Is Cefdinir a Sulfa based drug?

It is not a "sulfa" or "sulpha" drug. This term applies to drugs whose mechanism of action is dependent upon the sulfonamide group. This group consists of a particular arrangement of a sulfur atom double-bonded to two oxygen atoms and a Nitrogen atom. Cefdinir does contain a Thiazole group, but if there are allergies associated with this, it is unrelated to allergies to sulfonamides. Completely unrelated. I hope that this clarifies things for those who are seeking a reliable reference.