Warfarin is an anticoagulant indicated for the treatment or prevention of clot formation in cases of deep vein thrombosis, stroke, heart attack or heart valve disease, for example. This medicine works by inhibiting clotting factors dependent on vitamin K, which participates in the production of proteins necessary for blood clotting.
Warfarin can be found in pharmacies or drugstores, in the form of 2.5 mg, 5 mg or 7.5 mg tablets under the trade name Marevan, or as a generic under the name “warfarin sodium”.
This anticoagulant, also popularly known as “blood thinning medicine”, should only be used with medical advice, and with individualized doses, based on the results of blood tests that measure blood clotting factors.
What is it for
Warfarin is indicated for the treatment or prevention of clot formation in the following situations:
Additionally, warfarin may be indicated to prevent clot formation due to the use of mechanical heart valve prostheses.
Warfarin acts by inhibiting clotting factors that depend on vitamin K, and is indicated to prevent the appearance of new clots in blood vessels, without acting on clots that have already formed.
How to drink
The warfarin tablet should be taken with a glass of water, before or after a meal, at the times established by the doctor.
The dosage of warfarin varies according to the results of the blood test in which the prothrombin time and INR are measured, with the normally recommended initial dose being 2.5 mg to 5 mg per day, and the maintenance dose varies from 2.5 mg to 10 mg per day, as per medical advice.
The use of warfarin must be carried out under regular medical supervision, with blood tests being necessary at least once a month, or according to medical indications, such as prothrombin time and INR, in order to adjust the treatment dose.
The duration of treatment with warfarin should always be advised by your doctor.
Care during treatment
Some precautions are important during treatment with warfarin, such as:
- Brush your teeth gently with a soft toothbrush;
- Be careful when shaving or waxing;
- Avoid the consumption of alcoholic beverages;
- Avoid consuming teas or herbal remedies, such as garlic, Ginkgo Biloba or ginseng, without medical advice;
- Avoid using anti-inflammatory medications without medical advice, such as diclofenac, ibuprofen, acetylsalicylic acid or naproxen, as they may increase the risk of bleeding;
- Avoid consuming juices, such as grapefruit juice, cranberry juice or noni juice, as they may increase the risk of side effects.
Furthermore, you should avoid making changes to your diet without the guidance of your doctor or nutritionist, as foods rich in vitamin K can reduce the effectiveness of warfarin, such as liver, green leafy vegetables or vegetable oils, for example. Check out the list of foods rich in vitamin K that should be avoided.
Possible side effects
The most common side effects that may occur during treatment with warfarin are bleeding or hemorrhages, which can appear anywhere in the body, and which must be reported immediately to the doctor responsible for the treatment.
The main symptoms of bleeding or hemorrhages are bruises, purple spots on the body with no apparent cause, bleeding from the nose or gums, blood in the urine, dark stools that look like coffee grounds, coughing or vomiting with blood, heavy menstruation, abnormal vaginal bleeding, or difficulty stopping blood from small cuts or injections.
In addition, you should seek immediate medical attention or the nearest emergency room if symptoms such as sudden and intense headache, weakness, dizziness, swelling of the body or any limb, sudden and intense pain in the leg or feet, fingers, or purplish nails, paleness or cold sweat.
Warfarin can also cause side effects such as anemia, hair loss, fever, nausea, diarrhea, or allergic reactions.
Who shouldn’t use
Warfarin should not be used by pregnant women as it can cause malformations in the fetus’s face or central nervous system and congenital problems in the baby. Furthermore, it can also cause bleeding in the fetus and increase the risk of miscarriage.
This medicine should not be used during breastfeeding, as it is not yet known whether warfarin passes to the baby through breast milk.
Warfarin should also not be used by children or people who have stomach or intestinal ulcers, hemophilia, kidney or liver failure, brain aneurysm, aortic aneurysm, recent surgery on the brain, eyes or spinal cord, cancer of the viscera, deficiency of vitamin K, severe and uncontrolled high blood pressure, or bacterial endocarditis.
Furthermore, warfarin should not be used in people who are allergic to warfarin or any other component of the formula.
