This neurotoxin, derived from the bacterium clostridium botulinum (which causes botulism), is a therapeutic agent used in medicine to treat certain neuromuscular conditions. It is also used in medico-aesthetics. The botulinum toxin is manufactured in the laboratory under extremely well controlled conditions. When it is administered in small amounts, it is generally well tolerated and effective to treat many conditions associated with muscle hyperactivity disorder. 

Usually, our brain transmits electrical messages to our muscles allowing us to contract and move them. The electrical message is transmitted to our muscle through a substance called acetylcholine. Botulinum toxin blocks the release of acetylcholine, preventing muscle contraction. Thanks to these products, muscle spasms completely cease or fade greatly, providing safe relief from symptoms, including pain in some cases. 

Botulinum   toxin is injected into the affected muscle. Since it acts at the site of the spasm, it must be injected into the affected muscle using a very fine needle. 

Depending on the injection site, the effects can occur very quickly, i.e., in less than one or two days or can take up to two weeks. 

Following treatment, the effect will gradually develop  andusually persist  for three or four  months. There is, however, some individual variability; depending on the injection area, the degree of effect desired and the number of units injected. 

Probably the safest medical-aesthetic procedure. Butts drugs  can cause some side effects..  Those  associated with  botulinum toxin treatment  are generally transient and rather weak to moderate. Most of the time it  consists of: small  bruising, local pain, transient headaches. Rarely temporary asymmetry, sagging eyelid. These side effects are all transient