A protein is injected into the muscle to relax it by temporarily blocking the nerve impulses that cause the muscle to contract. This reduces or eliminates movement of the muscle the therefore the appearance of lines and can also prevent the formation of new wrinkles.
The effect usually takes place within three to seven days (up to 2 weeks) of treatment and lasts normally 3 to 4 months, up to six months in some.
New nerve endings develop over a three to six-month period, allowing the muscle action to resume.