One of the most popular procedures requested to treat wrinkles is the injection of Botulinum Toxin Type A into facial muscles. Wrinkles are caused by repeated contraction of the muscles of expression, resulting in horizontal forehead lines, frown lines or crow’s feet. By injecting extremely small amounts of botulinum toxin under the skin, the target muscle weakens and the creases soften and gradually disappear . Relaxation of the injected muscles lasts for three to six months initially, and another session is required.  However, after several treatments, the effect lasts longer.