Can i take cefdinir if i am allergic to penacillin? i have taken ceftin without any problems before?

Most people who are truly allergic with PCN can take cephalosporins, especially you took Ceftin without problem in the past. Yes, you can take Cefdinir.

The risk is generally low for cephalosporins like Cefdinir with a history of penicillin allergy, studies have shown between 0 and 8.1% cross reaction. However if the penicillin allergy is anaphylaxis (shortness of breath, facial swelling, requiring an epipen and hospitalization), a medical professional should go over your history and assess your true risk.