Both of these drugs fall into the category of neuromodulators. That means they help to improve wrinkles that develop with muscle activity. How they work is very scientific and difficult to understand (deals with synapses, vesicles, neuromuscular junctions, etc.). Therefore, I would like to simplify this. Consider that your brain sends a signal to a muscle for that muscle to contract. BOTOX acts like a crossing guard. When it is present, it blocks that signal and the muscle will not contract so you see an improvement in the wrinkles caused by the muscle. The body works around this by "building a new road" which bypasses that crossing guard. This process takes about 3 months which is why that is how long BOTOX and Dysport work.