The Use of Botulinum Toxin Type A and the Occurrence of Anaphylaxis: A Descriptive Analysis of Data from the European Spontaneous Reporting System.

[BACKGROUND] Botulinum toxin type A (BTA) is a protein produced by Clostridium botulinum bacteria. It is the most widely used among botulinum toxin types, and it is recommended for the treatment of many clinical conditions, including muscle hyperactivity syndromes and for esthetic indications too. BTA is generally considered safe, and the most reported adverse events (AEs) include eyelids ptosis, immunogenicity, neuromuscular disorders and hypersensitivity reactions. In addition, serious idiosyncratic AEs, such as anaphylactic shock, have been highlighted.

[OBJECTIVE AND METHODS] Taking into account that BTA skin toxicity has been already investigated recently by our research group and that, in many cases, the BTA-induced skin toxicity represents a symptom of an hypersensitivity reaction, the aim of the present study was to better characterize cases of anaphylaxis occurring after intramuscular administration of BTA by analyzing Individual Case Safety Reports (ICSRs) sent to the EudraVigilance database.

[RESULTS] A total of 86 ICSRs, covering 449 Preferred Terms, reporting BTA as suspected drug and "anaphylactic reaction," "anaphylactic shock," "anaphylactoid reaction" or "anaphylactoid shock" as ADR were suitable for our analysis. The majority of patients who experienced BTA-induced anaphylaxis were female (89.5%) and mostly belonged to the age group 18-64 years. The most common outcome was "recovered/resolved," while the seriousness criteria was mostly reported as "caused/prolonged hospitalization."

[CONCLUSION] Our results showed that anaphylactic reactions may occur after esthetic use of BTA; thus, a close monitoring before, during and after BTA intramuscular injection is highly recommended in order to prevent the occurrence of this event and ensure an appropriate management of the patients receiving this drug.

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