Pittsburgh botox centers are full of knowledgeable doctors and medical professionals that are extremely qualified to deliver the anti-aging injections. So, how does botox work? In short, the localized injections relax the muscles of the face, causing wrinkles around the eyes and smile lines around the mouth to fade away. How long does botox last? Typically, up to about four months or so, which is why fans of the treatment get injections on a regular basis. As for the side effects of Botox, they often include mild redness, bruising, and swelling.