Dr Peter Coleman, Deputy Director of Research at The Stroke Association said:

"Warfarin is a blood-thinning drug that is used to prevent blood clots, one of the main causes of stroke. Warfarin is well-researched, but it can interact with some other medications, like some antibiotics. We are aware that the MHRA has had 12 reports of reactions between Tamiflu and Warfarin and that they are investigating. We recommend that stroke survivors follow the advice on swine flu from the NHS and if they have any doubts to consult their GP."

Source
The Stroke Association