I believe it can. When I'm more active my INR has dropped a bit. I would not get discouraged though. Keep up being active and let your doc adjust your dosage. I have had times where my INR will be steady for months and then for no apparent reason it's not. So my dosages have varied over the years.

Thank you I just thought it was weird. Ive had 5 good reading and all of a sudden 1.4. Ill just keep a record of what I eat and exercise Im doing for the week. I have to go back next week.

I've been averaging 7-10 miles a day on my exercise bike and never thought whether or not it affected my INR. Now I will have to make sure that I continue exercising so that my INR stays within range.
Well, that's a good enough incentive to keep up my exercise!

I don't think exercise is something to be too worried about tracking. When I say a change to my INR from exercise, I'm talking about a big change in the amount of exercise not just going for an hour walk vs a half hour walk. I actually think it's the getting back to normal during recovery that has the biggest affect. To go from maybe being in the hospital, maybe not eating that much and kind of laying around for a while to going back to work or running errands, doing more house work, that increase in activity could make your INR change.

Warfarin is a weird drug and it's not unusual for INRs to change. That's why we have to monitor our INRs regularly.

My 2 cents: So many things can mess with your INR, from over the counter meds, to viruses, to whatever. So I think over analyzing everything we do because we're worried about our INRs changing leads to a very nerve wracking, OCD-like existence with very little positive results.

Yes it can. The more active I became after my first clot, the more I struggled to hit 2, then when winter came, and i backed off a bit on the exercise, and my INR went over 3. I was confused initially, as I was being very consistent, but the pharmacist explained that activity variable can effect INR.

Exercise can definitely affect INR. When I was testing with Warfarin, they could never get my INR stabilized - the reason why they switched to Eliquis).

I began on Warfarin still healing from a broken ankle. My activity level steadily continued to increase keeping my INR was so all over the place. My nurse kept asking is my diet changed and of course it did not. Only thing changing was my activity level. She said not to stop being active and she would modify dosing to accommodate my activity level. For me, my INR never stabilized after a couple months trying so out of concern my doctor switched me to Eliquis.

I am sure it will restabilize. The most important thing is to stay active and let them modify around your activity level.

Yes, excercise does apparently lower INR, but is is not clear why. However, it seems that bleeding risks are reduced as well with physical activity which seems bit of surprise....

http://www.ncbi.nlm.nih.gov/pubmed/25032265

I had been in range for months when about 11 weeks ago I really stepped up my exercising and I reduced my calorie intake... about 3 weeks ago after dropping 25lbs my INR tested at 3.6. I ended up having to skim a mg per day out of my usual dosage. I tested twice since and am back in range but I have one more test (2 week interval) before I feel confident about staying at this new dosage (now at 30 lbs off and counting).

@crash In my opinion the reason your INR increased, requiring a dose change, wasn't specifically from increasing exercise. It makes more sense that it was caused by the decrease in your caloric intake and losing weight. I had the same thing happen in the summer when my mom was dying. My INR had been very stable for years but went up over 4. I wasn't eating or sleeping and I lost 12 pounds the first week and my activity level was increased much more than normal. It was caused from my diet change and weight loss. I didn't need a dose change (just a skipped dose) because I eventually got back on track with my diet.

It seems that not eating anything for a while can increase the INR. Here is a study that shows that fasting can increase the INR.
http://www.ncbi.nlm.nih.gov/pubmed/24354801

However Im not sure if simply eating bit less every day would have increased the INR that much. Naturally if you would have reduced your calorie intake by eating lots of vegetables, your INR should have gone down. I would recommend weekly INR checks if such large alterations in diet or calorie intake is undertaken.

I can personally say that cutting calorie intake can drastically affect your INR. There's K in a lot of different foods... even things that aren't green vegetables... that you don't even realize are there.

I mean, I personally don't eat a huge amount of greens. None, if I'm honest, most days. But, last January I got the flu. I barely ate anything for about five days. And my INR went to 8.

In the ER (and talking to my doctor), everyone agreed that the lack of food had done it. So, I'm more cautious now. If I get sick and my calorie intake drastically changes, I know I'd better be checking my INR often. Don't be fooled into thinking that only green veggies affect your INR. Calories, activity levels, supplements can all have an effect. If you make any lifestyle changes, keeping an eye on the numbers for a few weeks is ALWAYS a good idea.