Antibiotic classes — what to watch
Penicillins and cephalosporins : allergy, cross-reactivity, diarrhea.. Fluoroquinolones (ciprofloxacin) : tendon rupture, QT prolongation, confusion in the older adult, many interactions, avoid in pregnancy and childhood when possible.. Aminoglycosides (gentamicin) : nephrotoxicity and ototoxicity, peak and trough levels.. Vancomycin : infusion reaction if given too fast, nephrotoxicity, trough monitoring.. Macrolides : QT prolongation, interactions.. Metronidazole : no alcohol, metallic taste.. All of them : risk of C. difficile, sometimes weeks after the course ends.