In cosmetic applications, botulinum toxin is considered safe and effective for reduction of facial wrinkles, especially in the uppermost third of the face. The effects of current botulinum toxin injections for glabellar lines (’11’s lines’ between the eyes) typically last two to four months and in some cases, product-dependent, with some patients experiencing a longer duration of effect. Injection of botulinum toxin into the muscles under facial wrinkles causes relaxation of those muscles, resulting in the smoothing of the overlying skin. Smoothing of wrinkles is usually visible three to five days after injection, with maximum effect typically a week following injection. Muscles can be treated repeatedly to maintain the smoothed appearance.