Clenbuterol: Uses, side effects, and risks Health ConditionsHealth ConditionsAlzheimer's & DementiaAnxietyArthritisAsthma & AllergiesBreast CancerCancerCardiovascular HealthCOVID-19Dermatology & SkincareDiabetesEnvironment & SustainabilityExercise & FitnessEye HealthHeadache & MigraineHealth EquityHIV & AIDSHuman BiologyInflammatory Bowel DiseaseLeukemiaLGBTQIA+Men's HealthMental HealthMultiple Sclerosis (MS)NutritionParkinson's DiseasePsoriasisSexual HealthWomen's HealthDiscoverNewsLatest NewsOriginal SeriesMedical MythsHonest NutritionThrough My EyesNew Normal HealthPodcastsHow to understand chronic painWhat is behind vaccine hesitancy?The amazing story of hepatitis C, from discovery to cureNew directions in dementia researchCan psychedelics rewire a depressed, anxious brain?Why climate change matters for human healthToolsGeneral HealthDrugs A-ZHealth HubsHealth ToolsBMI Calculators and ChartsBlood Pressure Chart: Ranges and GuideBreast Cancer: Self-Examination GuideSleep CalculatorHealth ProductsAffordable Therapy OptionsBlood Pressure MonitorsDiabetic SuppliesFitness TrackersHome GymsGreen Cleaning ProductsHow to Shop for CBDQuizzesRA Myths vs FactsType 2 Diabetes: Managing Blood SugarAnkylosing Spondylitis Pain: Fact or FictionConnectAbout Medical News TodayWho We AreOur Editorial ProcessContent IntegrityConscious LanguageNewslettersSign UpFollow UsMedical News TodayHealth ConditionsDiscoverToolsConnectSubscribe What is clenbuterol Medically reviewed by Alan Carter, Pharm.D. — By Tom Seymour — Updated on August 11, 2022Clenbuterol is a chemical called a beta-2-adrenergic agonist. It has approval in the United States for use in horses with breathing difficulty. It works by relaxing the airways in the animals’ lungs. Clenbuterol is both a decongestant and a bronchodilator. A decongestant works by narrowing and constricting blood vessels to reduce congestion. Conversely, a bronchodilator helps relax the muscles around the airway, which in turn opens it up. In some European and Latin American countries, clenbuterol has approval for human use as an asthma drug. However, in the U.S, it is banned to use it for this purpose. The drug is also controversial because of its use in bodybuilding and weight-loss programs. In this article, we take a look at how clenbuterol works, its uses, and what the risks are for people who take it. What does clenbuterol do Share on PinterestShikhar Bhattarai/StocksyAs a beta-2-adrenergic agonist, clenbuterol stimulates the heart and central nervous system, so it has the opposite effect as a beta-blocker. It has a similar stimulating effect on the body as epinephrine and amphetamines. This stimulation leads to various effects, such as:rapid fat burningexcitabilitynervousnessincreased energygreater determination Why do people use clenbuterol Clenbuterol’s initial use was as an asthma drug. However, bodybuilders, performance athletes, and those wanting to lose weight are now using it. People can use clenbuterol 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 reviewed data from two regional poison centers in the U.S. It found that in 11 of the 13 reported cases of those taking clenbuterol, people had used it for weight loss reasons or as part of a bodybuilding program. The World Anti-Doping Agency has banned the use of clenbuterol at all times, both in and outside of competition. Clenbuterol dosage Athletes and bodybuilders taking clenbuterol will often work on a program cycle that includes on and off periods. The dosage can vary depending on factors that include gender and tolerance. People can take it orally or via injection, but both methods carry risks. Injections can cause scarring or air bubbles to form in the blood, while oral tablets can affect the liver. When people use it in Europe and Latin America to open the airways in those with asthma, the recommended dose is 0.02 to 0.04 milligrams daily. Clenbuterol risks and side effects Clenbuterol is banned in many countries and has become so controversial because it has links to many side effects. Many of these side effects are the same as those relating to amphetamines, including:anxietyshakingheadachesatypical sweatingraised body temperature Clenbuterol can also negatively affect the heart, causing some symptoms such as heart palpitations, atrial fibrillation, which is an irregular and often fast heartbeat, and problems with blood pressure. Increased heart rate and dilation from using the drug can lead to cardiac hypertrophy. This condition is when the heart grows to an atypical size, which in turn can lead to a heart attack and eventually death. Many countries have banned clenbuterol from being used in animals that humans will consume. In 1994, 140 people in Spain required hospitalization after eating meat containing clenbuterol. Similarly, in 2006, 336 people in China were poisoned after eating pork that contained it. Clenbuterol can reduce the amount of naturally occurring potassium in the body. Consequently, those taking it as a drug will often also eat extra portions of bananas to replace the substance. Athletes will often combine taking clenbuterol alongside a diet high in protein, moderate in carbohydrates, and low in fat. Current clenbuterol research There has been an increase in clenbuterol use as a drug for bodybuilding and weight-loss purposes, with people obtaining it via the internet. However, due to the hidden dangers of the drug, there can be serious risks for those who take it regularly. The Department of Emergency Medicine in Newton, MA, reported two cases of people requiring medical attention and treatment because of clenbuterol use. The men were bodybuilders aged 18–22 years who had heart palpitations, nausea, vomiting, and chest pain shortly after taking clenbuterol. The Peking Union Medical College in Beijing, China, found that low doses of clenbuterol had minimal effects when the researchers tested them on rabbits. However, medial doses significantly affected the animals’ heart rates, and higher doses even led to death. Outlook Clenbuterol’s effects on the heart and muscles depend on how high a dose someone has been taking and for how long. The risks increase with the dose and duration. Those taking high doses can quickly experience long-term side effects, such as a decrease in the heart’s size, weight, strength, and activity. Clenbuterol is illegal for human consumption in the U.S. due to its hazardous health effects, and anyone buying the drug online should exercise extreme caution. While some may take the risk because of the less harmful side effects, they should always consider clenbuterol’s potentially extreme side effects. Last medically reviewed on August 11, 2022Alcohol / Addiction / Illegal DrugsObesity / Weight Loss / FitnessPharmacy / PharmacistSports Medicine / Fitness 8 sourcescollapsedMedical News Today has strict sourcing guidelines and draws only from peer-reviewed studies, academic research institutions, and medical journals and associations. We avoid using tertiary references. We link primary sources — including studies, scientific references, and statistics — within each article and also list them in the resources section at the bottom of our articles. You can learn more about how we ensure our content is accurate and current by reading our editorial policy.China battles pork meat laced with a poisonous drug. (2011).https://www.allaboutfeed.net/animal-feed/feed-processing/china-battles-pork-meat-laced-with-a-poisonous-drug/Clenbuterol [Fact sheet]. (2019).https://www.deadiversion.usdoj.gov/drug_chem_info/clenbuterol.pdfDaubert, G. P., et al. (2007). Acute clenbuterol overdose resulting in supraventricular tachycardia and atrial fibrillation [Abstract].https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3550084/Greydanus, D. E., et al. (2010). Sports doping in the adolescent: The Faustian conundrum of hors de combat.https://books.google.co.uk/books?id=uUri6XR1fk0C&pg=PA740&dq=latin+america+clenbuterol+asthma+medication&hl=en&sa=X&ved=0ahUKEwiJhdH6sJDXAhXHrxoKHeleDuMQ6AEIJjAA#v=onepage&q=latin%20america%20clenbuterol%20asthma%20medication&f=falseHuckins, D. S., et al. (2013). Myocardial ischemia associated with clenbuterol abuse: Report of two cases [Abstract].https://pubmed.ncbi.nlm.nih.gov/22633759/Prohibited list. (n.d.).https://www.wada-ama.org/sites/default/files/prohibited_list_2018_en.pdfSalleras, L., et al. (1995). Epidemiologic study of an outbreak of clenbuterol poisoning in Catalonia, Spain. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1382130/Spiller, H. A., et al. (2013). A descriptive study of adverse events from clenbuterol misuse and abuse for weight loss and bodybuilding [Abstract].https://www.ncbi.nlm.nih.gov/pubmed/23844963FEEDBACK:Medically reviewed by Alan Carter, Pharm.D. — By Tom Seymour — Updated on August 11, 2022 Latest newsWhat sets 'SuperAgers' apart? Their unusually large neuronsOmega-3 may provide a brain boost for people in midlifeSeasonal affective disorder (SAD): How to beat it this fall and winterCDC: Monkeypox in the US 'unlikely to be eliminated in the near future'Why are more women prone to Alzheimer's? New clues arise Related CoverageAnabolic steroids: What you should knowMedically reviewed by Alan Carter, PharmD Steroids are used in medicine to treat certain conditions, such as inflammation and hypogonadism. 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