Highlights for warfarin
warfarin Side Effects
Side effects that you should report to your doctor or health care professional as soon as possible:
- back pain
- heavy menstrual bleeding or vaginal bleeding
- painful, blue, or purple toes
- painful, prolonged erection
- signs and symptoms of bleeding such as bloody or black, tarry stools; red or dark-brown urine; spitting up blood or brown material that looks like coffee grounds; red spots on the skin; unusual bruising or bleeding from the eye, gums, or nose-skin rash, itching or skin damage
- stomach pain
- unusually weak or tired
- yellowing of skin or eyes
Side effects that usually do not require medical attention (report to your doctor or health care professional if they continue or are bothersome):
- hair loss
warfarin May Interact with Other Medications
Do not take this medicine with any of the following medications:
- agents that prevent or dissolve blood clots
- aspirin or other salicylates
- St. John's Wort
- red yeast rice
This medicine may also interact with the following medications:
- agents that lower cholesterol
- antibiotics or medicines for treating bacterial, fungal or viral infections
- barbiturate medicines for inducing sleep or treating seizures
- certain medicines for diabetes
- certain medicines for heart rhythm problems
- certain medicines for high blood pressure
- chloral hydrate
- female hormones, including contraceptive or birth control pills
- general anesthetics
- herbal or dietary products like garlic, ginkgo, ginseng, green tea, or kava kava
- influenza virus vaccine
- male hormones
- medicines for mental depression or psychosis
- medicines for some types of cancer
- medicines for stomach problems
- NSAIDs, medicines for pain and inflammation, like ibuprofen or naproxen
- quinidine, quinine
- seizure or epilepsy medicine like carbamazepine, phenytoin, and valproic acid
- steroids like cortisone and prednisone
- thyroid medicine
- vitamin c, vitamin e, and vitamin K
How to Use warfarin
Take this medicine by mouth with a glass of water. Follow the directions on the prescription label. You can take this medicine with or without food. Take your medicine at the same time each day. Do not take it more often than directed. Do not stop taking except on your doctor's advice. Stopping this medicine may increase your risk of a blood clot. Be sure to refill your prescription before you run out of medicine.
If your doctor or healthcare professional calls to change your dose, write down the dose and any other instructions. Always read the dose and instructions back to him or her to make sure you understand them. Tell your doctor or healthcare professional what strength of tablets you have on hand. Ask how many tablets you should take to equal your new dose. Write the date on the new instructions and keep them near your medicine. If you are told to stop taking your medicine until your next blood test, call your doctor or healthcare professional if you do not hear anything within 24 hours of the test to find out your new dose or when to restart your prior dose.
A special MedGuide will be given to you by the pharmacist with each prescription and refill. Be sure to read this information carefully each time.
Talk to your pediatrician regarding the use of this medicine in children. Special care may be needed.
They need to know if you have any of these conditions:
- bleeding disorders
- heart disease
- high blood pressure
- history of bleeding in the gastrointestinal tract
- history of stroke or other brain injury or disease
- kidney or liver disease
- protein C deficiency
- protein S deficiency
- psychosis or dementia
- recent injury, recent or planned surgery or procedure
- an unusual or allergic reaction to warfarin, other medicines, foods, dyes, or preservatives
- pregnant or trying to get pregnant
It is important not to miss a dose. If you miss a dose, call your healthcare provider. Take the dose as soon as possible on the same day. If it is almost time for your next dose, take only that dose. Do not take double or extra doses to make up for a missed dose.
Visit your doctor or health care professional for regular checks on your progress. You will need to have a blood test called a PT/INR regularly. The PT/INR blood test is done to make sure you are getting the right dose of this medicine. It is important to not miss your appointment for the blood tests. When you first start taking this medicine, these tests are done often. Once the correct dose is determined and you take your medicine properly, these tests can be done less often.
Notify your doctor or health care professional and seek emergency treatment if you develop breathing problems; changes in vision; chest pain; severe, sudden headache; pain, swelling, warmth in the leg; trouble speaking; sudden numbness or weakness of the face, arm or leg. These can be signs that your condition has gotten worse.
While you are taking this medicine, carry an identification card with your name, the name and dose of medicine(s) being used, and the name and phone number of your doctor or health care professional or person to contact in an emergency.
Do not start taking or stop taking any medicines or over-the-counter medicines except on the advice of your doctor or health care professional.
You should discuss your diet with your doctor or health care professional. Do not make major changes in your diet. Vitamin K can affect how well this medicine works. Many foods contain vitamin K. It is important to eat a consistent amount of foods with vitamin K. Other foods with vitamin K that you should eat in consistent amounts are asparagus, basil, beef or pork liver, black eyed peas, broccoli, brussel sprouts, cabbage, chickpeas, cucumber with peel, green onions, green tea, okra, parsley, peas, thyme, and green leafy vegetables like beet greens, collard greens, endive, kale, mustard greens, spinach, turnip greens, watercress, or certain lettuces like green leaf or romaine.
This medicine can cause birth defects or bleeding in an unborn child. Women of childbearing age should use effective birth control while taking this medicine. If a woman becomes pregnant while taking this medicine, she should discuss the potential risks and her options with her health care professional.
Avoid sports and activities that might cause injury while you are using this medicine. Severe falls or injuries can cause unseen bleeding. Be careful when using sharp tools or knives. Consider using an electric razor. Take special care brushing or flossing your teeth. Report any injuries, bruising, or red spots on the skin to your doctor or health care professional.
If you have an illness that causes vomiting, diarrhea, or fever for more than a few days, contact your doctor. Also check with your doctor if you are unable to eat for several days. These problems can change the effect of this medicine.
Even after you stop taking this medicine, it takes several days before your body recovers its normal ability to clot blood. Ask your doctor or health care professional how long you need to be careful. If you are going to have surgery or dental work, tell your doctor or health care professional that you have been taking this medicine.
Keep out of the reach of children.
Store at room temperature between 15 and 30 degrees C (59 and 86 degrees F). Protect from light. Throw away any unused medicine after the expiration date. Do not flush down the toilet.
Last Updated: July 9, 2014