When you squint or frown, the muscles between your eyebrows contract, causing the skin to furrow and fold. Over time, as your skin ages and loses some of its elasticity, these repeated contractions can cause persistent frown lines. Botulinum toxin type A – the active ingredient in Xeomin®– acts on nerve endings in muscles to prevent muscle fibers from contracting. By reducing these contractions, Xeomin® can temporarily reduce the lines between your eyebrows.