In general, you will need Botox injections every 3 to 6 months. The determining factor is a combination of the dosage that you received at the time of your initial injection and how fast your body metabolizes the Botox. Botox functions by blocking the signal to contract the muscle that is causing the wrinkles in your face. Overtime, the body degrades the Botox molecule, the signal restarts, and you begin to move the muscles again.