Botox, short for Botulinum toxin, is a neurotoxin produced by the bacterium Clostridium botulinum. When injected into specific muscles in very small, controlled doses, Botox works by blocking the release of a neurotransmitter called acetylcholine. Acetylcholine is responsible for sending signals from nerves to muscles, causing them to contract. By blocking this signal, Botox effectively relaxes the muscle, reducing its activity.

Common side effects include temporary bruising at the injection site, headaches, and, rarely, unintended muscle weakness near the injection site. In some cases, more severe side effects like difficulty swallowing or breathing can occur, particularly if the toxin spreads beyond the target area.

The effects of Botox are temporary, typically lasting 3 to 6 months. As the muscle activity gradually returns, wrinkles or symptoms may reappear, requiring repeat treatments.