I went to lab after 2 months since last test and INR was 7.1. I was afraid and the doc said if any blood issue come to e.r and hold coumadin for 3 days and eat greenies. I did so. after 3 days it was 2.1. Think antibiotics increased it cause used too much for tonsilitis. was 3 terrible days. this is a real problem to use too much antibiotics but necessary to be protected from endocarditis