Warfarin is an anticoagulant, which means it prevents harmful blood clots from forming. This medication is used to treat or prevent strokes, heart attacks, and deep vein thrombosis (DVT).

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Definition of warfarin dosing

Warfarin is a medication used to prevent or treat harmful blood clots. It works by preventing clotting factors in the blood from joining together, which stops clots from forming or growing larger in your bloodstream and blood vessels.

It is a vitamin K antagonist (VKA). It works by blocking the production of blood clotting factors, leading to an increased risk of bleeding.

  • Warfarin is an anticoagulant that works by reducing the clotting ability of vitamin K.
  • Warfarin reduces the number of clotting factors II, VII, IX, and X in your body, which are necessary for normal blood clotting.

Side effects of warfarin dosing

The medicine may cause you to bleed more easily, including bleeding from minor cuts and wounds. You may also experience bleeding inside your body (bleeding into the stomach, bowels, brain or spinal cord), which can be serious.

You may not know where the blood is coming from because it usually doesn’t have an obvious source of injury. The bleeding may occur without warning and be difficult to stop. Call your doctor or get medical help right away if you experience any of the following signs and symptoms while taking warfarin:

  • Nosebleeds that don’t stop with simple pressure on the bridge of the nose
  • Bruising that takes longer than normal to heal
  • Tarry stools (black bowel movements)

If a blood clot travels to the lungs, it can cause a pulmonary embolism. This is a serious condition that can be fatal.

You may also have bleeding on the inside, which can be serious. It may be difficult for you to tell where the blood is coming from and how bad it is.


Warfarin is a prescription drug used to treat blood clots and prevent them from forming. It is a blood thinner that works by blocking the production of vitamin K, which helps your body form clotting factors.

It was first used in humans in 1954, making it one of the oldest medications still in use today. The drug was initially prescribed as an anticoagulant to reduce the risk of heart attack or stroke caused by atrial fibrillation, but it was later found to be useful for treating other conditions such as deep vein thrombosis (DVT), pulmonary embolism (PE), and venous thromboembolism (VTE).


Why is warfarin called rat poison?

Warfarin is a synthetic derivative of dicoumarol, and since 1948 has had a major role in slaughtering rats and mice by stimulating internal bleeding.

What is the most common side effect of warfarin?

Bleeding is the most common side effect of warfarin.

Can warfarin damage your liver?

Liver injury due to warfarin therapy is rare, but clinically apparent acute liver injury attributable to it has been reported.