Clenbuterol is a drug known as a sympathomimetic amine. It is a decongestant (thins the blood to reduce blood pressure) and a bronchodilator (widens the blood vessels so the volume of oxygen in the blood increases).

Clenbuterol stimulates both the heart and central nervous system, and has been compared in its effects to stimulants such as epinephrine and amphetamines. It is a beta-2 antagonist, which is opposite in action to a beta blocker. Clenbuterol increases the production of epinephrine and noradrenaline whereas beta blockers reduce it.

Its effects also include increased body temperature and heart rate leading to a faster metabolism, which is why it has become popular as a drug for weight loss.

What is Clenbuterol Originally Used For?

Clenbuterol is used to treat allergic respiratory disease in horses thanks to its qualities as a bronchodilator, and can also be used to relax the uterus of cows during the birthing process.

For those taking the drug for asthma treatment, the standard recommended dosage is 0.02-0.04mg per day or as prescribed and supervised by a qualified doctor.

It is also used in some countries to treat asthma in humans and has been used illicitly as a weight loss substance. It has been favored in recent years by bodybuilders looking to lose fat while maintaining their lean muscle and it has been sold online without prescription, often leading to problematic effects. Some people have used Clenbuterol for weight loss and experienced minor side effects without major health problems; however this is down to the individual’s health and tolerance and should not be taken as an indication that it is safe to do so.

Those taking Clenbuterol for weight loss often do so in cycles, taking the drug on consecutive days for up to a week before having a period without it. People taking Clenbuterol for weight loss also often ‘taper up’ to their maximum dose of the drug and ‘taper down’ as they come off it in an attempt to minimize the side effects; this is not always effective.

How Does Clenbuterol Work For Weight Loss?

Clenbuterol treats asthma and respiratory diseases by opening the blood vessels and allowing a higher volume of oxygen to flow around the body to make up for the lack of oxygen intake caused by breathing problems.

When considering Clenbuterol as a weight loss drug it is important to know that it boosts your body’s internal temperature, leading to a related increase in metabolism. This encourages your body to use stored fat as energy, leading to weight loss. Thanks to the dilation of blood vessels, Clenbuterol in the short term may also increase the amount of time that consumers can train for and the intensity of the training, so further weight loss can be achieved from intense exercise. The drug will also shift water weight as it acts as a diuretic, so consumers will see weight loss from several of Clenbuterol’s actions.

How Do You Take Clenbuterol For Weight Loss?

Those taking Clenbuterol for weight loss may consume it in several forms. These include orally in capsule or liquid form; as injections or as an ingredient in a nasal spray.

The Benefits of Taking Clenbuterol For Weight Loss

People who use Clenbuterol for weight loss are likely to see the results more quickly than those who take other diet pills, due to the strong and rapid effects of the drug.

On days one to four of taking the drug, people have reported a noticeable shift in excess water and related water weight, leading to reduced bloating.

On days two to seven of taking Clenbuterol, you may find yourself feeling hotter than usual due to your increased metabolism. You may also have a suppressed appetite and increased energy; great for longer cardio sessions in the gym!

On days eight to fourteen of taking the drug you may have lost two to five pounds and possibly retained lean muscle mass.

These benefits are subject to the consumer experiencing no side effects such as stroke, arrhythmia or enlarging of the heart. The side effects often make consumers ill enough to have to take time off work or to stop their exercise program, leading to them regaining the weight when they stop the drug.

The Risks of Taking Clenbuterol for Weight Loss

The side effects of taking Clenbuterol for weight loss are extensive and severe; there have been deaths linked to the drug. It is for this reason that Clenbuterol is labelled as unfit for human consumption by the FDA and is illegal to purchase without a prescription.

Medical side effects of consuming Clenbuterol for weight loss include:

  • Depression and low mood
  • Heart problems including palpitations and arrhythmia
  • Insomnia and other problems getting to sleep or staying asleep
  • Excessive diarrhoea and stomach cramps
  • Stroke
  • A dry mouth and dehydration
  • Vomiting
  • Overheating (hyperthermia) and excessive sweating
  • Death, usually from related heart problems
  • In the case of Clenbuterol injections, scarring or potentially lethal air bubbles in the blood
  • In the case of Clenbuterol tablets, liver damage
  • It is also common once users stop taking Clenbuterol for weight loss to regain all the weight that they initially lost, as the drug is not part of a sustainable weight loss program or healthy lifestyle.

A study into the physical effects of Clenbuterol showed that using Clenbuterol regularly actually decreased physical stamina and endurance by degrading the heart structure, and some of the test subjects died from heart failure. These effects were present after just one injection of Clenbuterol, indicating that any dose of the drug can be harmful and no dose is risk-free.

One study on the effects on fertility of taking Clenbuterol for weight loss found that the portion of the testes that is responsible for testosterone production increased. However, the testes cells where sperm is manufactured was permanently damaged, suggesting that Clenbuterol may adversely affect fertility.

Clenbuterol takes an extended time to degrade within the body, meaning that its effects can be accumulative and that users are left unaware of how much is being processed in their body at any one time.

What The Law Says – Risks of Importing Clenbuterol

It may be tempting to import Clenbuterol from other countries where it is not regulated, for your own consumption and to help you lose weight. However this is strongly inadvisable for the following reasons:

  • Inaccurate labelling- language issues or poor quality control can lead to mislabelling of the imported product.
  • Unreliability of the product. Regulations in other countries may be weak and products may be counterfeit or ineffective.
  • Dirty or non-sterile production and unsanitary packing conditions could cause contamination and sickness.

There have been several deaths associated with taking Clenbuterol for weight loss and without a prescription. These include a previously fit and healthy rugby player in his twenties who took the drug to increase his metabolism, and died from cardiomyopathy- a condition where the heart cannot pump blood optimally due to a weakened and enlarged heart valve.

Should You Use Clenbuterol for Weight Loss?

Taking Clenbuterol for weight loss is not a good idea. It certainly has fat burning effects and weight loss potential but the damaging side effects are not worth the risk. Creating a healthy lifestyle for weight loss including regular exercise and balanced diet with a calorie deficit is the best way to lose weight in a sustainable and low-risk way. Even when Clenbuterol does cause weight loss in subjects, the side effects such as nausea and shaking can prevent an exercise routine from being followed, meaning that sustainable weight loss is not achieved.

What Are Some Clenbuterol Alternatives?

There are several safer alternatives to taking Clenbuterol for weight loss. These include natural ingredients that mimic the appealing effects of Clenbuterol such as suppressed appetite and increased energy and metabolism.

Garcinia Cambogia Extract– The extract of this tropical Indonesia fruit is known for its beneficial weight loss properties. Fans of Garcinia Cambogia Extract have found that it suppresses appetite and contains an ingredient called hydroxycitric acid (HCA) which blocks a fat-creating enzyme. It should be taken with caution due to potential side effects related to the liver.

Cayenne Pepper– This spicy ingredient has been linked to appetite suppression and has been claimed to be thermogenic, leading to a faster metabolism.

Citrus Aurantium– This thermogenic ingredient increases your body’s internal temperature, leading to an increase in calories burned and will also help your body to use stored fat as a primary energy source.

Nicotinamide– This helps your body to form two essential coenzymes that are important for energy synthesis and repair of the body’s DNA.

Guarana Extract– This plant from the Amazon is known for its ability to help people lose weight as well as giving a boost in energy from the stimulant guaranine.

There are also several synthetic pills you can take that mimic the effects of taking Clenbuterol for weight loss; two of the most popular are ‘Clenbutrol’ and ‘ClenXDV’.


We would recommend that you avoid using Clenbuterol for the purposes of weight loss – the risks for outweigh the benefits in our opinion, especially when there are so many other great OTC fat burner options available to consumers.

Marina Ma, MD
Marina Ma, MD
Staff Writer at DietProbe
Marina has an MD from U-M and is a resident writer and fact checker at DietProbe.
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