Pts are on coumadin for a blood thinning effect, therefore, the side-effect of having low coumadin level or what we typically refer to as
INR is that the blood is not thin enough. Depending
on why he is
on the coumadin (atrial fibrillation, prosthetic valve, DVT, congenital heart disease, etc) he may develop various complications related to clot formation. Coumadin may be difficult to control and adjust.