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Effect of an upset stomach on your meds?

Occasionally I get an upset stomach but surprisingly every time it happens my INR score seems to go upwards for example.

I would have thought the opposite as any Warfarin wouldn't stay in your system long enough for them to work.

Similarly, my blood counts also seem to remain stable as I take HU. I would have thought the FBC levels would jump up with the HU not remaining in the system long enough, but again they don't.

Obviously there is a reason for it - does anyone know why?


4 Replies

Perhaps because the effects are long term - often days or weeks - missing part of one dose maybe not that important in the long term.

I also often wonder why blood pressure taken after venisection is often higher than it was before, even though there is 600ml less blood.


Hi there,

have been on warfarin for almost 10 years and as well as the types of food, INR is also affected by volume of food. I had a very severe stomach infection a few years ago and my INR increased to 10. The docs had really no idea exactly why except that there was no food available to digest with warfarin and hence it 'overdid' its role, as it was the only item in my digestive system. They also hypothesised that I had no vitimin K left from all my vomiting. . .

In the hospital (I was admitted) they gave me vitimin K, which reduced my INR right down to 1 (my target is 2.5 -4) so I wasn't very pleased about that.

Not too sure about your HU issue; but most of it is egested after you take it so it must do its work immediately, hence no increase in FBC conc?



Hi Mark, I passed your query through to Prof Harrison and she has said: I suppose the warfarin level is probably affected by less food, it is much more sensitive to this and has a shorter half life than the HU which is why they are behaving differently in this context I think. I hope this helps Maz


Hi Maz,

Many thanks for asking Prof Harrison.

Always a bit annoying that after weeks of getting INR at a set level it shoots up once in a while. Then away we go again. Tests every few days until it stabilises to a good level.



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