Anne is a visionary residency-trained, board-certified pharmacy leader with more than 10 years of healthcare experience. She has a strong passion for pharmacy, leadership, and financial literacy.

David Snyder, PharmD, BCPP, is a board-certified clinical pharmacist and psychopharmacology expert at McLean Hospital in Belmont, Massachusetts.

The use of Jantoven may cause major bleeding that can lead to death. It is important to see your healthcare provider and get regular blood testing to monitor the levels at which your blood clots, also known as INR (international normalized ratio). Medications, diet, and other factors can all interfere with your levels.

It is important to take precautions to minimize your risk for bleeding and to report any signs and symptoms of bleeding to your healthcare provider. Seek immediate medical attention if you have any signs of major bleeding problems, such as but not limited to black, tarry, or bloody stools, coughing up or throwing up blood, and cuts that profusely bleed and take a long time to stop.

Jantoven , a brand of warfarin , is an oral tablet that is only available with a prescription. Warfarin is an anticoagulant (blood thinner), which essentially lessens the creation of certain proteins responsible for adding clotting factors to your blood.

A clot that has formed in the blood can travel to different parts of your body, such as your brain, legs, or lungs. Blood clots can potentially result in a stroke, heart attack, and even death. Jantoven prevents and treats blood clots that may be formed in different parts of your body.

Brand Name(s): Jantoven

Therapeutic Classification: Anticoagulant (blood thinner)

Controlled Substance: N/A

Active Ingredient: Warfarin sodium

Jantoven is used to treat blood clots or thin the blood so clots will not form. The Food and Drug Administration (FDA) approved Jantoven to treat or prevent two common types of blood clots:

Jantoven can be used to reduce the risk of blood clots in people with certain heart conditions (e.g., atrial fibrillation, an irregular and often fast heartbeat), mechanical heart valves, and others who may be at risk.

Jantoven is an oral tablet that ranges from 1 to 10 milligram (mg) doses. It is usually taken at the same time daily or as prescribed by your healthcare provider. Your healthcare provider will adjust your dose if needed, depending on how your body responds to warfarin.

Your provider may also change your dose based on your INR (international normalized ratio), which measures the time it takes for your blood to clot.  The normal range for your INR if you take Jantoven is between 2 and 3, although this depends on what you are taking this drug for and other individual factors.

You may take Jantoven either with or without food. It is not recommended to increase the amount of leafy green vegetables you eat while taking Jantoven. These foods contain high levels of vitamin K, which can interrupt how well your body responds to warfarin. Consult with your healthcare provider, pharmacist, or a registered dietitian before making significant changes to your eating habits.

Also, limit alcohol, grapefruit juice, and cranberry juice consumption while using this medication.

You must talk with your healthcare provider first before starting any other medications, including over-the-counter (OTC) medications, vitamins, and herbal supplements, while on Jantoven. Also consult your provider before making any changes to your weight or your diet while on this medication.

Store Jantoven at room temperature (between 68 and 77 degrees Fahrenheit) and protected from light. Jantoven can be taken with you on short trips outside the home in temperatures ranging from 59 to 86 degrees. It is important to keep this medication in a tightly closed container and out of the reach of children and pets.

Healthcare providers may prescribe Jantoven for off-label uses, meaning for conditions not specifically indicated by the FDA.

Jantoven can be used to prevent blood clots in the veins, known as venous thromboembolism (VTE), in people with cancer. It is important to note that people with cancers such as pancreatic, stomach, lung, brain, and many others have a higher risk of getting VTE. Therefore, your healthcare provider may prescribe Jantoven as a preventive therapy.

Jantoven can also be used for individuals that have had strokes caused by blood clots traveling directly to the brain from underlying heart conditions, such as irregular heart rhythms (e.g., atrial fibrillation).

Jantoven should start working roughly within 24 to 72 hours. You should notice improvements around five to seven days after starting this drug.

Side effects associated with Jantoven use include a risk of bleeding in different areas of the body. This can lead to stomach bleeding, easy bruising, or slow-clotting cuts.

This is not a complete list of side effects and others may occur. A healthcare provider can advise you on side effects. If you experience other effects, contact your pharmacist or a medical professional. You may report side effects to the FDA at www.fda.gov/medwatch or 800-FDA-1088.

Common side effects of Jantoven include:

It is important that you contact your healthcare provider as soon as possible if you begin to experience any of the severe side effects listed below. These signs may be indicating that you are taking too much warfarin and you should contact a healthcare provider immediately:

Serious and life-threatening bleeding is a complication of Jantoven use. This can include bleeding into the brain or internal bleeding. The risk of bleeding is greatest in the first few weeks that you start Jantoven and during illness. Be sure to report any falls or accidents, as well as signs of bleeding.

Rarely, Jantoven can cause death of skin tissue (necrosis or gangrene), which can happen if a blood clot forms and blocks the flow of blood to an area of your body. It is important to monitor any new symptoms such as pain, temperature, or color change in any area of the body and call your healthcare provider right away.

Jantoven may cause other side effects. Call your healthcare provider if you have any unusual problems while taking this medication.

If you experience a serious side effect, you or your provider may send a report to the FDA's MedWatch Adverse Event Reporting Program or by phone (800-332-1088).

The dose of this medicine will be different for different patients. Follow your doctor's orders or the directions on the label. The following information includes only the average doses of this medicine. If your dose is different, do not change it unless your doctor tells you to do so.

The amount of medicine that you take depends on the strength of the medicine. Also, the number of doses you take each day, the time allowed between doses, and the length of time you take the medicine depend on the medical problem for which you are using the medicine.

You may need a lower dose if you are at an advanced age (65 years and older) or of Asian heritage. Even though dosing adjustments are not needed if you have kidney or liver issues, your healthcare provider may monitor and adjust the dose appropriately as you may be more likely to experience bleeding.

If you miss your dose of Jantoven, take it as soon as possible on the same day. Do not take more than one dose to make up for a missed dose. In some cases, you may need to stop taking Jantoven temporarily, such as if you are having a planned procedure or surgery, to lower the risk of any bleeding issues.

It is important to talk to your healthcare provider about any planned procedures while taking this drug so they can advise you appropriately.

Taking too much Jantoven can put you at risk for bleeding. It is important to take this medication exactly how your healthcare provider has prescribed it to you.

Call your healthcare provider if you notice:

These are potential signs of warfarin overdose. It is important to report bleeding of any kind, such as a minor nosebleed that continues for more than 20 to 30 minutes and cannot be stopped. Seek help immediately and do not wait for the bleeding to stop as this can be life-threatening and can lead to death.

If you think you or someone else may have overdosed on Jantoven, call a healthcare provider or the Poison Control Center (800-222-1222).

If someone collapses or isn't breathing after taking Jantoven, call 911 immediately.

It is very important that your doctor check your progress at regular visits to make sure this medicine is working properly. Blood tests, such as an INR, are needed to check for proper dosage and unwanted side effects. Be sure to keep all appointments.

Using this medicine while you are pregnant can harm your unborn baby. Use an effective form of birth control to keep from getting pregnant during treatment and for at least 1 month after the last dose. If you think you have become pregnant while using this medicine, tell your doctor right away.

Make sure any doctor or dentist who treats you knows that you are using this medicine. You may need to stop using this medicine several days before having surgery or medical tests.

Check with your doctor immediately if you have diarrhea, fever, or any symptoms of an infection.

This medicine may cause skin necrosis or gangrene. Call your doctor right away if you have pain, a color change, or a temperature change to any area of your body. Call your doctor right away if you have pain in your toes and they look purple or dark in color. These could be signs of a serious medical problem.

Calciphylaxis or calcium uremic arteriolopathy may occur in patients with or without end-stage kidney disease. Tell your doctor right away if you have purplish red, net-like, blotchy spots on the skin.

Warfarin may increase your risk of having kidney problems, including acute kidney injury. Check with your doctor right away if you have blood in the urine, decreased urine output, muscle twitching, nausea, rapid weight gain, seizures, stupor, swelling of the face, ankles, or hands, or unusual tiredness or weakness.

This medicine may increase your chance of bleeding. Check with your doctor right away if you notice any unusual bleeding or bruising, black, tarry stools, blood in the urine or stools, or pinpoint red spots on your skin. Avoid picking your nose. If you need to blow your nose, blow it gently.

Be careful when using a regular toothbrush, dental floss, or toothpick. Your medical doctor, dentist, or nurse may recommend other ways to clean your teeth and gums. Check with your medical doctor before having any dental work done.

Be careful not to cut yourself when you are using sharp objects, such as a safety razor or fingernail or toenail cutters. Avoid contact sports or other situations where bruising or injury could occur.

It is recommended that you carry identification that says you are using warfarin. If you have any questions about what kind of identification to carry, check with your doctor.

Do not take other medicines unless they have been discussed with your doctor. This includes prescription medicines, nonprescription (over-the-counter [OTC]) medicines, and herbal or vitamin supplements.

Jantoven may not be safe to take if you have:

You should also not take Jantoven if you are pregnant or plan to become pregnant, as warfarin may cause death or birth defects in the fetus. You should use contraception (birth control) while taking the medication and for one month after the last dose. However, it is safe to take Jantoven while breastfeeding, as this drug does not excrete into breast milk. 

Jantoven should be used with caution in older adults (age 65 years and older) due to a higher risk of bleeding problems. If you are in this age group, your healthcare provider may start you on a lower dose to maximize safety. You may be more likely to experience bleeding from taking Jantoven if you have kidney problems.

In general, you should always talk to your healthcare provider before taking new medications that consist of over-the-counter medications (OTC), herbal products, or dietary supplements. Many medications can interfere with Jantoven’s ability to work properly.

Some common OTC pain relievers such as Advil or Motrin (ibuprofen) and Aleve or Naprosyn (naproxen) can increase the anticoagulant effects of warfarin or lead to increased bleeding.

Other medications that are not safe while taking Jantoven are ginkgo biloba and coenzyme Q10 (CoQ10). Due to the number of medications that interact with Jantoven, always check with your healthcare provider before starting a new medication or taking a new herbal or OTC product.

Other medication options that are similar to Jantoven in the prevention and treatment of blood clots include:

The above treatments that do not contain warfarin have fewer dietary restrictions and are typically more convenient to take, requiring no routine blood testing. However, dosing adjustments are still considered regarding age, kidney function, and bleeding risk. Talk to your healthcare provider about other treatment options.

Jantoven is used to prevent or treat blood clots.

You should not take some OTC pain relievers including Advil or Motrin (ibuprofen) and Aleve or Naprosyn (naproxen) with Jantoven. Some herbal and dietary supplements such as ginkgo biloba and coenzyme Q10 (CoQ10) can also interact with Jantoven. Talk to your healthcare provider before starting any new medications or supplements.

Jantoven takes around 24 to 72 hours to start working. Improvements begin to show around five to seven days.

Jantoven can cause such side effects as abdominal pain, bloating, changes in taste, feeling cold or having chills, hair loss, and nausea and vomiting. Bleeding risk is also a complication of taking warfarin medications. Notify your healthcare provider if you have signs of minor or excessive bleeding, such as nosebleeds, bleeding gums, or bruising.

It can be difficult in the beginning to adjust to a new diagnosis of a blood clotting issue such as pulmonary embolism or venous thrombosis. You may feel an initial shock or anxiety trying to make sense of your diagnosis and having to adjust your lifestyle while taking Jantoven. However, there are many ways to help prevent further clotting issues and lead to a successful recovery.  

Some useful at-home recovery tips include:

While the road to recovery may seem long and lonely dealing with a new diagnosis, it is important to know that you are not alone. Talk to your healthcare provider for local support groups in your area of people who share the same diagnosis. Other resources such as Clotcare and Stop the Clot are appropriate online resources if you prefer an online support group.

There are many ways to stay healthy, such as by limiting your alcohol, grapefruit juice, and cranberry consumption while taking Jantoven. You can still eat what you would normally eat. However, do not make any new changes to your diet before talking to your healthcare provider. You can also ask your healthcare provider for a prescription for compression stockings, as these can help your legs feel better as well. 

When it comes to physical activity, it is recommended to move around and stay active. However, only do what is comfortable for you and what's approved by your healthcare provider. Discuss with your healthcare provider recommended exercises and the amount that works for you.

Verywell Health's drug information is meant for educational purposes only and is not intended as a replacement for medical advice, diagnosis, or treatment from a healthcare professional. Consult your healthcare provider before taking any new medication(s). IBM Watson Micromedex provides some of the drug content, as indicated on the page.

The author of this article would like to recognize and thank Renee McLawrence and Chong Yol Gacasan Kim for their contributions.

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