For more than 20 years, therapeutic botulinum toxin A has been applied with success. With this long experience, the substance can viewed as safe and low in side effects. This was confirmed by a recent meta-analysis of placebo-controlled clinical studies. The side effects documented were light to moderate, temporary, and local. In respect to the frequently needed long-term therapy, it is necessary that botulinum toxin A be safe and cause no disturbance. The development of neutralizing antibodies to botulinum toxin A is very rare and no longer has an appreciable effect on its clinical application.