved outweigh any potential benefits. Plus, you don’t really know what you’re getting since most pills sold on the black market are counterfeited. 

Clenbuterol does have anabolic and fat-burning effects. But it’s also taken up by other tissues in your body, such as the heart muscle. This can lead to cardiac hypertrophy, cell death, and severe toxicity. 

Beware that Clen will only work if you’re already very lean. If, say, you’re at 12% body fat, the drug may help you get down to 9 or 10%. However, if you’re at 20% body fat, don’t expect significant results. 

Your best bet is to clean up your diet, lift heavy, and add cardio or HIIT to the mix. Consider using a natural fat burner or our Lean Muscle Stack for faster results. 

What’s your take on Clenbuterol? Have you ever tried it? Share your story below to help others make the right choice!