Warfarin helps by thinning the blood but it can be a tricky
drug to take, because it also increases the risk
of brain hemorrhage, so patients must be carefully monitored when taking it.
"Warfarin is linked to the most emergency hospital admissions for adverse drug effects. In one of the first, and largest, studies of its kind, Kaiser Permanente and Massachusetts General Hospital researchers set out the risks and benefits of warfarin".