How to Take Coumadin warfarin: Side Effects, Dosage
Learn how to take Coumadin (warfarin) as directed: dosage guidance, common side effects, drug interactions, and monitoring precautions for anticoagulation.
Not medical advice. Speak with a healthcare professional before using any medication.
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Updated Feb, 15
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Information sourced from FDA-approved prescribing information and peer-reviewed medical references.
How to Take Coumadin warfarin
How to Take Coumadin (warfarin)
The following information reflects FDA-approved prescribing information for Coumadin (warfarin). Always follow your prescriber's specific instructions:
- Per FDA-approved prescribing information, take it at the same time every day — most people choose the evening so dose adjustments can be made easily after INR results.
- Per FDA-approved prescribing information, use the exact dose your clinician prescribes. Your ongoing dose is adjusted only by INR testing.
- If tablets need splitting, use a pill cutter so each dose is consistent.
- Per FDA-approved prescribing information, be consistent with vitamin K intake. You do not need to avoid it — keep foods like spinach, kale, and broccoli at a similar weekly amount so your warfarin dose remains stable.
- Per FDA-approved prescribing information, if you miss a dose and remember the same day, take it as soon as you remember. If the next day has already started, skip the missed dose — do not double up.
- Per FDA-approved prescribing information, avoid making dose changes on your own. Any adjustments should follow your INR result and your clinician's direction.
- Per FDA-approved prescribing information, take warfarin with or without food. Choose whichever is easier for you to remember each day.
- Per FDA-approved prescribing information, keep all INR appointments. Warfarin requires regular monitoring to remain within the therapeutic range.
If anything about your dosing becomes confusing, reach out to your clinician or anticoagulation clinic.
Warnings Before Taking Coumadin (warfarin)
BLACK BOX WARNING: Per FDA-approved prescribing information, warfarin can cause major or fatal bleeding. Bleeding is more likely during the initiation of therapy and with a higher intensity of anticoagulation (INR greater than 4.0). Regular monitoring of INR is required. Drugs, dietary changes, and other factors affect INR levels achieved with warfarin. Instruct patients about prevention measures to minimize risk of bleeding and to report signs and symptoms of bleeding.
Per FDA-approved prescribing information, avoid in pregnancy unless specifically directed; warfarin can cause fetal harm including fetal hemorrhage and teratogenic effects.
Per FDA-approved prescribing information, tell your clinician about bleeding disorders or recent surgery.
Per FDA-approved prescribing information, share all medicines and supplements; many drugs, herbals, and foods interact with warfarin and can raise or lower your INR.
Per FDA-approved prescribing information, report liver or kidney disease, alcohol use, or fall risk, as these can affect anticoagulation safety and dosing.
Coumadin warfarin Side Effects
Common
Severe
Bleeding or Easy Bruising
Per FDA-approved prescribing information, the most serious effect of warfarin is bleeding, including fatal bleeding. You may notice bruises forming more easily, bleeding gums, or nosebleeds. This happens because warfarin reduces the blood's ability to clot. Report any unusual bleeding to your prescriber promptly. Signs of serious internal bleeding — such as blood in urine, black or tarry stools, coughing up blood, or severe headache — require emergency medical care.
Per FDA-approved prescribing information. Contact your prescriber if side effects persist or worsen.
Normally lasts for:
12–48 hours
Common
Moderate
Prolonged Bleeding from Cuts
Per FDA-approved prescribing information, even small cuts may take longer to stop bleeding. Contact your prescriber if bleeding from minor wounds is prolonged or cannot be controlled with direct pressure.
Per FDA-approved prescribing information. Contact your prescriber if side effects persist or worsen.
Normally lasts for:
12–48 hours
Common
Mild
Gastrointestinal Upset
Per FDA-approved prescribing information, some people experience stomach discomfort, nausea, or mild abdominal pain with warfarin. Taking warfarin with food may help ease GI discomfort.
Per FDA-approved prescribing information. Contact your prescriber if side effects persist or worsen.
Normally lasts for:
2–6 hours
Uncommon
Mild
Hair Thinning
Per FDA-approved prescribing information, gradual, mild thinning of hair can occur with warfarin use. Contact your prescriber if this is bothersome.
Per FDA-approved prescribing information. Contact your prescriber if side effects persist or worsen.
Normally lasts for:
Several days to a few weeks
Uncommon
Moderate
Skin Discoloration or Bruises Without Injury
Per FDA-approved prescribing information, small purple spots or patches under the skin (purpura) may appear due to warfarin's anticoagulant effect. Report significant or worsening skin changes to your prescriber.
Per FDA-approved prescribing information. Contact your prescriber if side effects persist or worsen.
Normally lasts for:
12–48 hours
Uncommon
Mild
Fatigue or Weakness
Per FDA-approved prescribing information, occasionally people describe feeling more tired than usual during warfarin therapy. Discuss persistent fatigue with your prescriber, as it may warrant evaluation.
Per FDA-approved prescribing information. Contact your prescriber if side effects persist or worsen.
Normally lasts for:
6–24 hours
Contact Us for a Personalized Care Plan
Have questions about compounding? Contact Voshell's Pharmacy — we prepare patient-specific medications pursuant to valid prescriptions from your licensed prescriber.
What If You Forgot to Take Coumadin warfarin
What If You Forgot to Take Coumadin (warfarin)?
Per FDA-approved prescribing information, if you miss a dose, take it as soon as you remember on the same day. If you do not remember until the next day, skip the missed dose.
- Never double up to make up for a missed pill.
- Per FDA-approved prescribing information, if you miss more than one dose or it happens often, contact your care team so they can guide you and decide whether your INR needs checking sooner.
- Continue your usual daily dose at your regular time.
What If You Took Too Much Coumadin warfarin
What If You Took Too Much Coumadin (Warfarin)?
If more than the prescribed amount was taken, contact Poison Control at 1-800-222-1222 right away or contact your prescriber or anticoagulation clinic immediately. For children or if a large amount was ingested, seek urgent medical care immediately.
Per FDA-approved prescribing information, if you notice any unusual bleeding, blood in stool or urine, prolonged bleeding from cuts, or severe bruising, seek urgent medical care.
Do not take additional warfarin until a clinician advises you.
Keep this and all medications out of reach of children.
How Much Does Coumadin warfarin Cost
Cost of Coumadin (warfarin) With Insurance
With many U.S. insurance plans, generic warfarin is typically placed at a low formulary tier. Brand-name Coumadin is used less often and typically carries a higher copay. Prices vary by pharmacy and individual insurance tiers.
Prices vary by pharmacy, dose, location, and insurance plan and may have changed since this page was written. Contact your pharmacy or insurance provider for current pricing.
How Much Does Coumadin warfarin Cost without Insurance
Cost of Coumadin (warfarin) Without Insurance
Prices can vary by pharmacy and tablet strength. Generic warfarin is generally less expensive than brand-name Coumadin, which is rarely stocked. Many people find that large chain pharmacies and discount drug programs offer the lowest prices for the generic version.
Prices vary by pharmacy, dose, location, and insurance plan and may have changed since this page was written. Contact your pharmacy or insurance provider for current pricing.
Resources:
https://www.fda.gov/drugs/postmarket-drug-safety-information-patients-and-providers/warfarin-coumadin
https://medlineplus.gov/druginfo/meds/a682277.html
https://www.mayoclinic.org/drugs-supplements/warfarin-oral-route/description/drg-20070945
https://www.nhs.uk/medicines/warfarin
https://www.uptodate.com/contents/warfarin-beyond-the-basics
