Drug	Side effects
Cephalosporins	Pain at injection site, diarrhea, allergic reactions, Clostridium difficile colitis, hypoprothrombinemia, platelet dysfunction, eosinophilia, positive Coombs' test, serum sickness, cholelithiasis (associated with use of ceftriaxone [Rocephin]) and, rarely, hemolytic anemia, interstitial nephritis, hepatic dysfunction, convulsions (associated with renal failure), neutropenia, thrombocytopenia and confusion
Fluoroquinolones	Gastrointestinal intolerance, headache, insomnia, dizziness, allergic reactions, photosensitivity, elevated liver enzymes and, rarely, papilledema, nystagmus, C. difficile colitis, marrow suppression, anaphylaxis and central nervous system stimulation
Penicillins	Rash, serum sickness, positive Coombs' test and, rarely, neutropenia, thrombocytopenia, elevated liver function tests, increased blood urea nitrogen and creatinine levels, headache, confusion and seizures
Macrolide antibiotics	Diarrhea, nausea, abdominal pain, rash, cholestatic hepatitis and, rarely, C. difficile colitis and hemolytic anemia
Tetracyclines	Gastrointestinal intolerance, stained teeth (in children), hepatotoxicity, photosensitivity, pain with injection and, rarely, allergic reactions, visual disturbances, hemolytic anemia and C. difficile colitis