Clenbuterol Write Up


SI Founding Member
Dec 16, 2011
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Clenbuterol is an anti asthma medication that belongs to a broad group of drugs known as sympathomimetics. These drugs affect that sympathetic nervous system in a wide number of ways, largely mediated by the distribution of adrenoceptors. There are actually nine different types of these receptors in the body, which are classified as either alpha or beta and further subcategorized by type number of ways, largely mediated by the distribution of adrenoceptors. Clenbuterol has been available as a bronchodilator for decades and is widely used in many parts of the world. Although it has a good safety record and approval in a wide number of other countries, this compound has never been made available for human use in the United States. The fact that there are a number of similar effective asthma medications already approved by the FDA and available may have something to do with this.

In terms of the use of clenbuterol for strength athletes and bodybuilders, its function as a beta-2 agonist can help to increase lypolysis. This is accomplished via an increase in basal metabolic rate, as well as increased heat production in the mitochondria which serves to increase body temperature and therefore increasing thermogenesis. Addtionally, it has been shown that clenbuterol is able to directly stimulate fat cells and accelerate the breakdown of triglycerides, thus forming free fatty acids. All of this is accomplished while clenbuterol has a minimal effect on the user cardiovascularly. This, as stated previously, is due to the drug being a selective beta-2 agonist/antagonist and having a minimal impact on the beta-1 receptors. This should cause less negative side effects, at least cardiovascularly, for the user. A second benefit to the administration of clenbuterol for athletes is an increase in strength as well as a possible increase in muscle size/lean body mass. It has been repeatedly demonstrated in animal studies that clenbuterol contributes to an increase in muscle mass, weight and protein content. The exact mechanism by which this takes place has still not been definitively identified but it can be concluded that it is far different then the response produced by anabolic steroids. Like other beta-2 agonists, clenbuterol has also been shown to increase muscular strength. Again, these results were achieved in animal studies but there is little reason to believe would not be transferable to human users. These gains are made over time and not a result of any type of stimulatory effect of the drug. Again however, the exact mechanism by which these results are achieved with clenbuterol is not known. It is not the same as anabolic steroids but more research needs to be done before a full understanding of this mechanism is known. Clenbuterol does increase muscle protein synthesis so this is likely to contribute but is unlikely to be the only cause. Clenbuterol has an array of potential negative side effects that are indicated in the available research, most of which has been performed using animals. The problem with this is the fact that animals have quite different beta-2 receptor reactions then humans in some cases as well as having a larger quantity of these receptors in the relevant tissues. This obviously could lead to differing reactions in humans then those found in various animals. However due to the lack of research available conducted with human subjects, we are left to decipher the applicability of the animal research that has been conducted. The most commonly reported side effects associated with clenbuterol are tremors, increased heart rate, increased sweating, restlessness, headaches, and loss of appetite. The only way to prevent or reduce such symptoms from occurring is to either reduce the dosing being administered or ceasing to use the drug completely.

Athletes and bodybuilders taking clenbuterol to lose body fat usually take 1-3 40mcg pills per day with the dosage usually being split up. The receptors will eventually get used to the drug and some time should be taken off to allow them to down regulate. Because of this many choose to run a 2 week on and 2 week off schedule.


SI Founding Member
Dec 16, 2011
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What is Clenbuterol?

Clenbuterol is a beta-2 agonist and is used in many countries as a broncodilator
for the treatment of asthma. Because of it's long half life, clenbuterol is not
FDA approved for medical use. It is a central nervous system stimulant and acts
like adrenaline. It shares many of the same side effects as other CNS stimulants
like ephedrine. Contrary to popular belief, Clenbuterol has a half life of 35
hours and not 48 hours.

Dosing and Cycling

Clenbuterol comes in 20mcg tablets, although it is also available in syrup, pump
and injectable form. It's also available as a powder in some areas. Doses are
very dependent on how well the user responds to the side effects, but somewhere
in the range of 4-8 tablets per day for men and 2-4 tablets a day for women is
most common. Clenbuterol loses its thermogenic effects after around 8 weeks when
body temperature drops back to normal. Its anabolic/anti-catabolic properties
fade away at around the 18 day mark. Taking the long half life into
consideration, the most effective way of cycling Clen is 2 weeks on/ 2 weeks off
for no more than 12 weeks. Ephedrine or Yohimbine can be used in the off weeks.

Clenbuterol vs Ephedrine vs DNP

Ephedrine will raise metabolic levels by about 2-3 percent and 200mg of DNP
raises metabolic levels by about 30 percent. Clenbuterol raises metabolic levels
about 10 percent and it can raise body temperature several degrees.

DNP is by far the most effective fat burner but many people will never use it
because of the risks associated with it. It also offers no anti-catabolic
benefit. Although it does have anti-catabolic effect, ephedrine's short
half-life prevents it from being all that effective.

As far as side effects, Clenbuterol's are certainly milder than DNP's, and some
would even say milder than an ECA stack. There is no ECA-style crash on
Clenbuterol and many users find it easier on the prostate and sex drive. This
may in part be due to the fact that Clen is generally used for only 2 weeks at a

Side effects


The most significant side effects are muscle cramps, nervousness, headaches, and
increased blood pressure.

Muscle cramps can be avoided by drinking 1.5-2 gallons of water and consuming
bananas and oranges or supplementing with potassium tablets at 200-400mg a
day taken before bed on an empty stomach. Taurine at 3-5grams is a necessity in
minimizing cramps.

Headaches can easily be avoided with Tylenol Extra Strength taking at the first
signs of a headache.

Common Uses

post-cycle Therapy: Clen is used post cycle to aid in recovery. It allows the
user to continue eating large amounts of food, without worrying about adding
body fat. It also helps the user maintain more of his strength as well as his
intensity in the gym. Diet: Roughly the same as on cycle.

Fat loss: The most popular use for Clen, it also increases muscle hardness,
vascularity, strength and size on a caloric deficit. For the most significant
fat loss, Clen can be stacked with T3. Diet: A high protein(1.5g per lb of
bodyweight), moderate carb(0.5g to 1g per lb of bodyweight), low fat diet(0.25g
per lb of bodyweight) seems to work best with Clen.

Alternative to Steroids: Clenbuterol has mild steroid-like properties and can be
used by non-AS using bodybuilder to increase LBM as well as strength and muscle
hardness. Diet: A moderate carb, high protein, moderate fat diet work well.

Stimulant/Performance Enhancement: It can be used as a stimulant, but an ECA
stack may be a better choice because of it's much shorter half-life. Diet: To
take full advantage of the stimulatory effects of Clen, carbohydrates must be
included in the diet. Ketogenic diets do not work well in this case.

Precautions: Is Clen for you?

The same precautions that apply to Ephedrine must be applied to Clen, although
some people find ECA stacks are harsher than Clen. It should not be stacked
with other CNS stimulants such as Ephedrine and Yohimbine. These combinations
are unnecessary and potentially dangerous. Caffeine can be used in moderation
before a workout for an extra quick. burst of energy.

A word on Ketotifen

Ketotifen is safe antihistamine used extensively some European countries to
treat asthma and allergies. It can up regulate beta-2-receptors that Clen down
regulates. Basically, it allows users to extend their use of Clen for 6-8 weeks
at a time. 2-3mg a day is ideal, 10mg as found in "superclen" can make users
extremely drowsy. It also increases the effectiveness of Clen so doses must be
adjusted accordingly. The downfall of this drug is its ability to induce
extreme hunger is some people, which is not a desirable state to be in when

Cycling Clenbuterol

Most users that report bad side effects and discontinue use are those who use
high doses right at the start of the cycle. The worst side effects occur within
the first 3-4 days of use.

A first time user should not exceed 40mcg the first day. Increase by one tab
until the side effects are not tolerable

Example of a first cycle:

Day1: 20mcg
Day2: 40mcg
Day3: 60mcg
Day4: 80mcg
Day5: 80mcg(Note: Increase the dose only when the side effects are tolerable)
Day6-Day12: 100mcg
Day13: 80 mcg (Tapering is not necessary, but it helps some users get back to
normal gradually)
Day14: 60 mcgs
Day15: off
Day16: off
Day 17: ECA/ NYC stack

Example of a second cycle:

Day1: 60mcg
Day2: 80mcg
Day3: 80mcg
Day4: 100mcg
Day5: 100mcg
Day6-Day12: 120mcg
Day13: 100 mcg
Day14: 80 mcgs
Day15: off
Day16: off
Day 17: ECA/ NYC stack

What else do I need to know?

Taurine MUST be used with Clen at 3-5g daily. Clenbuterol depletes taurine
levels in the Liver which stops the conversion of T4 to T3 in the Liver.
Taurine allows the user to avoid the dreaded rebound effect and painful muscle
cramps. It's a must with Clen.

Clenbuterol should not be taken too close to a workout. It can interfere with
your breathing and complete ruin your workout. When doing cardio, it's
advisable to stay at a consistent pace and avoid HIIT style routines.

Do not take Clen Past 4pm and drink plenty of water; 1.5-2 gallons a day.