Warfarin

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Warning

Warfarin can cause very serious (possibly fatal) bleeding. This is more likely to occur when you first start taking this medication or if you take too much warfarin.

To decrease your risk for bleeding, your doctor or other health care provider will monitor you closely and check your lab results (INR test) to make sure you are not taking too much warfarin. Keep all medical and lab appointments. Tell your doctor right away if you notice any signs of serious bleeding. See also Side Effects section.

Precautions

Before taking warfarin, tell your doctor or pharmacist if you are allergic to it; or if you have any other allergies. This product may contain inactive ingredients, which can cause allergic reactions or other problems. Talk to your pharmacist for more details.

Before using this medication, tell your doctor or pharmacist your medical history, especially of: blood disorders (such as anemia, hemophilia), bleeding problems (such as bleeding of the stomach/intestines, bleeding in the brain), blood vessel disorders (such as aneurysms), recent major injury/surgery, kidney disease, liver disease, alcohol use, mental/mood disorders (including memory problems), frequent falls/injuries.

It is important that all your doctors and dentists know that you take warfarin. Before having surgery or any medical/dental procedures, tell your doctor or dentist that you are taking this medication and about all the products you use (including prescription drugs, nonprescription drugs, and herbal products).

Avoid getting injections into the muscles. If you must have an injection into a muscle (for example, a flu shot), it should be given in the arm. This way, it will be easier to check for bleeding and/or apply pressure bandages.

This medication may cause stomach bleeding. Daily use of alcohol while using this medicine will increase your risk for stomach bleeding and may also affect how this medication works. Limit alcoholic beverages. Ask your doctor or pharmacist about how much alcohol you may safely drink.

If you have not been eating well, if you have an illness or infection that causes fever, vomiting, or diarrhea for more than 2 days, or if you start using any antibiotic medications, contact your doctor or pharmacist right away because these conditions can affect how warfarin works.

This medication can cause heavy bleeding. To lower the chance of getting cut, bruised, or injured, use great caution with sharp objects like safety razors and nail cutters. Use an electric razor when shaving and a soft toothbrush when brushing your teeth. Avoid activities such as contact sports. If you fall or injure yourself, especially if you hit your head, call your doctor right away. Your doctor may need to check you.

The FDA has stated that generic warfarin products are interchangeable. However, consult your doctor or pharmacist before switching warfarin products. Be careful not to take more than one medication that contains warfarin unless specifically directed by the doctor or health care provider who is monitoring your warfarin treatment.

Older adults may be at greater risk for bleeding while using this drug.

Tell your doctor if you are pregnant or plan to become pregnant. You should not become pregnant while using warfarin. Warfarin may harm an unborn baby. Your doctor should order a pregnancy test before you start this medication. Ask about reliable forms of birth control while using this medication and for at least 1 month after the last dose. If you become pregnant, talk to your doctor right away about the risks and benefits of this medication. If you are planning pregnancy, discuss a plan for managing your condition with your doctor before you become pregnant. Your doctor may switch the type of medication you use during pregnancy.

Since this drug can be absorbed through the skin and lungs and may harm an unborn baby, women who are pregnant or who may become pregnant should not handle this medication or breathe the dust from the tablets.

Very small amounts of this medication may pass into breast milk but is unlikely to harm a nursing infant. Consult your doctor before breast-feeding.

Side Effects

Nausea, loss of appetite, or stomach/abdominal pain may occur. If any of these effects last or get worse, tell your doctor or pharmacist promptly.

Remember that this medication has been prescribed because your doctor has judged that the benefit to you is greater than the risk of side effects. Many people using this medication do not have serious side effects.

This medication can cause serious bleeding if it affects your blood clotting proteins too much (shown by unusually high INR lab results). Even if your doctor stops your medication, this risk of bleeding can continue for up to a week. Tell your doctor right away if you have any signs of serious bleeding, including: nosebleeds that happen often or don't stop, unusual pain/swelling/discomfort, unusual/easy bruising, prolonged bleeding from cuts or gums, unusually heavy/prolonged menstrual flow, pink/dark urine, coughing up blood, vomit that is bloody or looks like coffee grounds, severe headache, dizziness/fainting, unusual tiredness/weakness, bloody/black/tarry stools, chest pain, shortness of breath, difficulty swallowing.

Tell your doctor right away if you have any serious side effects, including: nausea/vomiting that doesn't stop, severe stomach/abdominal pain, yellowing eyes/skin.

This drug rarely has caused very serious (possibly fatal) problems if its effects lead to small blood clots (usually at the beginning of treatment). This can lead to severe skin/tissue damage that may require surgery or amputation if left untreated. Patients with certain blood conditions (protein C or S deficiency) may be at greater risk. Get medical help right away if any of these rare but serious side effects occur: painful/red/purplish patches on the skin (such as on the toe, breast, abdomen), signs of kidney problems (such as change in the amount of urine), vision changes, confusion, trouble speaking, weakness on one side of the body.

A very serious allergic reaction to this drug is rare. However, get medical help right away if you notice any symptoms of a serious allergic reaction, including: rash, itching/swelling (especially of the face/tongue/throat), severe dizziness, trouble breathing.

This is not a complete list of possible side effects. If you notice other effects not listed above, contact your doctor or pharmacist.

In the US -

Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088 or at www.fda.gov/medwatch.

In Canada - Call your doctor for medical advice about side effects. You may report side effects to Health Canada at 1-866-234-2345.

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