Mild Allergic Reactions after Botulinum Toxin Injection: A Case Series and Literature Review.

Background: Botulinum toxin type A (BTA) is becoming more and more prevalent as an injection agent in cosmetic surgery. However, there is an increasing amount of cases reporting unexpected adverse reactions related to BTA injection. BTA can invoke many kinds of hypersensitive reactions, some of which can be delayed-type or even fatal; hence, it is of crucial importance to pay close attention to atypical and early symptoms that may indicate the presence of BTA allergy in patients. Methods: In this study, we reported three cases of mild and unexpected BTA-related hypersensitive reaction with a symptom of nonpruritic erythema on the chest that happened after BTA treatment of upper facial wrinkles and proposed several suggestions based on our practical experience and literature review. Results: Two patients' symptoms were alleviated spontaneously, and one patient's were alleviated after taking oral corticosteroid. According to our literature review, we believe that these incidences indicate a kind of unreported allergic reaction relevant to botulinum toxin. Conclusions: We suggest clinicians consider warily patients' subsequent BTA injection schedule if any suspicious reaction occurs after treatment. We suggest that patients who experience nonpruritic erythema after botulinum toxin injection should suspend subsequent injection plans for at least 3 months to prevent more severe consequences.