Clenbuterol is a steroid-like chemical that was initially developed to treat asthma in horses, working by relaxing the airways in the animals’ lungs.

The drug is both a decongestant and a bronchodilator. A decongestant thins the blood to reduce blood pressure while a bronchodilator widens the vessels that carry oxygen, so the volume of oxygen in the blood increases.

In some European and Latin American countries, clenbuterol is approved as an asthma drug for humans too. But, in the United States, it is a banned substance for this purpose.

In the US in the past, clenbuterol has been used in animal rearing as well as in vets. In 1991, the US Food Safety and Inspection Service found it had been fed to livestock, so the animals gained more muscle and less fat. But, again, in many countries, clenbuterol is illegal for animal use.

The drug is now controversial because of its use in bodybuilding and  weight-loss  programs.

In this article, we take a look at how clenbuterol works, when it is used, and what the risks are for people who take it.

clenbuterol side effects

The reason clenbuterol is banned in so many countries and has become so controversial is that many side effects are associated with it.

Many of the side effects are the same as those associated with amphetamines, including:

anxiety
shaking headaches
abnormal
sweating
raised body temperature
Clenbuterol can also have negative effectsTrusted Source on the heart, such as heart palpitations, atrial fibrillation or an irregular and often fast heartbeat, and problems with blood pressure.

Increased heart rate and dilation caused by the drug can lead to what is known as cardiac hypertrophy. This condition is when the heart grows to an abnormal size, which in turn can lead to a heart attack and eventually death.

Also, clenbuterol contains dopamine, which is commonly known as the reward hormone. Dopamine is closely associated with addiction. As such, clenbuterol can be highly addictive.

In many countries, clenbuterol is banned from being used in animals that will be consumed by humans.

In 1994, 140 people in Spain were hospitalized after eating meat tainted by clenbuterol. Similarly, in 2006, 336 people in China were poisoned after eating pork that contained it.

Clenbuterol can reduce the amount of potassium naturally occurring in the body. Consequently, those taking it as a drug will often also eat an increased amount of bananas to replace the potassium.

Athletes will often accompany the taking of clenbuterol alongside a diet that is hig h in protein, moderate in carbohydrates, and low in fat.