The first option, which is most appropriate for active lines or age associated wrinkles that are just starting to appear, is to temporarily weaken or paralyze the muscle that is causing the wrinkle.
Botulinum Toxin type A is a family of neurotoxins that block nerve signals that cause muscles to contract. The toxin works directly where it is placed, and thus can be artistically used to alter facial expressions. Botox Cosmetic® is widely recognized, and was the first neurotoxin to be approved for cosmetic use in the United States. Other manufactures are producing variant toxins that will likely be approved for use in the near future, including Reloxin and PurTox. These toxins will be differentiated by their time to onset, duration of effect (the clinical effects of Botox Cosmetic® are typically 3 to 4 months), and the distance of effect from the injection site.
Risks include bruising at the injection site, rare chance of an infection, and the possibility of unintentionally affecting nearby muscle groups. Specific risks should be discussed with your physician when considering treatment.