Coumadin is the brand name of a prescription drug, warfarin, used to prevent blood clots from growing larger or forming in your body. Your doctor may prescribe it for irregular heartbeat, a blood clot in your lungs or a vein, or if you've suffered a heart attack. Your doctor may prescribe vitamin B-12 if you are anemic, or you may take a B-12 supplement to boost health through purported benefits that include improving memory, preventing macular degeneration and improving sleep. Though neither is contraindicated for the other, do not combine Coumadin and vitamin B-12 without consulting your doctor.
Significance
Coumadin is a blood-thinning medication classified as an anticoagulant. The drug decreases your blood's ability to clot. Taking Coumadin with certain herbs, vitamins and additional medications will increase your risk for bleeding or bruising. This may cause severe bleeding that can become life threatening. There are other vitamins and herbs that can interfere with Coumadin's anticoagulant action.
Vitamin B-12
Your body needs vitamin B-12 for proper red blood cell formation. You also require the vitamin for DNA synthesis and neurological function. Your body has a limited ability to absorb vitamin B-12 from supplements. A deficiency in vitamin B-12 causes anemia, weakness and fatigue. Numerous drugs can interfere with your body's use, absorption or excretion of vitamin B-12. However Coumadin is not one of them, according to "The Essential Herb-Drug-Vitamin Interaction Guide," by George T. Grossberg and Barry Fox. Drugs that do affect vitamin B-12 in your body include numerous antibiotics such as amikacin, amoxicillin, azithromycin, cefadroxil, dicloxacillin, erythromycin, penicillin and linezolid. Antiviral medicines used to prevent HIV cells from multiplying, such as zidovudine, also affect vitamin B-12 in your body.
Coumadin Vitamin and Herb Contraindications
Vitamin B-12 is not one of the contraindicated vitamins for Coumadin. Vitamins that are contraindicated for Coumadin are vitamins A, C, E and K. Taking this drug along with vitamins A and E can raise your risk for bruising and bleeding. Vitamins C and K may interfere with the action of Coumadin. Herbs and vegetables that contain vitamin K include cabbage, parsley, alfalfa, stinging nettle and watercress. Herbs with anticoagulant action include anise, bogbean, ginger, garlic, ginkgo biloba, red clover, horse chestnut, angelica, turmeric and white willow.
Vitamin B-12 Contraindications
Vitamin B-12 is sometimes given as an injection or as a prescription medication. Anticoagulants such as Coumadin are not contraindicated for B-12 prescriptions. Medicines that suppress gastric acid and gastric intrinsic factor are contraindicated, such as cimetidine, ranitidine, famotidine, nizatidine, omeprazole, lansoprazole, esomeprazole, rabeprazole and pantoprazole.
References
- PubMed Health; Warfarin; September 2008
- "The Essential Herb-Drug-Vitamin Interaction Guide"; George T. Grossberg and Barry Fox; 2007
- Drugs.com: Coumadin Side Effects
- Office of Dietary Supplements: Vitamin B-12
- Drugs.com: Zidovudine
- Memorial Sloan-Kettering Cancer Center: Vitamin B-12
