I have been on Jantovan for over two years and my INR levels have been up and down for the whole time I've been taking it. The same thing happened when I was taking Coumadin . I started taking the Coumadin in 1986 after I had Mitral valve repair done. My INR levels were up and down, anywhere from 1.5 to 5.5 or higher at one point. I just had two valves replaced and one repaired in June and since then I have been checking my INR weekly, but my levels are still going up and down anywhere from 2.4 to 4.9. Could it be the Jantovan that is causing the fluctuation in my INR?