Thank you for your inquiry.
I would not consider a rash occurring five days after amoxicillin administration or arm pain while taking amoxicillin as manifestations of allergy to amoxicillin. Thus I would not normally test to penicillin or amoxicillin for either one of these manifestations. In addition, if a patient could take 500 mg of amoxicillin without problem, my assumption is that they would normally be able to tolerate a dose of 2 grams as far as a true allergic response is concerned. Of course other adverse reactions, such as gastrointestinal events, might be more common with the higher dose.
Thank you again for your inquiry and we hope this response is helpful to you.
Phil Lieberman, M.D.