Botulinum toxin is a unique pharmaceutical agent in wide-scale use for cosmetic and multiple therapeutic applications. Physicians using these agents for esthetic purpose must realize the potential for future therapeutic needs. Because most indications require repeated injections, the recipient is at risk for immunologic reactions with possible formation of neutralizing antibodies. An individual who is injected with botulinum toxin for cosmetic purposes could someday require an effective form of type A toxin for dystonia, pain, or spasticity.