Anti-wrinkle injections work by preventing nerves from carrying an electrical message from the brain to the muscle. In the diagram below you can see the anti-wrinkle product sitting at the end of the nerve and prevents the release of a chemical called acetylcholine. This prevents the muscle from contracting.
It takes time (usually between 5 and 14 days) for the anti-wrinkle product to make its’ way to the end of all the individual nerves and for it to block the release of acetlycholine. As it blocks more and more acetylcholine the effects of the injections become more noticeable.
A video showing the effect of anti-wrinkle injections over time