Clenbuterol: Benefits, Risks, Side Effects & Safer Alternatives

Clenbuterol word cloud with related terms.

What is Clenbuterol?

Clenbuterol, also referred to as “Clen”, is a beta-2 adrenergic agonist that in low doses dilates the bronchial passages in the lungs. For this reason, it appears under the trade name Dilaterol, among other names.

The drug has medical uses in the treatment of asthma and chronic obstructive pulmonary disease (COPD), but the FDA does not approve Clenbuterol for treatment of humans in the US. However, it is approved to improve respiratory function in horses.

At higher doses, the adrenergic effects of Clenbuterol boost metabolism and lead to the development of lean muscle mass. Livestock sometime receive Clenbuterol as a way of increasing lean meat content.

Bodybuilders and athletes sometimes take high doses of Clen to burn fat and build muscle mass, which has led the World Anti-Doping Agency to classify the drug as a banned anabolic performance-enhancing drug. The use of Clenbuterol for livestock has even led some athletes to avoid meat products that may unintentionally expose them to Clenbuterol.


As an adrenergic receptor agonist, it can increase one’s metabolic rate, potentially decreasing fat, inducing weight loss, and promoting the development of lean muscle. Other adrenergic receptor agonists have similar effects.

While Clenbuterol is an effective bronchodilator, there are other medications for this purpose that are legal to prescribe in the US. There is evidence in rat studies to suggest that Clenbuterol has anabolic effects that are distinct from the effects of other adrenergic receptor agonists.

Due to its ability to accelerate fat oxidation, clenbuterol is primarily used by bodybuilders as a cutting supplement for losing weight prior to a competition. It is also frequently stacked with a steroid, especially when seeking to preserve muscle mass.

Side Effects

Particularly at high doses, Clenbuterol has side effects similar to the effects of adrenaline, such as:

  • Accelerated heart rate.
  • Heart palpitations
  • Chest pain
  • Anxiety
  • Tremors
  • Fatigue
  • Risk for dependency
  • Potential risk of myocardial infarction or heart attack in cases of overdose

There is some evidence that Clenbuterol is toxic to the heart, and there is at least one case of rhabdomyolysis (muscle degeneration) linked to Clenbuterol abuse. The severity of these side effects, coupled with a limited amount of data, makes human use of Clenbuterol in any context a risky practice.

Clenbuterol, classified as a beta-2 agonist, should not be used in conjunction with other beta agonists. Due to the limited use of Clenbuterol in humans, there is very little information available about Clenbuterol’s adverse reactions with other drugs.

Taking Clenbuterol together with other medications that affect the heart could lead to additional, and potentially fatal side effects.

Clenbuterol Alternatives

Clenbuterol is a popular stimulant among bodybuilders due to its effects on weight loss and muscle growth. But there are risks and side effects associated with clenbuterol use, which I why I recommend in the strongest terms the use of safer, all-natural alternatives.

There are a few really good legal alternatives available that provide many of the same effects as Clen, but without having any of the negative side effects. These supplements are not only safe but also effective and reasonably priced.

I’ve tested a number of clen-like supplements over the years, many of which were absolute crap, but three that I can whole-heartedly recommend are:

These supplements are ideal alternatives for anyone who wants to quickly get ripped, burn fat, or push their workout performance through the ceiling. These products also come with little-to-no side-effects or risks to your health, which is why they’ve become as popular as they have.


The only approved use of Clenbuterol is for lean muscle development and the treatment of respiratory disorders in horses and cattle. Its effects on humans are less well-documented, and the precise strength of its anabolic activity, if any, in humans is not known.

In light of the uncertainty surrounding the benefits of Clenbuterol and the severity of the potential side effects, it is difficult to view Clen as being a better option when there are safer non-medical performance-enhancing alternatives available.

For more information about natural supplements that mimic the effects of steroids, be sure to see our list of the Top 5 Best Legal Steroids.

Anabolic Research display of product bottles.

The claims in this article are for informational purposes only and are not meant to be a substitute for medical advice. Consult your physician for information about treatment for asthma, treatment for COPD, and athletic performance.

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