Serum Sickness After Cosmetic Botulinum Toxin Type A Injections

Botulinum toxin type A (BoNT-A) is widely used in therapeutic and cosmetic settings for neuromuscular and aesthetic indications. Although generally well tolerated, reports of hypersensitivity reactions—ranging from localized erythema to systemic immune syndromes— underscore its immunological complexity. This case report and literature review demonstrates a novel case of serum sickness following cosmetic Botox® (onabotulinumtoxin-A) administration, categorizes hypersensitivity reactions according to the Gell and Coombs classification (Types I–IV), explores the role of complexing proteins and formulation excipients, and highlights emerging clinical concerns. This will underscore the need for greater vigilance in identifying systemic immune responses to BoNT-A especially within the cosmetic medicine industry.