warfarin and antibiotics
Last reviewed 01/2022
The anticoagulant effect of warfarin and other coumarins is reduced by rifamycins.
Antibiotics that enhance the anticoagulant effect include:
- cephamandole
- chloramphenicol
- ciprofloxacin
- co-trimoxazole
- erythromycin
- metronidazole
- ofloxacin
- sulphonamides
There is possible enhancement of the anticoagulant effect by:
- azithromycin
- aztreonam
- clarithromycin
- nalidixic acid
- neomycin
- tetracyclines
- trimethoprim
There is anecdotal evidence that the INR can be altered following a course of oral broad spectrum antibiotic e.g. ampicillin.