Botox is the pharmaceutical drug best known for smoothing out wrinkles, and it’s used by millions of people. Botulinum toxin A is a neurotoxin that works by paralyzing parts of the body. It was first used as a potential treatment for muscle disorders, says Business Insider. Not only is Botulinum toxin A a deadly toxin — it’s the deadliest one on Earth. In small doses though it freezes signals from the nerves to the muscles which causes wrinkles to relax.