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What is Clenbuterol? (Everything You Need To Know)

Jordan Smith
Published by Jordan Smith | Medical Doctor
Last updated: August 1, 2023
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With almost a decade of being in the fitness industry, I've worked with athletes and bodybuilders who asked about and who actually used clenbuterol to lose excess fat and increase lean muscle mass.

However, because I know that this performance-enhancing drug is a banned substance, I conducted extensive research and gathered as much feedback as I could from people who used it to determine its safety and efficacy, so I can advise my clients accordingly.

After five weeks of research, I’ve compiled my data in this article so both you and my clients can make an informed decision and be aware of all potential risks and benefits.

Let's begin.

Quick Summary

  • Clenbuterol is a medication that can help individuals suffering from bronchial asthma breathe easier by increasing airflow in the lungs, and relaxing muscles.
  • Studies also reveal that Clenbuterol may enhance athletic performance by increasing metabolism, increase muscle mass growth, and improving mental cognition.
  • Some risks linked with Clenbuterol include lowered blood potassium, increased heart rate, anxiety, elevated blood glucose, and low bone mineral density.

What Does Clenbuterol Do?

Spilled white pills top view

Clenbuterol may help people with bronchial asthma breathe easier by relaxing muscles and increasing airflow in the lungs, allowing oxygen to move more freely through the body [1].

Some athletes and bodybuilders have used this drug in an attempt to optimize their breathing, allowing them to have more stamina and get more oxygen into their muscles, allowing them to recover faster after intense training.

However, clenbuterol is not legal in the United States because it has not been approved for human consumption by the Food and Drug Administration (FDA) [2].

Still, many sports enthusiasts continue the use of clenbuterol to help them lose weight and improve their physical performance [3].

How Does It Enhance Athletic Performance?

Clenbuterol may enhance athletic performance by speeding up metabolism, improving mental cognition, and increase muscle mass.

When taken in excess, it has effects as a performance enhancer and a fat-burning aid. It is said to have thermogenic properties, or the ability to raise body temperature, which uses excess energy to produce heat and eventually results in a faster metabolic rate [4].

Having a high metabolism allows excess calories and fats to be burned to provide your mind and body with energy to lift heavier weights, add more repetitions, and train for more extended hours [5].

Furthermore, people taking clenbuterol may experience a sudden increase in blood flow and muscle oxygenation, which can speed up nutrient delivery in their working muscles, healing and repair, and muscle growth [6].

Are There Risks Associated with Taking Clenbuterol?

Man wearing sleeves holding his chest with both hands

There are many health risks associated with taking clenbuterol, which is why it has been prohibited in many countries, including the United States.

Clenbuterol misuse has been shown to have dangerous side effects on health, particularly for new users and those who combine it with anabolic steroids or performance-enhancing drugs [7].

Furthermore, taking this medication above the recommended dosage and duration may result in the following health complications:

Hypokalemia or Lowered Blood Potassium

According to research, acute clenbuterol overdose resulting in low serum potassium concentrations occurs when this substance stimulates the adrenergic nervous system (ANS), allowing extracellular potassium to enter cells [8] [9].

"Having the right amount of potassium is critical for the heart to beat properly. If your potassium levels are too high or too low, the heart is at increased risk of a cardiac arrest."

- John Day, MD, Cardiologist, Intermountain Medical Center Heart Institute

Tachycardia or Increased Heart Rate

Heart rate increased concept

Research suggests that using clenbuterol in high doses may cause prolonged tachycardia or rapid heart rate, atrial fibrillation, and abnormal blood pressure [10].

These cardiovascular side effects can lead to heart enlargement, or cardiac hypertrophy, which raises the risk of a heart attack and stroke [11].

Tremors and Anxiety

One study reveals that consuming higher doses of clenbuterol stimulates the central nervous system (CNS) and causes neurological symptoms such as muscle tremors, anxiety, agitation, and insomnia.

Furthermore, severe drug toxicity can cause seizures and psychosis in some people [12].

Hyperglycemia or Elevated Blood Glucose

Research suggests that using clenbuterol continuously may result in high levels of glucose in the blood [13]. Also, people with high blood sugar may experience symptoms of abnormal sweating and feel warmer than usual [14].

Low Bone Mineral Density (BMD)

Researchers also found that treatment with clenbuterol affects bone metabolism and increases bone resorption, or the destruction of bone tissues, leading to a decrease in bone mineral density and bone loss [15].

Is Clenbuterol Banned In Sports?

Close up image of white circular pills

Clenbuterol is banned in sports at all times, both in and outside of competition, by the World Anti-Doping Agency (WADA) and the International Olympic Committee (IOC) [16].

However, many athletes still use clenbuterol regardless of its many potentially very serious health risks, probably because they believe it helps their bodies burn fat, gain muscle, and perform better.

Nevertheless, clenbuterol is classified by WADA and the IOC as a prohibited drug, and athletes testing positive for this substance may be barred from competing in their sport.


Is Clenbuterol Available for Purchase?

Clenbuterol is only available for purchase in a few countries in Europe and Latin America, where it is legal for the treatment of asthma.

Most countries, including the US, do not yet permit its use as a medicine or sports supplement because it hasn't been proven safe for human use.

How Long Does Clenbuterol Stay in the System?

Clenbuterol can stay in the system for varying lengths of time, depending on the dosage and the user's reaction to the drug.

Additionally, a study on horses discovered that clenbuterol is detectable in the urine for about 14 days and has a half-life of 11.4 hours in the blood [17].

What Is the Safe Dosage of Clenbuterol?

The safe dosage of clenbuterol ranges between 0.02 and 0.04 milligrams per day, which is the recommended dose for treating asthma in several countries where the drug is approved for medical use.

Also, the dosage can differ depending on the drug's use, gender, and tolerance [18].

Is Clenbuterol Effective For Reducing Body Fat?

Clenbuterol taken in higher doses might be effective, but potentially life-threatening dangers associated with this substance abuse vastly outweigh any benefits it might offer in terms of physical performance or reduce body fat.

When my clients want to fast-track their progress, I always recommend natural and legal steroids, which, in conjunction with rigorous diet and exercise, proved to be reliably effective for most of them:

These products are based on only high-quality sources of ingredients, which were scientifically examined for their effects on performance, muscle growth, and fat loss.

Order yours today and see if it’ll make as much of a difference for your fitness journey.


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