Dysport Repeated muscle contractions from frowning, squinting, or raising eyebrows cause the skin to furrow and fold, gradually resulting in the formation of facial lines. Neurotoxin injections work beneath the surface and temporarily reduce the underlying muscle activity that causes moderate to severe frown lines, crow’s feet, and forehead lines in adults – allowing them to relax and look visibly smoother. Neurotoxin Injections are not a permanent treatment. If you discontinue treatment the moderate to severe frown lines, crow’s feet and forehead lines will gradually return.