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Allergy or overdose?



I am 39 and currently being treated for an infection after having dental work. I have taken Amoxicillin 250 mg 3 or 4 times a day in the past, most recently 2 months ago after a root canal(as a precaution, and several times as a child. 3 weeks ago I had a crown put on and last week an extraction that required precaution amoxillin again. Somehow the crowned tooth developed an infection and 2 days after the extraction I had to have an emergency root canal on the crown and a drain hole. They doubled my Amoxicillin to 500 mg 4 times a day. First time I have ever taken this amount. On the 2nd day of this treatment I woke up to severe itching and hives. Is this an allergic reaction or is it due to the double dose? Can you develop allergies after so many years?


Based on this history, this is an allergic drug reaction until proven otherwise.  Hopefully you stopped the medication.  If you require an antibiotic in the future, you should use antibiotics from an alternative class other than Penicillin, penicillin derivatives or cephalosporins.  You should see an allergist in the future who can skin test you to penicillin major and minor determinants to determine if you are truly sensitized to penicillin or penicillin derivatives. 

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Response by:

Jonathan   Bernstein, MD Jonathan Bernstein, MD
Associate Professor of Medicine
College of Medicine
University of Cincinnati