Botox, or botulinum toxin type A, is a protein neurotoxin derived from the bacterium Clostridium Botulinum, which acts locally in the muscles, temporarily blocking the transmission of nerve impulses from the nerves to the muscles. Thus, the affected muscles stop contracting and relax, causing the overlying skin to stretch, as a result the skin remains stretched and unlined while the untreated facial muscles continue to contract normally, allowing the person to remain with an unaffected facial expression. The skin will also take on a brighter colour as a result of local vasodilation with rich oxygenation of the skin.
Botulinum toxin type A has been used therapeutically for over 20 years for the treatment of strabismus, torticollis, facial spasm, bruxism and blepharospasm. Later botulinum toxin was used in the cosmetic treatment of facial expression lines