The injection of botulinum neurotoxin (BoNT) for cosmetic purposes is the most commonly performed cosmetic procedure in the USA, with 4 million such procedures performed in 2011 alone (American Society for Aesthetic Plastic Surgery, 2011).
With time, overlying skin loses both its elasticity and thickness. This, coupled with repeated pleating and contraction of the skin over many years, will result in wrinkles. Cosmetically, the primary function of BoNT is to paralyze the muscles of facial expression. By relaxing the relevant underlying muscles of facial expression, BoNT will eliminate the so-called “dynamic” rhytids (wrinkles). Over time, even the appearance of static rhytids may be improved. In a 2007 study, patients reported looking 3 years’ younger than baseline 4 weeks after receiving BoNT to the upper face (Carruthers and Carruthers, 2007)
Currently (2012), there are three BoNT type A (BoNT-A) formulations with a cosmetic indication available in the USA: onabotulinumtoxinA (Botox, Allergan. Irvine, CA, USA), abobotulinumtoxinA (Dysport, Ipsen, Slough, UK) and incobotulinumtoxinA (Xeomin, Merz, Frankfurt/M, Germany). All are approved for the treatment of glabellar lines.