Excipient-Induced Hypersensitivity: A Case Study and Review

A 23-year-old female presented with a unilateral neck lump, raising suspicion of lymphoma. Empirical treatment with Brand 1 (amoxicillin/clavulanic acid) 625mg BD was given without adverse effects. However, after switching to Brand 2, the patient developed a hypersensitivity reaction, including urticaria and itching on the palms and soles. This was attributed to an excipient difference between the brands. Antibiotic therapy was stopped, and the patient was treated with methylprednisolone, levocetirizine, and calamine lotion. This case highlights the importance of excipients in hypersensitivity reactions and emphasizes the need for standardized excipient lists and labelling in the medication.