Pharmaecutical botulinum toxin is able to temporarily block transmission of nerve impulses to the muscles. When it reaches nerve endings and is absorbed, it temporarily inhibits liberation of a neurotransmitter that causes muscular contraction. Thanks to the Carruthers brothers, who first studied its cosmetic effects in 1922, today more than 10 million botulinum toxin treatments per year are carried out all over the world. When it is injected through very small thin needles, it spreads out across a 1cm diameter, causing progressive muscular paralysis for a period of at least 4 months. The clinical effect is dependent upon dose and site. The effect can be complete muscular paralysis, or just a reduction in contractility. This dose/site-dependency means that the results can be modified according to the characteristics of the individual patient. Localised muscular paralysis causes reduction or disappearance of wrinkles, and treatment of depressor muscle groups while leaving levator groups intact also enables a lifting effect to be achieved in some facial areas. Botulinum toxin is also used very successfully in treatment of hyperhidrosis (above all underarm, palms and soles) and some rare syndromes such as Frey’s Syndrome, Crocodile Tears syndrome etc.