Why take heparin and warfarin together

Heparin and warfarin are both anticoagulants, medications that decrease new development of blood clots, however they work differently.

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What are anticoagulants and why are they used in lupus treatment?
How do anticoagulants work?
How should I take these medications?
Can I take these medications while I am pregnant?
What should I remember while taking anticoagulants?
What are the potential side effects of anticoagulants?
What medications and foods should I avoid while taking anticoagulants?

Heparin is naturally occurring, preventing the formation of clots and the extension of clotting. Meanwhile, warfarin is a vitamin K antagonist that reduces the action of vitamin K to manage clotting. Heparin is used to provide an immediate response while warfarin is generally used for long term treatment. Heparin starts working in your body within 20 to 60 minutes after administration and lasts for 8 to 12 hours. Warfarin is effective 12 to 24 hours after you take it, and peaks at about 1.5 to 4 days, remaining active in your body for 3 to 5 days. For this reason, you will usually be started on heparin and transferred to warfarin within a day or two. You may be kept on both medications until your warfarin dose is therapeutic (INR in range). Heparin is given by injection or IV drip while warfarin is taken orally. Both medications are used to treat:

Deep vein thrombosis (DVT): blood clots in the leg veins
Pulmonary embolism: blood clots in the lungs
Atrial fibrillation: irregular heart beat

The International Normalized Ratio (INR) test is used in managing warfarin dosing. Having a too high an INR means blood clots won’t form quickly enough, which increases your risk of bleeding and bruising. Having too low an INR means the warfarin dose is too low and blood clots could still develop. The Partial Thromboplastin Time, or PTT test, is most often used for people on Heparin instead of INR.

Both Heparin and Warfarin can interact with other medications, supplements or alcohol so it is always wise to have open communication with your healthcare provider regarding your diet and lifestyle. Multiple clinic trials have shown warfarin can help prevent stroke or heart attack. Stay safe by taking your anticoagulant medication exactly as it is prescribed and making sure you follow your doctor’s orders on lab tests and office visits.

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Medically Reviewed by Minesh Khatri, MD on August 09, 2022

Both are anticoagulant medications, or "blood thinners," that help stop your blood from thickening (clotting.) Natural clots help seal wounds on the inside and outside of your body. But unnecessary clots can cause problems. This is especially true when they form inside veins in your leg (deep vein thrombosis) or travel to:

Blood thinners don’t really thin your blood. They just interrupt your body’s natural clotting process. Warfarin and heparin act on different parts of this process.

Warfarin, also known by the brand name Coumadin, is a vitamin K antagonist. That means it works to stop your liver from processing vitamin K into substances, or "factors," that normally help clot your blood.

You get vitamin K from eating green leafy vegetables like broccoli, kale, Brussels sprouts, and spinach. Bacteria in your gut also produce it naturally.

Heparin drugs interfere with certain factors that activate thrombin, an enzyme that helps your blood clot. That means your blood clots less easily.

Warfarin

Doctors usually prescribe warfarin as a daily pill. Your dosage is based on the results of a blood test called a prothrombin time (PT) test. You may also hear this called international normalized ratio (INR) testing, because that ratio is the standard way the test results are reported.

The test tracks how quickly your blood clots. Your doctor will give you this test every few weeks and adjust your dose as needed.

Heparin

Heparin is taken as a shot, and it works more quickly than Warfarin.

You get the type called unfractionated heparin (UFH) through an IV, usually in a hospital. The more you weigh, the more your doctor will give you. The hospital staff will check your blood regularly to make sure your dosage is correct.

You can inject low molecular weight heparin (LMWH) into your skin at home. You might know these drugs as dalteparin (Fragmin) or enoxaparin. As with UFH, your dose is based on your weight. These drugs work in a similar way to UFH. But they're more stable and don't require hospital staff to monitor you.

Pros: Warfarin has a long history of success going back to the 1950s. It’s inexpensive and easy to take in pill form. In case of injury or emergency surgery, doctors can easily reverse its effects with an antidote drug.

Cons: You and your doctor will need to monitor your blood to track the effects of your dose and your diet. Even so, sometimes it's hard to keep just the right amount of warfarin in your bloodstream. You may need to keep track of the vitamin K in your diet to help your doctor estimate the right dose for you. Warfarin may also interact with some prescription and over-the-counter medications and supplements.

Possible Side Effects of Warfarin:

As with all blood thinners, the most serious possible side effect of warfarin is bleeding that won’t stop.

UFH Pros: This kind of heparin works quickly to stop clots, and it wears off rapidly when medical staff stop giving it. You can reverse its effects with an antidote in case of emergency.

UFH Cons: You have to go to the hospital. And medical staff have to watch you closely and test your blood several times a day to make sure you're safe. When you get UFH through an IV for blood clots, you usually need to be in the hospital for 5-10 days.

LMWH Pros: You can inject this kind of heparin into your skin at home. You don't need constant blood testing. It's far more predictable than UFH, and you won't have to change or keep track of what you eat. It’s also safe for pregnant women because it doesn’t pass through to the baby.

LMWH Cons: You have to poke yourself with a needle every day, which can be uncomfortable and scary to some people. This type of heparin can also be expensive. And it’s not as easy to reverse its effects with an antidote as for some other types of anticoagulants.

Potential Side Effects of Heparin:

Swelling, redness, and irritation where you get the shot
Weaker bones
High potassium levels
High liver enzyme levels
Thrombocytopenia, a condition in which your blood has too few platelets. Platelets are cells that help your blood clot.

As with all blood thinners, the most serious possible side effect of heparin is bleeding that won’t stop.

Warfarin (Coumadin)HeparinDalteparin (Fragmin)Danaparoid (Orgaran)Enoxaparin (Lovenox)Tinzaparin (Innohep)

Fondaparinux (Arixtra)

What are anticoagulants and why are they used in lupus treatment?

Warfarin (Coumadin) and heparin are anticoagulants (“blood thinners”), medications that decrease the ability of the blood to clot. About one-third of people with lupus have antibodies to molecules in the body called phospholipids. Sometimes these antiphospholipid antibodies (called anticardiolipin, lupus anticoagulant, or anti-beta2glycoprotein I) can lead to blood clots—thromboses—such as deep venous thrombosis, stroke, or heart attack.

A blood clot by itself is called a thrombus; a blood clot that breaks off and travels elsewhere in your circulatory (blood) system is called an embolus. It is rare for a blood clot to migrate to another part of the body and block one of your blood vessels, but if it does (a condition doctors call a thromboembolism), it is always serious. Blood clots can cut off circulation to your arms, legs, lungs (pulmonary embolism), brain (stroke), and heart (heart attack).

How do anticoagulants work?

Warfarin and heparin work in slightly different ways, but both block the production of certain proteins in your liver that work together to help your blood to clot. These proteins are called “cofactors.” Vitamin K controls the creation of these cofactors in your liver, and warfarin reduces clotting in your blood by preventing vitamin K from working correctly. Heparin also works by preventing certain cofactors, namely thrombin and fibrin, from working correctly. By blocking the process early on, both warfarin and heparin ultimately help to reduce blood clots from forming in your body.

How should I take these medications?

Warfarin comes in tablet form, and heparin must be given as an injection. The amount of medication needed differs with each person and each situation, and individuals on these medications should be closely monitored by their doctors to ensure that they are being given the correct dose.

Can I take these medications while I am pregnant?

Warfarin (Coumadin) is not safe during pregnancy. It can cause birth defects and fetal bleeding. Women who take warfarin must switch to heparin or low molecular weight heparin before they become pregnant, since heparin or low molecular weight heparin (Lovenox, Fragmin) do not cross the placenta into the fetus.

What should I remember while taking anticoagulants?

Do not smoke or drink alcohol while taking anticoagulants. Smoking increases the risk of blood clots and cardiovascular disease, and cardiovascular disease is the number one cause of death in people with lupus. Alcohol can interfere with the effectiveness of anticoagulant medications, can be harmful to your liver, and can irritate your stomach (gastritis), causing bleeding.

Warfarin

Warfarin is the most widely used anticoagulant, but because everyone differs in their physiological make-up, dosage requirements differ from person to person. Blood clotting is a natural protective mechanism employed by the body to seal off damaged blood vessels; any medication that alters this natural protective mechanism must be carefully monitored. People taking warfarin must obtain a blood test every 2-4 weeks to ensure that their blood is thinning to the correct degree without bleeding complications. This test (the INR, discussed below) may be requested several times a week at the beginning of your treatment to ensure that you are started on the correct dose.

The two tests used to monitor warfarin levels in the blood are the Prothrombin Time (or, just “Pro-Time,” or “PT”) and a test called an INR (International Normalized Ratio). In actuality, Prothrombin time is the test used, and INR is simply a standardized way for medical institutions to report consistent values for Prothrombin times. The INR ratio is calculated based on comparison of blood tests against a known standard, and your physician will monitor your warfarin levels based on this INR ratio. Generally, an INR of 2.5 to 3.0 indicates that the patient is receiving the correct dose of warfarin; INR values above 5.0 can be dangerous, and those below 1.0 indicate no warfarin effect.

Heparin

Heparin works faster than warfarin, so it is usually given in situations where an immediate effect is desired. For example, this medication is often given in hospitals to prevent growth of a previously detected blood clot. This medication is also recommended for pregnant women in whom antiphospholipid antibodies have been discovered, since warfarin can be harmful to an unborn child. However, when taken for long periods of time, this medication might increase the risk of osteoporosis. Usually patients switch to warfarin when long term anticoagulant treatment is recommended.

What are the potential side effects of anticoagulants?

The two most serious side effects of anticoagulants are bleeding and gangrene (necrosis) of the skin. Bleeding can occur in any organ or tissue. Bleeding in the kidneys can cause severe back pain and blood in the urine. Bleeding in the stomach can cause weakness, fainting, black stools, or vomiting of blood. Bleeding of the brain can cause severe headache and paralysis, and bleeding of the joints can cause joint pain and swelling.

Other side effects can include rash, bloating, diarrhea, jaundice (yellowing of the eyes and skin), hair loss, itchy feet, pain in the toes, and, in the case of heparin, mild pain, redness, or warmth at the injection site. Bleeding gums, excessive bruising, nosebleeds, heavy menstrual bleeding, and prolonged bleeding from cuts may indicate an overdosing of medication. Notify your doctor if these problems occur.

Some people receiving heparin have experienced a reaction to the infusion, so contact your doctor immediately if you experience any abrupt and serious side effects, such as sudden numbness, confusion, swelling, or trouble breathing.

What medications and foods should I avoid while taking anticoagulants?

While taking anticoagulants, you should avoid supplements with vitamin K. Remember that vitamin K controls the formation of proteins in your liver involved in clotting, so taking in vitamin K can work to counteract your medication and increase your risk of blood clots. In addition, you should avoid medications that can increase your risk of bleeding. These medications include aspirin, NSAIDs, multivitamins with vitamin K, and fish oil. Any antibiotic may change the Coumadin INR test. If you must take an antibiotic, notify your Coumadin clinic so that they may schedule an additional INR check. In addition, be sure to speak with your doctor before starting any new medications. Your physician may also recommend that you carry some sort of identification to alert health professionals of your use of anticoagulants should an emergency or other situation arise.