I've posted before on the long term side effects of coumadin.  This study is a specific example.  After a chronic blood clot was identified in my leg my pcp prescribed coumadin.  After being on coumadin for about 18 months, it became clear to me that my pcp intended the coumadin to be a permanent therapy.

Though my pcp strongly disagreed, I took myself off coumadin and began supplementing with broad spectrum enzymes, nattokinase, vit e and fish oil- all of which have blood thinning effects in addition to a host of beneficial properties.  David