Urticaria-Like Hypersensitivity Reaction Following Botulinum Toxin Injection: A Case Report of Possible Interaction with β-Lactam Antibiotics.

Botulinum toxin serotype A (BTX-A) is commonly used for treating facial dynamic wrinkles. The clinical safety of BTX-A has been proven, and it has few side effects; despite this, BTX-A has the potential to cause an allergic reaction. This case raises concerns about a possible interaction between botulinum toxin serotype A (CBTX-A) and β-lactam antibiotics, contributing to the limited literature on hypersensitivity reactions. Herein, we described the case of a 35-year-old woman who was injected with Chinese botulinum toxin serotype A (CBTX-A) to treat crow's feet. The treatment was performed after the patient had taken cefprozil for an upper respiratory tract infection. Subsequently, the patient developed urticaria-like symptoms that completely resolved within 24 hours after administration of antihistamines. This case emphasises the need for careful medication history review before botulinum toxin administration, especially in patients receiving β-lactam antibiotics, as hypersensitivity reactions may occur.