Treatment for bleeding associated with warfarin depends upon the level of bleeding, the INR elevation, and risk factors for forming a blood clot. There are several methods to reverse bleeding from warfarin, including administering vitamin K, prothrombin complex concentrate (PCC), and fresh frozen plasma (FFP).

• Bleeding events with warfarin can be reversed by the use of the made-made form of vitamin K₁, also called phytonadione. Due to its blood clotting action, vitamin K has the potential to reverse the effects of blood thinning medications (anticoagulants) like warfarin.
• Do not take phytonadione (vitamin K) or warfarin unless told to do so by your doctor.
• Agents to replace vitamin K-dependent clotting factors might be used in serious or life-threatening bleeding.

Depending upon the level of bleeding, INR level, and risk factors for serious outcomes, options your doctor may employ to help reverse bleeding include:

• holding your warfarin dose
• holding warfarin and giving oral vitamin K
• holding your warfarin dose, giving intravenous vitamin K and using fresh frozen plasma (FFP), prothrombin complex concentrate (PCC) or other agents to replace vitamin K-dependent clotting factors (factors II, VII, IX, X).

An INR is a blood test that evaluates your body's response to warfarin. If your INR is elevated but you are not bleeding, your doctor may decide to just hold or reduce your dose of warfarin. In some cases, no vitamin K will be needed.

What is an INR?

Your doctor will regularly monitor your warfarin with a simple blood test called an International normalized ratio, or INR.

• Just like having too much warfarin increases the risk of bleeding, having too little warfarin puts you at risk of forming a blood clot.
• Therefore, the effect of warfarin must be monitored carefully with blood testing. INR tests can help your doctor decide on the best dose of warfarin for you.
• Low INR levels may mean you are at risk for a blood clot that could be harmful. High INR levels put you at risk for dangerous bleeding.

What are the symptoms if I take too much warfarin?

Bleeding is the most common side effect of warfarin.

An overdose of this medicine can cause excessive bleeding, which may be life-threatening or fatal. Symptoms of too much warfarin may include:

• bloody or red, or tarry (black-colored) bowel movements (stool)
• spitting up or coughing up blood
• heavy or abnormal bleeding with your menstrual period
• pink, red, or dark brown urine
• coughing up or vomiting material that looks like coffee grounds
• small, flat, round red spots under the skin
• unusual bruising or bleeding
• continued oozing or bleeding from minor cuts
• sudden headache
• feeling very weak or dizzy
• bleeding gums
• nosebleeds

Seek emergency help or call 911 right away if you have any symptoms or bleeding that will not stop.

Other serious side effects of excessive warfarin include: pain, swelling, hot or cold feeling, skin changes, or discoloration anywhere on your body or sudden and severe leg or foot pain, foot ulcer, purple toes or fingers.

This is not a complete list of symptoms or side effects and others may occur. Ask your doctor for medical advice about side effects.

What increases my risk for bleeding?

In addition to excessive warfarin doses, risk factors for increased bleeding can include liver or kidney disease, certain heart problems, older age, previous history of bleeding, and many different drug interactions, including use of nonsteroidal anti-inflammatory drugs (NSAIDs), including aspirin, ibuprofen (Motrin, Advil), naproxen (Aleve) celecoxib (Celebrex) or diclofenac.

Your doctor will also review your use of other medications and make changes if needed. Warfarin is well-known for many food and drug interactions, some which may be serious.

Be sure to tell your healthcare providers about all the medications you take, including prescription, over-the-counter (OTC), vitamins, and herbal or dietary supplements. Tell them when you start a new medicine, change a dose or stop taking a medicine.

Ask your doctor if it is safe to drink alcohol while you are taking warfarin. Using warfarin together with alcohol can change how your blood clots.

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Don’t we have vitamin K naturally in our bodies?

Yes, natural vitamin K is a fat-soluble vitamin found in our bodies that aids in protein synthesis for blood clotting and in bone formation. It is found throughout the body in various organs such as the brain, bone, heart, liver, and pancreas. Blood-clotting factors that help you stop bleeding are formed in your liver from vitamin K.

Warfarin works by decreasing the ability of your blood to clot by blocking the actions of vitamin K. The man-made form of vitamin K, phytonadione, comes as a prescription medicine taken as an oral tablet or used by injection.

In addition to treating certain bleeding or blood-clotting problems due to medicines or disease, it is used to treat low levels of vitamin K (a vitamin K deficiency).

Why is warfarin prescribed?

Warfarin (brand name: Jantoven) is an oral anticoagulant (“blood thinner”) taken by mouth and a vitamin K antagonist. It interferes with your normal blood clotting process by interfering with an enzyme needed to activate vitamin K in your body.

Warfarin is used to treat or prevent blood clots in your blood vessels, which can reduce the risk of stroke, heart attack, or other serious problems. It may be used in people with irregular heartbeats, people with a heart valve, or in people who have had a heart attack.

Excessive doses, certain drug interactions with warfarin, or unplanned surgery may increase the risk of bleeding if you take warfarin.

Warfarin is often called a “blood thinner” but does not actually make your blood more “thin”. It inhibits a series of clotting factors to keep your blood from clotting to stop a bleed.

• When you cut yourself, there is a series of vitamin K-dependent clotting factors found in your blood that help to form a blood clot to stop the bleeding.
• Warfarin actually blocks (inhibits) these clotting factors and other proteins to keep the blood anticoagulated, but it does not actually "thin" your blood.

Warfarin and vitamin K from food

If you take an anticoagulant medication such as warfarin, your doctor may suggest you eat a consistent amount of vitamin K from food and supplements to help prevent vitamin K from counteracting the effect of your warfarin dose.

Small changes in vitamin K do not usually affect the blood-thinning activity of warfarin, but a large or abrupt change in your diet may interfere with warfarin’s effectiveness.

• Some foods can make warfarin less effective. Eat consistent amounts of food that contain vitamin K on a regular basis.
• Do not change your normal intake of foods such as green leafy vegetables (kale, spinach, brussel sprouts), green tea leaves, liver, broccoli, and cauliflower without checking with your healthcare provider first.
• Ask your doctor or pharmacist for a more complete list of the foods that contain vitamin K.

Talk to your doctor before you make any changes in your diet. Let your doctor and pharmacist know if you eat grapefruit or drink grapefruit, cranberry, pomegranate or Noni juice.

Learn more: Is your blood really thinner with warfarin?

This is not all the information you need to know about warfarin for safe and effective use and does not take the place of your doctor’s directions. Only take warfarin as directed by your doctor or other healthcare provider. Review the full product information and discuss this information and any questions you have with your doctor or other health care provider.

References

• Witt DM, Nieuwlaat R, Clark NP, et al. American Society of Hematology 2018 guidelines for management of venous thromboembolism: Optimal management of anticoagulation therapy. Blood Adv 2018; 2:3257.
• Holbrook A, Schulman S, Witt DM, et al. Evidence-based management of anticoagulant therapy: Antithrombotic Therapy and Prevention of Thrombosis, 9th ed: American College of Chest Physicians Evidence-Based Clinical Practice Guidelines. Chest 2012; 141:e152S.
• Phytonadione. Monograph. Drugs.com. Accessed June 26, 2023 at https://www.drugs.com/mtm/phytonadione-oral-injection.html
• Hull R (author). Management of warfarin-associated bleeding or supratherapeutic INR. Up to Date. Updated Jan. 2023. Accessed June 26, 2023 at https://www.uptodate.com/contents/management-of-warfarin-associated-bleeding-or-supratherapeutic-inr
• Warfarin. MedLine Plus. National Library of Medicine. National Institute of Health (NIH). Accessed June 26, 2023 at https://medlineplus.gov/druginfo/meds/a682277.html
• Warfarin. Monograph. Drugs.com. Accessed June 26, 2023 at https://www.drugs.com/warfarin.html
• Patel S, Singh R, Preuss C, et al. Warfarin. StatPearls. Accessed June 26, 2023 at https://www.ncbi.nlm.nih.gov/books/NBK470313/#
• Phytonadione. MedLine Plus. National Library of Medicine. National Institute of Health (NIH). Accessed June 26, 2023 at https://medlineplus.gov/druginfo/meds/a682659.html#

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