Omnicef is a reliable antibiotic medication available in 125 mg, 200 mg, and 300 mg strengths. It is part of the cephalosporin class of antibiotics, with cefdinir as its active ingredient. Omnicef is effective in treating a variety of bacterial infections by eliminating the bacteria and inhibiting their regrowth. Produced by reputable pharmaceutical companies, it is marketed under several brand names, including Adcef, Cefdiel, Kefnir, Zefdinir, and Rtist.