Cephalosporins are a group of broad spectrum antibiotics developed from the mold Cephalosporium. Cephalosporins are divided into three groups: Cephalosporin N, C and P. Cephalosporin N and C are related to penicillin, while cephalosporin P is a steroid antibiotic similar to fusidic acid.
Cephalosporins work by inhibiting synthesis of the bacterial cell wall, causing cell death. They are particularly effective on rapidly growing organisms. Common side effects include mild upset stomach, nausea, vomiting and diarrhea. More serious side effects that may require medical attention include black, tarry stools, painful or difficult urination and antibiotic-induced colitis. Since cephalosporins are related to penicillin, individuals with a penicillin allergy may also be allergic to cephalosporins.