Botulinum toxin is a naturally occurring substance produced by Clostridium botulinum.¹ When injected, the toxin works as a muscle relaxant, temporarily weakening the activity of targeted muscles. It achieves this by blocking the transport of the neurotransmitter acetylcholine across the neuromuscular junction, located between the nerve end and the muscle fiber.

The mode of action of botulinum toxin involves four main stages, all of which must function correctly for activity to occur. The effects of botulinum toxin last until the junction has recovered and muscle activity returns.²