First case of anaphylaxis after botulinum toxin type A injection.

Botulinum toxin type A (BTA) (also known as onabotulinum toxin A) injection is widely used in the field of cosmetic dermatology. Although a few adverse events related to intramuscular BTA injection have been reported, no life-threatening adverse reaction has been documented to date. We report a case of anaphylaxis induced by intramuscular BTA injection into the masseter muscles of a 35-year-old woman. She had previously received injections of the identical BTA product into the same muscles without incident. However, during the reported procedure, symptoms suggestive of angio-oedema and anaphylaxis developed about 5 min after BTA injection. Intramuscular epinephrine was used to manage the reaction. Following this, the patient was found to have an elevated total serum IgE level. We could not perform testing with BTA because of the risk of triggering another episode of anaphylaxis; however, intradermal tests using the identical sterile saline and patch test using the topical anaesthetic cream both showed negative results, thus we strongly suspect BTA as being the cause of anaphylaxis in this case.