Antibiotics always, always do a number on my INR. My doc and I usually test 3-4 days after starting the med and make slight dose adjustments at that point to keep me in range. It can be really hard, because by the time you get the right dose to go with the antibiotic, you're ready to stop taking it. Blah!

I had chronic sinus problems a few years ago and I was on and off multiple different antibiotics over a year or so to try to deal the chronic infection in my sinuses. That was an absolute disaster to try to manage, since my drugs were changing every few weeks. It was really, really challenging.

At this point, as a warfarin lifer, I just assume that EVERYTHING I take will mess with my INR... regardless of what the doctors or the pharmacist says. If I start something new, I make a point to let my doc know and to get tested 3-4 days after starting it. I mean, if it doesn't affect my INR, then hallelujah! If it does, though, I'm prepared to deal with it.

I don't remember if you're a long-term warfarin user, but if so, you might want to keep notes about how the antibiotic affected your INR and how much. Then, next time you take it, you can be informed about what to expect and have a plan to address the change.

Hopefully your doc suggested a temporary dose change to deal with the antibiotic effects? And maybe more frequent testing until you get off the med? If not, you might want to push for this to make sure that you're doing OK with the INR until you come off the antibiotic. Best of luck!

Indwen, try to not let that stuff get you down. Warfarin is such a tricky drug. Meds can mess with it, as can food, activity, illness, etc. Your INR is bound to change from time to time, regardless of antibiotic use. I've been on the stuff for 6 1/2 years and there are still times where things just get wonky, sometimes for an obvious reason and sometimes for no apparent reason at all.

I use to get wound really tight about my INR changing and honestly, once I just kind of surrendered to the fact that it's going to change sometimes, that frees you up so you don't feel so enslaved to it all.

Yes, you guys are right about accepting this as a part of the Warfarin train. Actually, my hematologist is suggesting, as long as all the tests come out ok, that I go off the Coumadin in May and begin using baby aspirin. I'm allergic to aspirin. We'll see. Thanks for your thoughts on this subject.

Indwen

LOL MY Antibiotic of choice that drops my INR like a lead brick is the Z-Pak. Heck it works faster and better than an injection of Vitamin K
Hang in there, you'll find over time that a lot of things affect your INR and if you actually tested it daily you would find it probably fluctuates quite a bit. Don't let it get you down but it's a good idea if your going to be on Coumadin for a long time to add that to your allergy list. even though it's not an allergy it's still noteworthy
Hugs Ferr