We may write a book about weight loss properties of green tea, bitter orange or cayenne pepper, indicating not only a desired effect on fat burning, but also highlighting the issue of safety of use. However, there are people who don’t look for compromises, for whom only effectiveness matters. An example of a controversial product used both by professional sportsmen and amateurs is a drug – clenbuterol, also called “clen” by some people. This drug, despite the fact that when improperly used may turn out to be very dangerous not only to health but also life, it has one advantage – it burns fat. We don’t speak here about subtle influence on lipolysis and thermogenesis, but about drastic acceleration of metabolism.

What is „clen”?

Clenbuterol is a drug classified to agonists of beta2-edrenergic receptors, used in the treatment of asthma (contrary to what some people claim, it is not a steroid!). In the European countries and the United States, this drug was withdrawn from the pharmaceutical market in 1988 after one of big scandals, but it is still used in veterinary medicine. Clenbuterol widens bronchial tubes, which is especially important to people who use it illegally – it strongly increases thermogenesis, leading to more intensive energy expenditure. Apart from this, the preparation increases blood pressure and has stimulating effect on the central nervous system.

How does „clen” work?

Basically, clenbuterol may be compared to the activity of ephedrine, while it should be highlighted that its effect is much stronger than ephedrine’s. This drug increases the activity of catecholamines (adrenaline, noradrenaline and dopamine), which on the one hand influence the tension of smooth muscles (relax smooth muscles of the respiratory tract and cause tightening of the lumen of blood vessels) and on the other hand they intensify thermogenesis and lipolysis. Catecholamines also have stimulating effect, motivate to act, increase alertness and positively influence muscle tissue oxygenation, thanks to which they increase endurance capacity. Therefore, as can be seen, clenbuterol may be applied not only as a fat burner, but also as a stimulant and endurance booster.

Who can use „clen”?

Clenbuterol is used both by professional sportsmen and by amateurs who deal with physical activity. This drug found application as forbidden doping both by the representatives of bodybuilding and fitness, where it is applied in order to improve the esthetics of the silhouette and get rid of the excess of fat (and it is combined with anabolic-androgen steroids, such as testosterone and its analogues) as well as by sportsmen practicing endurance disciplines (a quite well-known mixture is clenbuterol and erythropoietin used by some competitors during the race).


The dosing of clenbuterol as forbidden support is a strongly individual matter and is dependent on the personal sensitivity to the effect of this preparation. It is practiced very often to start a cycle from the minimal doses (20 – 40 mcg / day) and to gradually increase the dose up to maximally 120 – 160 mcg  / day. In the majority of cases, the dose ranging from 60 to 100 mcg / day turns out to be optimal. The opinions on the duration of the cycle are also divided, some sources say that this product should be taken for 3-4 weeks, but there are some studies suggesting that it can be taken up to 6 or even 8 weeks. There are also some alternative systems, according to which “clen” is used for ca. 2 weeks according to the alternate scheme: 2 days of application /1 day of break and then the product should be exchanged to another preparation such as ephedrine and used for another two weeks.

Combination with other products

Clenbuterol is often combined with anabolic-androgen steroids with low level of aromatization. Remember that in case of using oral products, the risk of liver damage is increased, as “clen” also burdens this organ, about which not everyone knows. Some professionals also practice combining this product with thyroid hormones (T3), which on the one hands leads to drastic acceleration of metabolism, stimulating at the same time fat burning and on the other hand it significantly increases the risk of undesired symptoms and overdosing. Combining clenbuterol with ephedrine and yohimbine may turn out to be exceptionally dangerous.

Undesirable symptoms

The application of clenbuterol as illegal support is certainly related to the risk of some undesirable symptoms. Even small doses of this product may cause tachycardia, muscle shaking, irritation, increase of blood pressure. In higher doses, the effects are intensified and additionally chest pain, nausea, vomit, heartburn, insomnia and many other symptoms may occur. The symptoms of overdosing may be sudden and unpleasant and may lead to the loss of health or even life. There are many cases of severe poisonings with clenbuterol. Absolute contraindications for taking this drug are circulatory diseases (including hypertension) and nervous system diseases. It is worth knowing that studies carried out on animals proved that the application of high doses of clenbuterol cause the occurrence of permanent changes in testicles, liver and muscles.


Clenbuterol definitely turns out to be an incredibly helpful additive during the work on the silhouette’s esthetics directed at reduction of the excess of fatty tissue. The effects resulting from using this product with good diet and proper training may be spectacular. Unfortunately, the application of clenbuterol is related to the high risk of undesirable symptoms, out of which some are only troublesome (shaking muscles and hands), while other may turn out to be simply dangerous. Neither the authors of this article nor the owners and administrators of the portal are the proponents of using forbidden doping preparations.


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