Many patients acquire the allergy label as children, when a rash appears after they are treated for an infection with penicillin or closely related drugs. The rash is often blamed on penicillin, while the more likely culprit is the original infection, or a reaction between the infection and the antibiotic. However, genuine penicillin allergies, where our immune systems mistake penicillin for an attacker, do occur rarely and can be very dangerous. So if you think you are allergic but don’t know for sure, your best bet is to visit an allergist. They will complete an evaluation that will confirm whether or not you have the allergy. Even if you do have a penicillin allergy, your immune cells that react to the drug may lose their ability to recognize it. In fact, about 80 percent of people who are allergic to penicillin outgrow their allergy within ten years. This is great news for people who currently identify as allergic to penicillin; the drug may one day save their lives, like others.