 [ Symptoms ] can i take cefdinir if i am allergic to penicillin [ Disease ] there can be a cross sensitivity people who are allergic to penicillin could also be allergic to cephalosporin antibiotics the class of drug for cefdinir in my experience this rarely happens and i do use cefdinir in penicillin allergic patients unless their history reveals a severe anaphylaxis reaction in the past to penicillin i have also found that many people who think they are allergic to penicillin are really not when they are tested the bottom line your doctor should prescribe it with caution and a warning but in many cases it would be just fine recent studies have found that penicillin allergic patients can take cephalosporin antibiotics safely but there is never a 100 certainty