Medicine & USMLE


Anti-Infective Drugs
  1. Vancomycin
  2. Metronidazole
  3. Penicillins
  4. Cephalosporins
  5. Macrolides
  6. Fluoroquinolones
  7. Aminoglycosides
  8. Tetracyclines
  9. Sulfonamides
  10. Rifampin
  11. Isoniazid
  12. Ethambutol
  13. Chloroquine
  14. Acyclovir
  15. Oseltamivir
  16. Azoles
  17. Nystatin
  18. Amphotericin B


Tetracyclines are easy to recognize because they end in “-cycline”, like doxycycline and minocycline. Tetracyclines are a broad spectrum of antibiotics and can treat a wide variety of bacterial infections. Tetracyclines can cause photosensitivity, so patients should be advised to wear sunblock and avoid direct sunlight. Tetracyclines can also cause tooth discoloration in young children. Tetracyclines should not be taken with milk or antacids, as they prevent drug absorption. 

Key Points

  • Tetracyclines
    • Key Drugs
      • -cycline
        • Doxycycline
        • Minocycline
    • Mechanism
      • Broad-spectrum Antibiotic
        • Inhibit bacterial protein synthesis
        • Bacteriostatic
    • Clinical Use
      • Bacterial infections
        • H. pylori
        • Acne
        • M. pneumoniae
        • Urinary tract infection
        • Gingivitis
        • STIs
        • Rickettsia
        • Respiratory infections
    • Side Effects and Adverse Reactions
      • Photosensitivity
        • Teach patient to wear sunscreen and protective clothing when outdoors
      • Tooth Discoloration
        • Occurs if given to children under 8 years old
        • Also can occur in fetus if pregnant woman receives tetracycline therapy in the 3rd trimester
      • Avoid taking with milk and antacids
        • These substances bind with the tetracycline drug and prevent its absorption
      • Teratogenic
        • Impairs bone mineralization in the fetus
      • Do not take with food
        • Doxycycline is the exception and may be taken with food if GI upset occurs
      • Superinfection (C. Difficile, yeast infection, etc.)