How clenbuterol works
Clenbuterol is a drug from the group of beta-sympathomimetics. It activates certain binding sites of messenger substances in the lungs – the so-called beta-2 receptors). In response to this signal, the bronchi dilate. This effect is desirable in certain lung diseases.
In addition, clenbuterol is used in obstetrics as a reliable labor-inhibiting agent. By inhibiting labor, premature birth can be prevented. This gives the baby more time to develop in the womb.
Clenbuterol also acts to some extent “off-target” (i.e. away from the actual target = the lungs) on metabolism, muscle building and fat burning. Therefore, it can be misused as a doping agent in sports.
Absorption, degradation and excretion
After ingestion, clenbuterol is quickly and completely absorbed into the blood. The effect occurs after five to 20 minutes and lasts for about 14 hours.
The highest blood levels are reached after two to three hours. The active substance leaves the body unchanged and after 34 hours half of it is excreted mainly in the urine (half-life).
When is clenbuterol used?
Due to the long half-life, the full effect of clenbuterol is not expected until the fourth day.
Clenbuterol is also used in combination with the expectorant ambroxol to treat bronchitis (inflammation of the bronchi) with increased mucus production. It is used especially in cases of severe bronchial spasms (bronchospasms) with associated shortness of breath.
How clenbuterol is used
For symptomatic treatment of asthma and COPD, physicians usually prescribe clenbuterol in the form of tablets taken twice daily. At the beginning of treatment, they usually choose a higher dosage until symptoms improve.
The single dose for adults and children twelve years and older is between 0.02 to 0.04 milligrams of clenbuterol (equivalent to one tablet in the morning and one in the evening). The maximum daily dose is 0.1 milligrams of clenbuterol (= 5 tablets).
Note that clenbuterol does not act in time in acute attacks with constriction of the airways. In this case, an emergency spray with a fast-acting agent is necessary!
For bronchitis, combination preparations of clenbuterol and ambroxol are also often used in tablet form. Adults and children over the age of twelve usually take one tablet in the morning and one in the evening. The total number of tablets taken per day should not exceed four.
What are the side effects of clenbuterol?
Common side effects of clenbuterol are tremor, headache, restlessness, nausea, and palpitations.
Occasionally, undesirable side effects include dizziness, muscle pain and cramps, nervousness, itching, heartburn, rapid heartbeat, irregular heartbeat, high or low blood pressure, and problems with urination.
Most side effects occur especially at the beginning of therapy and disappear as treatment continues.
If you experience allergic skin reactions to clenbuterol, please notify your doctor or health care professional!
For information on less common side effects, see the package leaflet that came with your clenbuterol medicine. Contact your doctor or pharmacist if you suspect any unwanted side effects.
When should you not take clenbuterol?
You should generally not use clenbuterol:
- if you are hypersensitive to the active substance or to any of the other ingredients of the medication
- in severe hyperthyroidism (overactive thyroid gland)
- in cardiac arrhythmias
- hypertrophic obstructive cardiomyopathy (hereditary disease of the heart)
These drug interactions are possible with clenbuterol
- Theophylline (reserve drug for asthma and COPD)
- Ipratropium (drug for asthma and COPD)
- Salmeterol and formoterol (bronchodilators)
- Budesonide and ciclesonide (cortisone derivatives)
Concomitant use of beta-blockers such as metoprolol, bisoprolol, and propranolol attenuates the antiasthmatic effect of clenbuterol.
Clenbuterol may cause blood glucose levels to rise. Therefore, in diabetics, it may be necessary to increase the dosage of oral blood sugar medications (antidiabetics) or the amount of insulin for the duration of clenbuterol treatment.
Clebuterol in children
Child-directed formulations of clenbuterol (e.g., juice) in solid combination with the active ingredient ambroxol may be used from birth.
Clenbuterol: pregnancy and lactation
Data to date do not indicate an increased risk of malformation in unborn children. As a precaution, however, experts advise against the use of clenbuterol in pregnant women. However, the active ingredient can be used in the days before birth to inhibit contractions and thus delay the birth. However, this must then be monitored by a doctor.
Clenbuterol passes into breast milk. Breastfed infants should therefore be monitored for any symptoms if the mother is taking the drug. If necessary, switch to bottle feeding.
Clenbuterol and fertility
Whether clenbuterol affects human fertility has not been investigated in studies to date. However, there have been studies in animals. These provided no evidence that the drug negatively affects fertility in any direct or indirect way.
How to obtain medication containing clenbuterol
Clenbuterol in any dosage with or without ambroxol requires a prescription in Germany and Austria and can only be obtained with a prescription through a pharmacy.
There are currently no preparations containing clenbuterol registered in Switzerland.
