Wrinkles on the face are caused by using certain muscles in a consistent pattern over a long period of time, such as squinting and frowning. By the time we are 30 or 40, these wrinkles are well-established. Botox (the household name) and its newer equivalents, Xeomin and Jeuveau, do their job of eliminating wrinkles by making the underlying facial muscles unable to contract. Without muscle contraction, wrinkles can’t form. It’s that simple.