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.