Truly allergic people, with time, can lose their sensitivity to penicillin.
An infectious agent (such as a virus or bacteria) and not necessarily the antibiotic could have caused the initial reaction.
If amoxicillin is taken when someone is infected with certain viruses, such as infectious mononucleosis, a rash can develop.
Amoxicillin can cause a non-itchy measles-like rash in 7-10% of all people who take it. The majority of people who develop this reaction can take penicillin(s) again without a life-threatening reaction or even a recurrent rash.
In some cases, there is no explanation.
Evaluating For the Penicillin Allergy
After obtaining a thorough history, we will discuss proceeding with skin testing and a drug ingestion challenge, if appropriate.
The entire process will take approximately two to four hours.
The best time to test a child or an adult is when they are well and not in immediate need of this antibiotic.
It may not be practical to test when a patient is sick.
Skin testing has been found to be a safe measure of evaluating for penicillin allergy.
If the penicillin evaluation is negative, it is safe to take penicillin in the future, because the chance of experiencing a reaction is no greater than it would be for a person without a history of penicillin allergy.
