I have a young patient who developed serum sickness like reaction after Augmentin. I see older questions from 2014 which note a lack of knowledge on cross-reactivity. At this point, what is the current recommendations with regards to other penicillins as well as cephalosporins? Does he need to avoid all of these drugs moving forward?


If it truly was serum sickness after amoxicillin clavulanate, I would recommend avoiding amoxicillin clavulanate for at least the next several years. After 2-3 years, an oral amoxicillin 250 mg challenge and 5 days of observation would be a safe way to determine current tolerance. There is no good data regarding the need to avoid other non-amino penicillins in the setting serum sickness. If another penicillin was needed it would probably be safe to do an oral penicillin 250 mg challenge with 5 days of observation. There is no need to avoid cephalosporins.

I hope this information is of help to you and your patient.

Eric Macy, MD, MS, FAAAAI

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