Clen 40: Usage, Safety, and Effects for Weight Loss and Performance Enhancement.

The Food and Drug Administration (FDA) hasn’t approved clenbuterol for use in humans. A liquid form of the drug is approved by the FDA for treatment of airway obstruction in horses.

Outside the United States, clenbuterol is available by prescription only for the treatment of asthma. It’s also sometimes prescribed for the treatment of chronic obstructive pulmonary disease (COPD).

Clenbuterol isn’t a steroid, but it has properties similar to anabolic steroids, such as promoting an increase in muscle mass. Due to these properties, clenbuterol has been used in livestock to increase the amount of lean muscle.

The drug can still be found in the meat of livestock after it has been butchered, and this has led to illness in Europe and Asia. Because of this, the United States and Europe monitor tissue samples from livestock in order to detect the presence of clenbuterol.

Clenbuterol has also been observed as an additive in illegal drugs, such as heroin.

Clenbuterol has been observed to both increase muscle mass and reduce body fat. Additionally, it remains in the body with an active effect for about 6 days after consumption (detectable traces can remain longer). Because of these properties, it’s often used as a weight loss supplement or to enhance athletic performance.

People taking clenbuterol for weight loss or performance enhancement often use anabolic steroids or growth hormones as well.

Studies on the efficacy of clenbuterol as a weight loss or performance enhancer in humans are quite limited, although many studies have been performed in animals and livestock:

• Researchers have observed that clenbuterol stimulates muscle growth and repair while preventing atrophy in mice and rats.
• Studies in livestock have indicated that the increase in muscle growth occurs at the expense of fat tissue. This is part of a process referred to as repartitioning.
• A study horses found that long-term administration of high doses of clenbuterol increased the expression of genes related to various muscle components and fat metabolism.

Even though there is minimal evidence for clenbuterol as a performance-enhancing drug, it’s listed on the World Anti-Doping Agency’s Prohibited List.

Clenbuterol can have side effects when overused or misused. These can include:

• increased heart rate
• rapid breathing
• heart palpitations
• chest pain
• tremors
• anxiety
• electrolyte imbalance

A review of adverse reactions to clenbuterol reported to two poison control centers found that 11 of the 13 cases were due to clenbuterol use for weight loss or bodybuilding