Botox (onabotulinumtoxinA) is Allergan’s trade-name for the protein and neurotoxin that is most commonly used for frown lines (between the brows) and crow’s feet, which emerge over time as a result of repeated facial muscle contraction. Botox is used cosmetically by injecting a designated facial muscle with a specific number of units to diminish dynamic movement. As we age, skin loses its collagen and elastin, and dynamic wrinkles begin to form from repetitive movements like frowning. Botox is an effective treatment for subtly smoothing the appearance of skin lines and wrinkles. It also prevents new lines from forming.  Botox begins to work in 3-5 days with a full onset at 2 weeks, with its effects lasting 3-4 months.