Cefixime is an antibiotic used to treat certain infections caused by bacteria. It works by killing the bacteria that cause the infection. Common side effects include nausea, vomiting, or diarrhea. Serious side effects are much less common, but can include a type of diarrhea that is difficult to treat. Notify your healthcare provider right away if you develop watery or bloody diarrhea. Cefixime comes as a tablet, chewable tablet, capsule, and liquid.