Muscle Sport Magazine

CLENBUTEROL (Clenbuterol Hydrochloride)

By Leigh Penman

In the last few years Clenbuterol has replaced Ephedrine as the drug of choice when it comes to fat loss and contest preparation in general. Clenbuterol is used throughout the world as a bronchodialator and, when used this way, it is highly effective with a low level of user complaints. In terms of fat loss, ‘Clen’ (as it is frequently called) is what is known as a
Repartitioning agent – meaning that it will increase your ratio of Fat Free Mass to Fat Mass.

Clenbuterol belongs to a class of drugs known as sympathomimetics. These drugs affect the sympathetic nervous system in numerous ways. It is specifically a selective beta-2 sympathomimetic, stimulating the beta-2 receptors, which creates a thermogenic effect, directly stimulating fat cells and accelerating the breakdown of triglycerides to form free fatty acids. Animal studies have also shown it to be quite anti-catabolic and/or anabolic which obviously leads to its attractiveness amongst bodybuilders – particularly during the pre-contest phase. However, it has to be said that these studies have been restricted to animals and there is little real evidence of Clenbuterol having muscle building/sparing properties in humans. This does little to tarnish its reputation as a great adjunct anabolic – used both off-season and pre-contest.


Another attractive quality of this drug is its extremely long half-life in the body – which gives it an active life of approximately 34-36 hours. This makes it easy to maintain steady blood levels with a single or twice daily dosing schedule. Interestingly enough, Clenbuterol has never been approved for use in the USA (perhaps the drug companies would not find it profitable enough). This does little to affect its availability on the black market however, with many foreign preparations being readily available.


Clenbuterol is generally a drug where you have to gradually assess your own individual tolerance level. Basically, it is advisable to start with 20mcgs upon rising. If the side effects (possible anxiety, shaking and sweating) are not too pronounced, then the same dose can be repeated later in the day. Men generally end up in the range of 2-8 tablets a day. Women usually find 2-4 to be very effective.
As previously suggested, Clenbuterol does have a fair amount of side effects – most of which will be familiar to anyone who has used CNS stimulants. Along with a slight increase in body temperature (due to the thermogenic effect) users may experience shaky hands, insomnia, sweating, increased blood pressure and nausea. These side effects usually become less noticeable once the user becomes accustomed to the drug. They are also dose dependant – which is why it is always advised to begin on a low dose in order to gauge your tolerance level.


One of the main drawbacks with this drug is that after a couple of weeks it seems to stop working for most people. This is due to the fact that it can cause a down regulation of the beta-receptors in the pulmonary, cardiac and Central Nervous System. One way to sense this down regulation is when you no longer feel an elevation in body temperature following administration. This suggests that the substance is no longer exhibiting a thermogenic effect. At this point increasing the dosage would not be very effective and a break of at least two weeks should be taken before it is used again. This accounts for the popular two weeks on/two weeks off method of administration. There is however much controversy in this area. Some say it can promote fat loss for approximately 4-6 weeks, though any strength gains can usually only be felt for 3-4 weeks (probably due more to the stimulant properties rather than any real anabolic effect).

The use of anti-histamines such as Benadryl or Ketotifen every 3rd or 4th week may help prevent this tolerance to some extent – although they should be taken at bedtime since they will cause drowsiness.

It has also been found that Clenbuterol depletes the body of the amino acid Taurine, so you may want to supplement with this during a cycle of Clen.


However you decide to incorporate this substance into your program, you must always start low and never go above 8 tablets a day (with a complete maximum being 200mcgs). Monitor your blood pressure and keep it at (or below) 140/90. If it goes above that, or if side effects become intolerable use your common sense and decrease the dose.


Many competitive athletes find that the fat burning effects of Clenbuterol can be enhanced by combining it with thyroid hormones (particularly Cytomel). The thermogenic effect in this instance can be very powerful. When combined these cutting agents can even counter the fat storing effects of strong aromatizing androgens. A Clenbuterol/thyroid mix is also common when using growth hormone, as it seems to increase the thermogenic and anabolic effect significantly.

Leigh Penman, in addition to be a staff writer at MuscleSport Mag, has been writing for bodybuilding magazines, websites and nutritional supplement companies since 1985. Whilst residing in the UK, she earned the reputation of being one of the top female writers in bodybuilding-related media. Her credits included being a contributing editor on all the magazines in production as well as filling the shoes of Ladies Editor and Showbiz Editor on two publications (the later being on Arnold’s sanctioned magazine, ‘Bodypower’). During this time she also competed successfully on four occasions (placing in the top four in all contests).

Relocating to New York in the late 1990s she focused her writing attention to crystal healing techniques and metaphysics – however, she still maintained a five day workout schedule during this time and gained her personal training certificate.

Having also studied pharmacology in relation to sports performance, her writing began taking her in that direction until the present day which sees her embarking on a return to the magazine world, as well as extending her web-related work in the bodybuilding and fitness field.

Leigh has been working out for close to thirty years so she is clearly a writer who ‘walks her talk.’
She can be contacted personally at or you can also check her out at New York’s favorite metaphysical store


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