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 U.S. in the past, clenbuterol has been used in animal rearing as well as by vets. In 1991, the U.S. 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.
Why is clenbuterol used?
Clenbuterol’s initial use was as an asthma drug. However, bodybuilders, performance athletes, and those wanting to lose weight are now using the drug.
Clenbuterol can be used as a weight-loss aid because it can increase a person’s metabolism. As well as reducing body fat and weight, it also allows the user to retain both muscle mass and body strength at the same time.
Clenbuterol became known as a celebrity diet secret because of its apparent use by celebrities and famous athletes.
One study reviewing data from two regional poison centers in the U.S. found that in 11 of the 13 reported casesTrusted Source of people taking clenbuterol, it had been used for weight loss reasons or as part of a bodybuilding regime.
The World Anti-Doping Agency have banned the use of clenbuterol at all times, both in and outside of competition.
Athletes and bodybuilders taking clenbuterol will often work on a program cycle that includes on and off periods.
Such a program could mean 2 days taking clenbuterol and 2 days without taking any, or perhaps a week taking the drug followed by a week of none.
Dosage can vary, depending on factors that include gender and tolerance, and it can be taken orally or injected.
Both methods have risks. Injections can cause scarring or air bubbles to form in the blood, while tablets can affect the liver.
When used in Europe and Latin America to open up the airways in cases of asthma, the recommended dose is 0.02–0.04 milligrams (mg) per day.
Risks and 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:
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 high in protein, moderate in carbohydrates, and low in fat.