Warfarin takes longer to begin working. Both medicines can cause you to bleed more easily. You might notice that, if you cut yourself, the blood takes longer to clot. You might bruise more easily. If you have any unusual or heavy bleeding, call your doctor.
Warfarin has a stronger effect on some people than on others.
This test will tell your doctor how well the warfarin is working. Some other medicines can make warfarin more or less strong. Ask your doctor before you take a new medicine, even nonprescription medicines and vitamins. If you're pregnant, you shouldn't take warfarin. Warfarin can cause birth defects.