All medicines may cause side effects, but many people have no, or minor, side effects.
No common side effects have been reported with Coumadin.
Seek medical attention right away if any of these severe side effects occur:
Severe allergic reactions (rash; hives; itching; difficulty breathing; tightness in the chest; swelling of the mouth, face, lips, or tongue); back, side, muscle, joint, or stomach pain; black, tarry, or bloody stools; blood in the urine (pink or brown urine); bloody or coffee ground-like vomit; chest pain; decreased urination; dizziness; fainting; fever; numbness or tingling; pain, unusual color, or temperature change in any area of the body; pale skin; purple, dark, or painful toes; shortness of breath; skin sores or ulcers; stroke symptoms (eg, confusion, slurred speech, vision problems, one-sided weakness); sudden severe pain in your legs, feet, or toes; trouble swallowing; unexplained swelling; unusual bruising or bleeding (eg, nosebleed, unusual bleeding from gums, increased bleeding from cuts, increased menstrual or vaginal bleeding, coughing up blood, bleeding at the injection site); unusual headache or weakness; unusual pain, swelling, or discomfort; wounds or sores that do not heal properly; yellowing of the skin or eyes.
This is not a complete list of all side effects that may occur. If you have questions about side effects, contact your health care provider.