Overview of botulinum neurotoxins.

Dr Alan Scott's seminal investigations in the 1970s into the use of botulinum neurotoxin for strabismus represent the pivotal moment in its clinical research. In the decades that followed, botulinum neurotoxin was increasingly studied for therapeutic and aesthetic use. Currently, several botulinum neurotoxin products are available worldwide, with only a few investigated for cosmetic applications, and only one currently approved for facial aesthetic use in the United States. Comparisons among the agents are challenging due to a limited number of controlled studies. The few comparative studies published have contributed to a better understanding of the relative efficacy and safety of these products, but factors such as a broad clinical research experience, approved indications, and pharmacologic characteristics of each agent also influence choice of therapy. Issues such as botulinum neurotoxin resistance and selection of injection sites have also emerged as considerations for treatment selection. This article provides an overview of currently available botulinum neurotoxin products, including a review of key comparative aesthetic data and a discussion of issues related to botulinum resistance and injection site selection from leading experts in the fields of dermatology and plastic surgery.