We have evaluated over 4,000 patients with a history of reactions to penicillin antibiotics. After evaluation and testing, we have found that approximately 90% of these patients can safely take these drugs without fear of a life-threatening reaction.
- We do know that truly allergic people, with time, can lose their sensitivity to penicillin.
- An infectious agent (such as viruses or bacteria) and not necessarily the antibiotic could have caused the initial reaction.
- If amoxicillin is taken when a patient 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.
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 three hours. We feel that 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. We have found that the skin testing is safe, and following a negative skin test, no one has ever suffered a severe life-threatening reaction when given penicillin. We feel that if your penicillin evaluation is negative, it is safe for you to take penicillin in the future, because your chance of experiencing a reaction is no greater than it would be for a person without a history of penicillin allergy.