Clenbuterol Side Effects


Clenbuterol side effects share the exact same attributes with that of any other stimulant compound. Any compounds belonging to the stimulant family (such as Caffeine, Albuterol, Ephedrine, Epinephrine, Norepinephrine, and so on and so forth) share the exact same side effects to varying degrees. The differences between these individual compounds in this family of sympathomimetics tends to be the level of intensity (or severity) of the different side effects associated with stimulants. Different stimulant-like side effects can possibly be less prominent with one compound in comparison to another (for example, Ephedrine versus Caffeine). Even though one side effect may be less pronounced in a particular compound, a different associated stimulant-like side effect may be much stronger. A perfect example would be that of Ephedrine versus Clenbuterol. Many experienced individuals who have used both compounds (separately instead of stacked together) have reported that an experience with one of these compounds has exhibited more of a particular side effect than the use of the other compound. At the end of the day, however, the general side effects attributed to sympathomimetic stimulants remain the same across the board. This having been said, Clenbuterol side effects accompany the exact same side effects as those of other CNS stimulants. These common shared side effects include: tremors (shaky hands), insomnia, sweating, headaches, heightened blood pressure, and nausea. Stimulants like Clen also possess the potential for some side effects that are not commonly listed. These psychological side effects can include: anxiety, heightened euphoric sensation (improved mood), and depression (resulting from a possible ‘stimulant crash’ following cessation of use). The less common and rarer side effects associated with stimulants (predominantly associated with overdoses) include: tachycardia (rapid heart rate), irregular heart rate, rapid breathing, severe nausea, vomiting, and diarrhea. It is important to note for those unaware of the distinguished difference between Clen and anabolic steroids – Clenbuterol is not an anabolic steroid and thus there are no side effects associated with anabolic steroids where Clenbuterol is concerned (i.e. no virilization effects, androgenic effects, or Estrogenic effects). One Clenbuterol side effect that is unique in particular to Clenbuterol (and its close sister compound Albuterol) is: muscle cramps, which will be further discussed shortly.


Common Side Effects Associated With Clenbuterol

It has been previously touched upon that Clenbuterol side effects share the most common side effects associated with the whole stimulant family of drugs: tremors (shaky hands), insomnia, sweating, headaches, heightened blood pressure, and nausea. Individuals using Clenbuterol are most likely to experience these side effects, as they are side effects that are fairly common and most users will more than likely experience them. When the topics of side effects are discussed, it must be understood that various users may be sensitive (or even hypersensitive) or certain side effects while others may not be. Therefore, the total responsibility falls upon the individual themselves as to whether or not to act accordingly depending on their response level and type to certain side effects. This also includes various unforeseen side effects such as allergic reactions (rashes, hives), which are generally very rare with Clen but there do exist users that succumb to allergic reactions. In any case, the majority of the common stimulant side effects shared among the whole stimulant family generally subside with use, as the body becomes accustomed to the effects of the drug.



Tremors: This is perhaps the most common Clenbuterol side effect touted across the world by users. Tremors resulting from Clenbuterol use tend to be far more pronounced with Clenbuterol than with other stimulant drugs. Other stimulants such as Caffeine or Ephedrine do in fact exhibit this same side effect, but it is far less pronounced. There is unfortunately no ‘cure’ for this Clenbuterol side effect, but the tremors tend to frequently subside with regular use as the body becomes slowly accustomed to dosing protocol. Hence, this is one of the important reasons for a slow ramp-up in dosing when beginning Clenbuterol use. The majority of users tend to report diminished intensity of tremors during the later weeks of Clenbuterol use due to the body acclimatizing to the stimulant.

Insomnia: A frequently reported Clenbuterol side effect, however, insomnia is a common side effect associated with any stimulant. The primary issue with insomnia where Clenbuterol is concerned is with its extremely long half-life of 37 hours. It is because of this that many users have suffered insomnia as a side effect. There are many users who have also reported the ability to be able to sleep normally as well, indicating that the insomnia side effect may only affect users sensitive to this side effect. Those who do experience it have also reported the incidence of insomnia becoming less and less as time on the drug passes, once again due to the body becoming accustomed to the stimulant effects.

Sweating: Clenbuterol is a Beta-2 agonist, and triggers lipolysis (fat breakdown) through this pathway. The result is more adipose tissue (fat tissue) being utilized as a fuel source. What results from this is an increase in heat as a result of more fats being metabolized and utilized as energy. The resulting thermogenic (heat generating) effect comes in the form of an increase in body temperature. The end result of this increased body temperature is of course increase perspiration (sweating). The elevation in temperature should normally be no higher than approximately 0.5 – 1 degree, and sometimes slightly higher than that. This increase in body temperature is rarely ever uncomfortable, but can often result in increased perspiration (especially in a hotter ambient environment).

Increased blood pressure and headaches: Elevated blood pressure and headaches are commonly associated with one another in a cause and effect relationship. Rising blood pressure (as a result of vasoconstriction in most areas of the body) usually leads to an increase in the incidence and severity of headaches. Blood pressure elevations tend to decrease with continued use as the body becomes accustomed to the stimulant, but often times this will not be the case and every user must be aware of this. Therefore, all individuals using Clenbuterol should monitor blood pressure frequently throughout Clenbuterol use and to ensure that levels do not rise to higher dangerous levels. Dangerously high levels of blood pressure have commonly been touted as ‘the silent killer’ due to the fact that rarely will individuals with dangerously high blood pressure ever ‘feel’ anything wrong with them. It is a highly recommended decision to abstain from Clenbuterol use if an individual knowingly possesses a history of blood pressure issues and hypertension. In such a situation, the individual were to use Clenbuterol, these conditions can and will worsen. Some factors that can be monitored and controlled to deal with elevated blood pressure are control of sodium intake and any possible consumption of other CNS stimulants (such as Caffeine, Ephedrine, etc.) while using Clenbuterol, especially the stronger prescription stimulants such as Adderall (Amphetamines) and anything similar.

Nausea: This side effect is generally associated with anything administered orally, and includes food. Any substance ingested and passed through the digestive system always has potential to cause nausea in individuals, especially those sensitive to this particular side effect. Stimulants themselves can actually further potentiate this side effect, where individuals who possess a hypersensitivity to stimulants can experience nausea from the stimulant side effects themselves rather than the issue of stomach sensitivity.

Muscle cramps: This is one particular side effect that is unique to Clenbuterol side effects. Many users report muscle cramps during use of Beta-2 agonists such as Clenbuterol or Albuterol. Studies have demonstrated that the use of Clenbuterol depletes levels of the amino acid Taurine both in muscle tissue as well as serum blood plasma[1][2]. Taurine, Magnesium, Potassium, and Sodium all play important key roles in the regulatory functioning of the bioelectrical nerve impulses and nerve signals that control the contraction and relaxation of all types of muscle tissue. The depletion of Taurine in this particular case can lead to a disruption in this function, and what results are involuntary and often painful muscle cramps. The solution to solving the uncomfortable cramping is that of Taurine supplementation daily during the use of Clenbuterol at a dose of approximately 2.5 – 5 grams daily and is also dependent on each individual and how they respond in particular to this side effect.

General Effects and Risks Of Clenbuterol Use

It has been mentioned already that Clenbuterol studies have been conducted on both humans as well as animals, however, animal studies on Clenbuterol are far more frequent and abundant. Therefore, the majority of information we have access to in terms of Clenbuterol are that of clinical studies performed on animals. What must be remembered with any drug or compound is the general rule that the effects and side effects are primary dose and duration dependent, and what is equally as determining is the individual’s genetic response and unique factors that pertain to that individual.

The few studies that have been performed on humans in regards to anabolism of muscle tissue has demonstrated some favorable results, although there is far more evidence of Clenbuterol demonstrating anabolism in animals. One particular study on healthy test subjects involved the administration of Clenbuterol at high doses, and resulted in the promotion of cardiac recovery while it also lead to a significant increase in lean mass[1]. This study involved the test subjects administered Clenbuterol orally over a period of 46 weeks, and were slowly given Clenbuterol in steadily increasing doses of 20mcg per week until a peak daily dose administration of 720mcg per day (hence the emphasis that the test subjects were administered Clenbuterol at “high doses”[2]. It should be noted, however, that these test subjects had their Clenbuterol dosages slowly titrated upwards, and that the final optimal dose would be considered far too much for an individual using it for fat loss, and that the more common peak doses for fat loss (approximately 120mcg/day) would likely elicit a less significant impact on muscle anabolism than a 720mcg per day dose, as administered in the study.

What may not be fully known by the average user is that the studies conducted on animals as well as humans have in fact demonstrated the negative effects that Clenbuterol may exhibit on cardiac tissue. A common question asked by individuals who use or are seeking to use Clenbuterol is that of what possible effect are there on the heart and related tissues and organs? The important distinction to note and remember here is the context and environment of the study in which Clenbuterol was administered to the test subjects. There have been numerous studies demonstrating Clenbuterol’s effect of cardiac tissue cell death in rats, but the context must be understood where the amounts of Clenbuterol administered to rats would come to the equivalent of massive overdoses for a human. One particular study had observed two male bodybuilders (ages 18 and 22 years) that were admitted to the Emergency Room suffering from palpitations, nausea, vomiting, chest pain, diaphoresis and tachycardia shortly after ingesting Clenbuterol. It was found that myocardial ischemia was the result of Clenbuterol use from these two bodybuilders[3]. Mycardial ischemia is a condition in which there is a local insufficiency of blood supply to the heart, which is a result of arterial vasoconstriction (caused by Clenbuterol).  What exactly were the circumstances surrounding these two bodybuilders were remains unknown (whether or not they had knowingly or unknowingly overdosed, or perhaps reacted badly due to an unforeseen individual response).

Another study on rats was conducted where rats were administered 1 microgram per kg to 5 micrograms per kg every day. The rats in the control group saw no necrotic damage in cardiac tissues, however, discernible myocyte necrosis was found in both heart muscle as well as the soleus muscle after Clenbuterol administration in the group of rats that were administered Clenbuterol[4]. Any person with a sharp mind would notice that in this study, 5mg/kg is an absolutely astronomically massive dose of Clenbuterol when one would realize that Clenbuterol is typically used in the mcg (microgram) range as opposed to the mg (milligram) range. As an example, a 5mg/kg daily dose for a 90.7kg (200lb) adult would be the equivalent of 450mg daily. The equivalent of 450mg of Clenbuterol measured in mcg would be 450,000mcg daily. When the peak recommended dose for fat loss of 120-160mcg daily is kept in mind, one can see where the flaw lies in these studies. However, this is not an advisement for individuals to discredit the results of these studies. One must also always remember the results of these studies.

Along with the studies already shown, heart damage as a result of Clenbuterol use does tend to be a regular occurrence and trend in animal studies which happen to vary the dosing schemes and administration amounts. The majority of this revolves around such things as cardiac hypertrophy, enlargement of ventricles, and cardiac necrosis[5]. With all of this data kept in mind, it is highly advisable that any individual considering Clenbuterol use should have various medical tests conducted to confirm or disqualify the existence of any underlying medical or congenital diseases/conditions (especially where cardiac tissue is concerned) that could be worsened by Clenbuterol use.


Clenbuterol References:

[1] Clenbuterol increases lean muscle mass but not endurance in patients with chronic heart failure. Kamalakkannan G, Petrilli CM, George I, LaManca J, McLaughlin BT, Shane E, Mancini DM, Maybaum S. J Heart Lung Transplant. 2008 Apr;27(4):457-61. doi: 10.1016/j.healun.2008.01.013.

[2] Effect of clenbuterol on cardiac and skeletal muscle function during left ventricular assist device support. George I, Xydas S, Mancini DM, Lamanca J, DiTullio M, Marboe CC, Shane E, Schulman AR, Colley PM, Petrilli CM, Naka Y, Oz MC, Maybaum S. J Heart Lung Transplant. 2006 Sep;25(9):1084-90.

[3] Myocardial Ischemia Associated with Clenbuterol Abuse: Report of Two Cases. J Emerg Med. 2012 May 24. Huckins DS, Lemons MF. Department of Emergency Medicine, Newton-Wellesley Hospital, Newton, Massachusetts.

[4] Myotoxic effects of clenbuterol in the rat heart and soleus muscle. Journal of Applied Physiology, 22 February 2002. Jatin G. Burniston, Yeelan Ng, William A. Clark, John Colyer, Lip-Bun Tan, and David F. Goldspink


[5] Chronic clenbuterol administration negatively alters cardiac function. Sleeper MM, Kearns CF, McKeever KH. Med Sci Sports Exerc. 2002 Apr;34(4):643-50.