It inhibits the secretion of neurotransmitter (Acetylcholine) that causes muscle contraction, causing flaccid paralysis of muscles. This toxin, which is used for the purpose of treating neurological or muscular diseases by locally paralyzing only the muscles of the injected area, is diluted to a safe concentration and injected into the muscles to paralyze facial expression muscles, thereby improving facial wrinkles. Thick wrinkles on the face are caused by contraction of facial expression muscles, and botulinum toxin can be injected into these muscles to suppress the action of nerves that cause muscle contraction, thereby smoothing out wrinkles.