Coumadin (Warfarin)
Complete patient guide for uses, dosage, side effects, and safety information
Prescription RequiredQuick Facts
What Is Coumadin Used For?
Coumadin contains warfarin, an anticoagulant medicine that some people call a ‘blood thinner.’ It helps prevent your blood from forming dangerous clots that could lead to serious health problems.
Primary Uses
Coumadin is used to prevent blood from excessive clotting or forming harmful clots. Excessive clotting sometimes occurs when physical mobility is low, and if not treated, it can lead to serious health problems such as strokes or heart attacks.
How It Works
Coumadin works as an anticoagulant to prevent your blood from clotting excessively, reducing the risk of dangerous blood clots forming in your body.
Good to know: This medicine helps control your condition but does not cure it. It’s only available with a doctor’s prescription.
How to Take Coumadin
Follow your doctor’s directions exactly about how much Coumadin to take. Different people require different amounts, and your dosage will be adjusted specifically for you based on blood tests.
Dosage Instructions
Your doctor will determine how much to take through blood tests. Take Coumadin at about the same time each day for the best effect. Swallow the tablets whole with a glass of water – do not crush or chew them. It doesn’t matter if you take it before or after food.
What If You Miss a Dose?
If you miss your dose, take it as soon as you remember on the same day, then take your next dose at the usual time the next day. If you don’t remember until the next day, skip the missed dose and take your next scheduled dose as normal.
Important: Never take a double dose to make up for a missed dose – this may increase your chance of getting unwanted side effects.
Available Tablet Strengths
Side Effects
Like all medications, this medicine can cause side effects. Most are mild and temporary, but some require medical attention.
Common Side Effects
These side effects occur relatively frequently and usually don’t require emergency care:
- bruising
- nosebleeds
- bleeding from gums after brushing
- increased menstrual flow or heavier periods
- purplish and mottled toes
- prolonged bleeding from cuts
- swollen ankles
- painful swelling or discomfort
- stomach pain
- joint pain
- persistent headache or fever
- non-healing wounds or lesions or mottling of skin
Seek immediate medical attention if you experience:
- red or dark brown urine
- symptoms of anticoagulant-related nephropathy (blood in urine, reduced urine output, swelling of legs/ankles/feet, high INR test values, heavy bleeding)
- persistent diarrhea
- red or black bowel motions
- vomiting or coughing up blood
- chest pain
- difficulty breathing or swallowing
- severe skin wounds
- serious fall or injury
Important Warnings
There are important safety considerations before taking Coumadin. Make sure to discuss your medical history and current medications with your doctor.
Who Should Not Take Coumadin
Do not use Coumadin if you are allergic to warfarin or any ingredients, tend to bleed easily, have active ulcers or abnormal blood cells, have moderate to severe high blood pressure, or if the medicine has expired or packaging is damaged.
Medical Conditions to Discuss
Tell your doctor if you have liver or intestinal disease, kidney disease, high blood pressure, protein C deficiency, stomach or duodenal ulcers, bleeding tendencies, fits or convulsions, thyroid problems, heart problems, psychiatric problems, severe diabetes, long-lasting infections, diarrhea, vomiting, fever, alcoholism, or severe allergies.
Pregnancy and Breastfeeding
Do not take Coumadin if you are pregnant as it may affect your developing baby. Do not breastfeed while taking this medicine as the active ingredient passes into breast milk and may affect your baby.
Surgery Alert: If you are going to have surgery, tell the surgeon or anesthetist that you are taking this medicine as it may affect other medicines used during surgery.
Drug Interactions
Many medicines and foods can interfere with Coumadin and affect how it works. Always tell your doctor about all medicines, vitamins, and supplements you’re taking.
Grapefruit interaction: Grapefruit juice may interfere with Coumadin – discuss with your doctor or pharmacist.
- aspirin
- arthritis medications (including glucosamine and chondroitin)
- medications for blood clots, heart attacks or angina
- antihistamines or cough and cold preparations
- some antibiotics
- laxatives
- vitamin C
- vitamin E
- vitamin K
- St John’s Wort
- herbal preparations (garlic, ginseng, feverfew, gingko biloba, ginger)
- alcohol
- cranberry and grapefruit juice
- large amounts of green leafy vegetables
Alcohol & Driving
Coumadin can affect your ability to drive and may interact with alcohol. Take precautions to ensure your safety and the safety of others.
Alcohol
Do not drink alcohol while taking Coumadin. Tell your doctor if you drink alcohol.
Driving and Operating Machinery
Be careful before you drive or use any machines or tools until you know how Coumadin affects you. This medicine may cause dizziness in some people.
Storage
Keep your tablets in the bottle until it’s time to take them – if you remove them, they may not keep well. Store in a cool, dry place where the temperature stays below 30°C, away from light. A locked cupboard at least one-and-a-half meters above the ground is ideal. Keep away from moisture, heat, or sunlight, and out of reach of children.
Overdose Information
If you think you have taken too much Coumadin, seek urgent medical attention immediately. Phone the Poisons Information Centre (Australia: 13 11 26), contact your doctor, or go to the Emergency Department at your nearest hospital, even if you feel fine. Signs of overdose include bleeding, blood in stools or urine, abnormal bruising, or abnormal menstrual bleeding.
Frequently Asked Questions
The source doesn’t specify exact timing, but your doctor will monitor your progress through regular blood tests to determine when the medication is working effectively for you.
Yes, it doesn’t matter if you take Coumadin before or after food. However, try to eat a balanced diet to minimize the possibility of food interfering with the medication.
If you miss your dose, take it as soon as you remember on the same day, then take your next dose at the usual time the next day. If you don’t remember until the next day, skip the missed dose and take your next scheduled dose as normal. Never take a double dose.
No, do not drink alcohol while taking Coumadin. Tell your doctor if you drink alcohol.
No, there are two brands of warfarin called Coumadin and Marevan. Do not swap from one brand to the other.
Remind any doctor, dentist, or pharmacist you visit that you are using Coumadin. If you’re having surgery, tell the surgeon or anesthetist. If you’re having blood tests, tell your doctor as it may interfere with some test results.
Do not stop taking Coumadin or reduce your dose unless your doctor tells you to. This medicine helps control your condition but does not cure it, so stopping suddenly could be dangerous.
Important Disclaimer
This information is intended for general educational purposes only and should not be considered medical advice. Always consult your healthcare provider or pharmacist before starting, stopping, or changing any medication.
If you think you may have a medical emergency, call your doctor or emergency services immediately.