Question: If you were allergic to Penicillin as a child, can you outgrow it?
Answer: Yes, children usually do outgrow it. It’s important to note, however, that most children who are thought to have the allergy by their parents actually do not (when tested by an allergist). An even higher percentage – perhaps 80 to 90 percent – of adults who think they are allergic to Penicillin are incorrect. As a result, instead of tried and true Penicillin, they usually end up with a broad-spectrum antibiotic that’s not only more expensive but may have more side effects and be less effective. If you think you are allergic to Penicillin, you can be tested by an allergist to confirm it.
Excerpt from: University of California, Berkeley Wellness Letter Special Spring/Summer Issues 2014.