The recommended challenge test after negative penicillin skin tests is Amoxicillin not Augmentin. Amoxicillin plus clavulanic acid is often a better choice but now I find articles indicating that there are patients who may be allergic to the clavulanic acid component (JACI Feb 2010 vol.125 No.2 p502-505 Letters to the editor: Torres et. al. "Clavulanic acid can be the component etc. and JACI 2010 July Vol 126 No.1 page177-179 Sanchez-Morillas et al "Selective allergic reactions to Clavulanic acid: 9 cases). Is clavulanic acid available for testing? If a patient does well with Amoxicillin but reacts to the combination medication without specific testing I would suppose the full penicillin skin testing needs to be repeated with another Amoxicillin challenge? Do you have any thoughts on this and is this an issue for others?


We sought the expertise of Dr. Eric Macy. Please see his response below.

"If there is suspected hypersensitivity to clavulanic acid, because Augmentin was the antibiotic associated with the index reaction, and penicillin allergy testing with an oral amoxicillin 250 mg challenge was negative, then an additional oral challenge with amoxicillin/clavulanic acid 250 mg with 1 hour observation can be performed ideally 1 week after the first challenge to ensure there is no delayed onset reaction.

We have needed to do this about 5 times over the past year and have had no positive oral amoxicillin/clavulanic acid 250 mg challenge reactions to date. "

Patricia McNally, MD, FAAAAI

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