Warfarin: Uses, Side Effects, Interactions, & Dosing

Warfarin: Uses, Side Effects, Interactions, & Dosing




Warfarin is a blood thinner and an anticoagulant. It helps prevent blood clots and the problems that might occur from them by decreasing their development, and in this article, we talk about this drug in terms of its uses, doses, side effects of its use, and many more.

Warfarin Uses

Warfarin is used to treat patients with blood clots. Such as: leg clot, or pulmonary embolism, and it is also used to prevent the formation of new clots in the body, and preventing the formation of harmful blood clots helps reduce the risk of stroke or heart attack, and conditions that increase a person's risk of blood clots include the following:

  • Atrial fibrillation; A type of tachycardia.
  • Heart valve replacement.
  • The person had a heart attack recently.
  • Performing some surgeries; Ex: hip or knee replacement.

Dosages Of Warfarin

The dosage of this medicine depends on the person's medical condition, and some laboratory tests. Such as: the (INR) test, in addition to the person's response to treatment, for example, the dose to reduce the risk of stroke and heart attack is 5-10 milligrams per day for people 18 years of age and older after relying on the results of the examination, and the doctor will monitor the person very carefully when taking this medicine to determine the appropriate dose, and to get the best results from it, it must be taken regularly, and the medicine label should be read before starting to take it. Warfarin is taken orally with or without food, depending on the doctor’s directions, and it is taken once a day.

Because this drug is absorbed through the skin and lungs and harms an unborn baby; Women who are pregnant or who want to become pregnant should not take it or inhale the particles coming from its pills.

Warfarin Side Effects

Warfarin causes many side effects, some of which are common, and some of which are dangerous, and these effects include the following:

The most common side effects, which are mainly associated with abnormal bleeding caused by warfarin, They include the following:

  • Abnormal bruising; Such as bruises that cannot be explained, or the growth of bruises in size.
  • Nosebleeds, gums;
  • Bleeding from wounds, and is characterized by the need for a long time to stop.
  • Increased amount and duration of menstrual bleeding.
  • Pink or brown pee.
  • Passing red or black stools.
  • Coughing up blood
  • Vomiting blood, or vomiting a liquid that looks like coffee grounds.

Serious side effects, if a person suffers from these serious effects, he should contact a doctor immediately, and if the symptoms pose a threat to his life, urgently call 911, and these effects include the following:

  • Death of skin tissue, this condition occurs when blood clots form that block the flow of blood to a specific area of ​​the body, usually accompanied by pain, and a change in the temperature or color of the affected area.
  • Blue toe syndrome, which causes pain and a dark purple appearance in the toes.

Warfarin Interactions With Other Medicines

Warfarin interacts with other medicines, vitamins, or herbs that a person is taking. The doctor must know all the medications and products that the patient takes, and manage them very carefully.

The most prominent drugs that interact with warfarin include the following:

Anticoagulants, these drugs increase the risk of bleeding if taken with warfarin, and the most prominent of these drugs are: Comes:

  • Factor X inhibitors; Such as: apixaban, edoxaban, and rivaroxaban.
  • Direct thrombin inhibitors; as dabigatran.

Antiplatelet drugs. The risk of bleeding is increased when warfarin is taken with antiplatelet drugs. Such as: clopidogrel, piprasugrel, and ticagrelor.

Non-steroidal anti-inflammatory drugs, the risk of bleeding also increases when warfarin is combined with this group of drugs:

  • Aspirin.
  • Diclofenac and ibuprofen.
  • Indomethacin and naproxen.

Antidepressants. Antidepressants increase the risk of bleeding when taken with warfarin, including the following:

  • Selective serotonin reuptake inhibitors; Such as: citalopram, escitalopram, fluoxetine, fluvoxamine, paresten, and others.
  • Serotonin and norepinephrine reuptake inhibitors; duloxetine and venlafaxine.

Antibiotics and antifungals, some of which change the way warfarin works in the body; Therefore, the doctor needs to monitor the patient carefully when stopping or starting any antibiotic or fungicide.

The most prominent of these drugs are the following:

  • Antibiotics; Such as: macrolides such as azithromycin, clarithromycin, erythromycin, and trimethoprim sulfamethoxazole.
  • antifungals; Such as: fungal azole drugs, such as fluconazole, itraconazole, ketoconazole, and posaconazole. Some herbal products.

Some herbal products increase the effect of warfarin on the blood fluidity. Such as garlic, Ginkgo Biloba, and some other herbal products reduce the effects of warfarin and increase the risk of blood clots. Such as: Coenzyme Q10, St. John's wort, and ginseng.

Drugs that affect the cytochrome P450 enzyme, this enzyme helps the body process drugs, and drugs that activate this enzyme affect how the body deals with warfarin according to the following:

  • Some drugs increase the amount of warfarin in the body, which exposes the person to the risk of bleeding, these include amiodarone, efavirenz, isoniazid, and metronidazole.
  • Some drugs accelerate the action of this enzyme, which reduces the amount of warfarin in the body, and exposes the person to the risk of blood clots, and these drugs include carbamazepine, nevirapine, phenobarbital, and rifampin.

The Risk Of Taking An Overdose Of Warfarin

If a person accidentally takes an extra dose of warfarin, the specialist must contact the doctor immediately, as the person needs to change his next dose of the drug, or take a blood test, but if the person takes more than one dose of the drug, He will be at risk of severe bleeding and will need to go to the emergency immediately, and it is recommended that the medicine package, or the leaflet inside it, be taken to the emergency with the person, in addition to any medicine left with him.

What Happens If The Patient Forgets To Take Warfarin?

If a person forgets to take a dose of warfarin, he must take it as soon as he remembers, and if he does not remember it until the next day, he should contact the doctor to get the appropriate instructions.

Everything mentioned about the medicine was based on its medical leaflet, but this does not replace the need to consult a doctor.