Botox

Botox is an inactivated protein neuro-toxin from the bacterium, botulinum that is injected into the skin with a small, fine needle.

How it works: The toxin binds to the receptors on the muscles, thereby blocking them. Thus the muscle cannot receive the message from the nerve to contract. Without contraction, the lines relax. They may not fully relax after one treatment if the lines are very deep (remember the muscle has been contracting for years), but after several treatments in succession the lines usually fully relax.