Ciprofloxacin interaction with sodium warfarin: a potentially dangerous side effect

Am J Emerg Med. 1991 Nov;9(6):551-2. doi: 10.1016/0735-6757(91)90110-6.


Ciprofloxacin, a quinolone antibiotic which exhibits minimal side effects and has broad antimicrobial spectrum, is being used frequently to treat various infections. A patient is reported who had previously maintained a stable prothrombin time on Coumadin for 5 years, and who exhibited a marked prolongation of prothrombin time when placed on ciprofloxacin for gastroenteritis.

Publication types

  • Case Reports

MeSH terms

  • Ciprofloxacin / adverse effects*
  • Drug Interactions
  • Female
  • Humans
  • Middle Aged
  • Partial Thromboplastin Time
  • Prothrombin Time
  • Safety
  • Warfarin / adverse effects*


  • Ciprofloxacin
  • Warfarin