neurotoxin. It targets the nervous system and interferes with the signals that stimulate muscle contraction, which is why it causes temporary muscle relaxation.

For a muscle to contract, nerves release a chemical messenger called acetylcholine at the junction where nerve endings meet muscle cells. Acetylcholine binds to receptors on the muscle cells, causing them to contract.

Botulinum toxin injections block the release of acetylcholine, preventing muscle contraction. In this way, the toxin helps reduce muscle stiffness and smooth out wrinkles.