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What are Clenbuterol® Side Effects?

By Dulce Corazon
Updated Jan 31, 2024
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Clenbuterol®, also known as Clen, is a bronchodilator and beta-agonist that is primarily used to treat breathing disorders or lung diseases such as asthma. It is, however, also widely used as a weight-loss supplement or bodybuilding supplement. This drug, which also acts as a decongestant, causes the body to burn body fat to use as energy, resulting in increased body temperature. There are several Clenbuterol® side effects that may manifest themselves when someone is taking this drug, including elevated blood pressure, insomnia, muscle cramps, and excessive sweating.

One of the side effects that affects both men and women is high blood pressure. This drug acts as a stimulant, so it has the tendency to increase a person's heartbeat, which may result in the elevation of blood pressure. It should not be used by anyone who has hypertension or high blood pressure.

Another of the side effects of taking this drug is insomnia, where an individual has difficulty falling asleep. This is due to the stimulant effect of Clenbuterol®. Individuals taking it and at the same time consuming greater amounts of caffeine frequently experience severe insomnia.

This drug can affect the central nervous system, causing an individual to sweat excessively. Women may experience more intense sweating at some point in their hormonal cycle. According to some users, however, sweating is an expected Clenbuterol® effect and is a sign that the drug is working. Other side effects include nervousness, nausea, muscle tremors, and heart palpitations. After a week or more of taking the drug, some individuals may become used to it, thereby gradually reducing the number of side effects.

Clenbuterol® has been used by athletes and bodybuilders as it may help build bigger muscles. Short-term use frequently helps them to lose body fat and increase muscle mass before a competition. Athletes are frequently advised to use the medication for only a short period, which is about two to three weeks. Longer term use can lead to heart damage or heart failure.

There are several contraindications to the use of Clenbuterol®. It must not be taken by individuals suffering from cardiac rhythmic disturbances or those with cardiovascular diseases. Pregnant women are advised against taking this drug. Some countries also consider its use illegal; it is not approved for use by humans in the US. Several international sporting agencies list it as a performance enhancing drug.

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Discussion Comments
By anon347606 — On Sep 08, 2013

One side effect not often mentioned- sudden death due to heart failure. My 33 year old brother died in his sleep less than one week after stating clenbuterol. I miss him every day.

By anon291202 — On Sep 13, 2012

I took a course of Russian based Clen just over a year ago, I am 43 and I have been training all my life with bodybuilding, karate and running which helped me live through a road accident 12 years ago that caused collapsed lungs, severe cranial and "profound" brain damage (my left eye was destroyed) as well as nearly losing my left foot & having severe lower leg fractures (I was hit head-on in my sports car by an idiot driver).

Taking a strong fitness lifestyle into consideration and recovering beyond all expectations, I took Clen to assist in weight loss with my gym training as I can't run anymore due to ankle damage. I noticed some chest aches, being out of breath at times and palpitations (which I put down to the death of my mum and a long term relationship ending), but I did lean up a little while on Clen. I had an ECG last month and the results showed I have had a heart attack at some point - a mycardial infarct (surprising shock as I didn't realize any obvious symptoms). I now wonder if Clen was the cause.

By Monika — On May 31, 2012

I'm not surprised that Clenbuterol isn't approved for use in humans in the United States. There are a lot of other drugs that can be used for asthma and other breathing disorders that don't have such pronounced side effects.

Other people have mentioned Albuterol inhalers. There are also steroid inhalers as well as oral medications for asthma, both of which don't have as many side effects as Clenbuterol does.

When you take the insomnia side effects and the heart palpitations caused by Clenbuterol into account, it doesn't really seem worthwhile to take this drug. Especially when there are so many other alternatives.

By JessicaLynn — On May 30, 2012

@strawCake - I use Albuterol also, and I too hate the shaky hands and the racing heart that comes with using it. However, being thin is highly prized in our society, and I've heard of people exposing themselves to even worse side effects to try and lose weight.

Like the article said, some people use Clenbuterol, even though it can be dangerous. I've also heard of people using drugs that have been pulled of the market because they can cause serious, permanent side effects and even death! It is really crazy.

By strawCake — On May 29, 2012

I've had asthma all my life, but to the best of my knowledge I've never taken Clenbuterol. In fact, I've only ever heard of Clebuterol in the context of fat burners! I've been using an Albuterol inhaler for quite some time though.

Interestingly enough, Albuterol is also a bronchodilator and beta-agonist. And the side effects sound pretty similar. However, the side effects from Albuterol go away fairly quickly, while it sounds like the side effects from Clenbuterol can linger for quite some time.

I can't imagine voluntarily subjecting myself to those side effects if I didn't need the drug for my health!

By anon137800 — On Dec 29, 2010

can clenbuterol could have a bad effect on the male reproductive organ?

By anon94585 — On Jul 09, 2010

Very informative post. Clenbuterol can be purchased online.

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