Anticoagulants are medications that keep your blood from clotting or turning into solid clumps of cells that stick together.

What Is the Most Common Anticoagulant?

The most commonly prescribed anticoagulant is warfarin. Newer types of anticoagulants are also available and are becoming increasingly common.

Most come in pill form. Other, more powerful types of this blood thinner are given as a shot or through an IV, either in the hospital or at home. Some of the more well-known ones are heparin, low molecular weight heparins and fondaparinux.

Some popular ones include:

• Apixaban (Eliquis)
• Rivaroxaban (Xarelto)
• Dabigatran (Pradaxa)
• Edoxaban (Savaysa, Lixiana)
• Fondaparinux (Arixtra)
• Heparin
• Low molecular weight heparins (Fragmin, Innohep, and Lovenox)

When Anticoagulants Are Used?

If a blood clot blocks the flow of blood through a blood vessel, the affected part of the body will become starved of oxygen and will stop working properly.

Depending on where the clot forms, this can lead to serious problems such as:

• strokes or transient ischaemic attacks (“mini-strokes”)
• heart attacks
• deep vein thrombosis (DVT)
• pulmonary embolism

Treatment with anticoagulants may be recommended if your doctor feels you’re at an increased risk of developing one of these problems. This may be because you’ve had blood clots in the past or you’ve been diagnosed with a condition such as atrial fibrillation that can cause blood clots to form.

You may also be prescribed an anticoagulant if you’ve recently had surgery, as the period of rest and inactivity you need during your recovery can increase your risk of developing a blood clot.

What Is the Difference Between Anticoagulants and Blood Thinners?

Blood thinners are medications that prevent blood clots from forming. They also keep existing blood clots from getting larger. Clots in your arteries, veins, and heart can cause heart attacks, strokes, and blockages.

There are two main types of blood thinners.

• Anticoagulants such as heparin or warfarin (also called Coumadin) slow down your body’s process of making clots.
• Antiplatelet medications, such as aspirin, prevent blood cells called platelets from clumping together to form a clot.

Some people call anticoagulants blood thinners. However, the blood is not actually made any thinner – it just does not clot so easily whilst you take an anticoagulant.

How Do Anticoagulants Work?

Anticoagulants interfere with chemicals needed to make clots or clotting factors.

Warfarin, acenocoumarol and phenindione block the effects of vitamin K which is needed to make some clotting factors. Blocking vitamin K prevents blood clots forming easily by increasing the time it takes to make fibrin. It usually takes two or three days for these medications to work fully.

Dabigatran (Pradaxa), apixaban (Eliquis), edoxaban (Savaysa) and rivaroxaban (Xarelto) prevent a blood chemical called thrombin from working, which in turn prevents fibrin from being made from fibrinogen. Dabigatran binds to thrombin. Apixaban and rivaroxaban stop thrombin from being made. All four medications work quickly – within two to four hours.

Direct Oral Anticoagulants (DOACs), such as apixaban, dabigatran, have advantages over warfarin: they don’t require regular blood tests, involve no food restrictions, and have fewer medication interactions. 

What Are the Possible Side-Effects?

There are a number of possible side-effects with anticoagulants, and it is not possible to list all of these here. However, the major side-effect of all anticoagulant medications is bleeding.

People who take warfarin, acenocoumarol and phenindione need to have regular blood tests to measure how quickly the blood clots. See the leaflet that comes with your medication for a full list of possible side-effects and cautions.

These medications sometimes react with other medications that you may take. So, make sure your doctor knows of any other medications that you are taking, including ones that you have bought over the counter rather than been prescribed.

Notice: The above information is an educational aid only. Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.