I’ve traveled to China (from Oz) three times over the past 9 months - in fact, I’m here right now, and I notice a significant drop in INR every time.
I put this down to a very different diet to what I would normally eat at home, including a lot more steamed leafy greens. I also tend to drink more (I.e most days) while I’m over here which should have the opposite effect.
Either way, I increase my testing to twice a week, adjust my dosage as required and get on with life. In future trips, I might even consider a prophylactic upping of my dose to preempt the drop.
It typically takes 1-2 weeks for me to stabilise when I get back home.
Dosing the diet has worked well for me so far and I intend to continue doing so.
Alex
The rest of my statement that Pellicle didn't quote was ...unless you load up on kale, so yes, if you significantly increase your intake of leafy greens, it is more likely to affect your INR. I have days where I eat spinach, others where I eat broccoli, others where I each cauliflower and don't see it reflected in my INR.
It may affect how Warfarin is metabolized, but it may not so you can't measure it's effects with the INR. A lot of alcohol will definitely increase your chance of bleeding if you cut yourself because it's an anti-platelet.
As far as a prophylactic dose to preempt the drop, I've never heard of that and wouldn't think it's good science.
When I travel, my INR tends to go up. My diet is similar, my alcohol intake is similar, but I'm usually much more active, so that could explain it. It could also be the gut biome that Pellicle mentioned.
All in all, I've decided that overthinking INR doesn't work for me. I test every two weeks, do nothing if my INR is 2-4, and use the 10% rule if needed. If I'm going to be traveling for more than a couple of days, I test before I leave just so I know what I'm dealing with, but it rarely impacts what I eat, drink, or do.