Injectables are commonly used to treat dynamic wrinkles. Dynamic wrinkles include the forehead lines, fine lines around the eyes, and the furrows between the eyebrows. Injectables work by weakening the muscles of facial expression that insert onto the surface of the skin. Weakening the pull of these muscles on the skin causes the visible wrinkles to flatten out. Over time, injectables can reduce wrinkles caused by the pull of facial muscles.