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You are seeing an 8 year old girl who was prescribed an oral cephalosporin antibiotic 1 week ago for rhinitis. She has 3 more days until she finishes the course. Now she has developed an itchy urticarial-like rash, although it is more fixed than urticaria typically are (does not move around nor come and go). She also has some generalized mild arthralgias and a low-grade fever to 100.2 F.
May 18, 2022 at 3:07 pm
C) Stop the antibiotic
The symptoms described are consistent with a serum sickness-like reaction (SSLR). The most common causes are beta-lactam antibiotics, especially amoxicillin and cefaclor, and trimethoprim-sulfamethoxazole. SSLR has similar symptoms to true serum sickness, which is mediated by the formation of immune complexes (type III hypersensitivity). True serum sickness is associated with animal-derived anti-toxins and immune modulators, some vaccines, and some insect stings. Stopping the offending agent is often the only treatment needed. Mild to moderate symptoms can be treated with antihistamines and NSAIDs, and severe symptoms often respond to a short course of oral corticosteroids.