Botulinum toxin is a neurotoxic protein produced by the bacterium Clostridium botulinum.
It is one of the most poisonous naturally occurring substances in the world.
Though it is highly toxic, it is used in minute doses both to treat painful muscle spasms, and as a cosmetic treatment in some parts of the world.
It is sold commercially under the brand names Botox and Dysport for this purpose.
The terms Botox and Dysport are trade names and are not used generically to describe the neurotoxins produced by Clostridia species.
Researchers discovered in the 1950s that injecting overactive muscles with minute quantities of botulinum toxin type A decreased muscle activity by blocking the release of acetylcholine at the neuromuscular junction, thereby rendering the muscle unable to contract for a period of 4 to 6 months.