63 year old female history of rash on face and periorbintal swelling about 5 days after she took 2 grams of amoxicillin po. 1 month later she took 500 mg of amoxicillin and had no rash after 2 days. I saw her for evaluation regarding amoxicillin/penicillin 2 days after she had taken the 500 mg amoxicillin. At this time she said she believed she had right arm pain due to the amoxicillin. Does she need to be tested for penicillin, amoxicillin and challenged with amoxicillin up to 2 gm? Can I assume if she could tolerate 500 mg of amoxicillin she can take 2 grams of amoxicillin without any problem? Do you believe the arm pain is related to amoxicillin? Thanks for your help.


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.

Close-up of pine tree branches in Winter Close-up of pine tree branches in Winter