Jan asked
Hello, my Dr. has prescribed me Omnicef for a sinus infection that is being stubborn and I am allergic to penicillin. I have previously taken cephalexin roughly 10 years ago with no side effects. Should I have any issues taking Omnicef?
Answer
Both Omnicef and Cephalexin are drugs in a class known as cephalosporins. They are NOT considered to be of the penicillin class although there is a SMALL chance of cross reactivity. Current data suggest that the rate of cross-reactivity between penicillins and cephalosporins is probably less than 1%.