Direct Oral Anticoagulants vs Warfarin: Benefits and Side Effects

on September 30, 20248 min read

Direct Oral Blood Thinner vs Warfarin: Benefits and Side Effects

Medically Reviewed By:Gina Jansheski, MD

Before 2010, if you needed a blood-thinning drug to lower your risk of heart attack or stroke, you had only one option – warfarin (Coumadin). While helpful in many cases, this drug comes with some serious disadvantages, such as the need for regular blood tests to monitor its effectiveness.

In 2010, a new type of blood thinners – direct oral anticoagulants – was introduced to the market, but like any drug, these next-generation blood thinners have some side effects of their own.

Read on to learn how you and your doctor can best decide which type of blood thinner is right for you.

What Is Blood Thinner and How Do They Work?

Blood thinners (also called anticoagulants) are drugs that prevent blood from clotting. They also prevent clots from getting stuck in places where they can block blood flow, such as in the small vessels of the legs and in the heart and brain.

They’re commonly prescribed to people with risk factors for developing blood clots, such as:

Atrial fibrillation, a type of irregular rhythm
Venous thromboembolism, a condition in which a clot forms in your veins
A heart valve replacement
A clotting disorder
Previous blood clot, stroke

“Clotting is a very important thing,” says Ronald Wharton, M.D., assistant professor in the department of cardiology at Zucker School of Medicine at Hofstra/Northwell in Hempstead, New York. For example, blood clots form scabs that stop you from bleeding continuously after a small cut. “The problem is, sometimes we have to stop it or reduce the blood’s ability to clot” in order to lessen the risk of stroke (caused by a blood clot in your brain) or pulmonary embolism (a blood clot that makes its way to the lungs), among other issues.

How Does Warfarin Work?

Your blood needs vitamin K to clot. Warfarin interferes with an enzyme that activates vitamin K, and this slows clotting in your body. Because warfarin should not completely stop your blood’s ability to clot, individuals who are prescribed this medication require frequent blood tests to monitor the drug’s effect and have their doses adjusted when needed. Initially, these blood tests will most likely happen every one to two days. Once your doctor has determined your levels are stable, you may only need to be tested once every 12 weeks (although this can vary depending on the patient’s condition).

How Do Direct Oral Anticoagulants Work?

In 2010, a new class of blood thinners, sometimes referred to as non–vitamin K oral anticoagulants (NOACs) or direct oral anticoagulants (DOACs), came onto the market. Like warfarin, they are designed to help prevent strokes and blood clots. Instead of blocking an enzyme that affects vitamin K, DOACs prevent blood clots by blocking either thrombin or factor X, two other enzymes involved in clotting.

However, these drugs aren’t yet approved for all patients who need blood thinners. For example, DOACs are not recommended for people with mechanical heart valves.

One key reason DOACs are attractive to both doctors and patients is that, unlike with warfarin, regular blood monitoring isn’t typically considered to be necessary.

Some common DOAC medications include

Pradaxa (dabigatran etexilate)
Xarelto (rivaroxaban)
Eliquis (apixaban)
Savaysa (edoxaban)
Bevyxxa (betrixaban)

Side Effects of Blood Thinners

Depending on which type you choose, blood thinners can come with different side effects, but all of them have one consequential adverse effect: excessive bleeding.

Excessive Bleeding: A Key Side Effect of All Blood Thinners

Both warfarin and DOACs put you at risk of excessive bleeding. If your blood doesn’t clot, your body can’t make scabs, and you can bleed for longer than usual from a small cut. You’re also at risk of internal bleeding, which is very dangerous and can be fatal (however, antidotes are available to restore the clotting mechanism if needed in an emergency situation).

Watch out for these types of serious bleeding events:

Gastrointestinal bleeding – black or bloody stools, vomiting blood
Intracranial (cerebral) bleeding – headache, vomiting, dizziness, one-sided weakness, seizure, loss of consciousness
Joint bleeding – swelling, pain
Airway bleeding – coughing up blood, difficulty breathing, rapid heart rate

An analysis of 21 trials found that among patients with deep vein thrombosis (a clot that forms in a deep vein in your leg, pelvis or arm), all DOACs caused bleeding less often than warfarin without impacting their effectiveness for preventing clots.

However, it’s important to note that your individual health history is essential when choosing a blood thinner. Recent studies involving people with atrial fibrillation and different comorbid conditions, such as kidney or liver disease, show a varied risk of bleeding with both warfarin and DOACs, so choosing the right blood thinner for you will come down to a conversation between you and your doctor.

Given the overall risk of bleeding with all blood thinners, individuals taking them are generally told to avoid activities that might lead to injuries, such as contact sports. They are advised to call their doctor if they see dark red or black bruises.

Side Effects of Warfarin

Aside from bleeding, some of the more common side effects of warfarin are:

Gas, bloating
Abdominal pain
Bruising
A change in the way things taste

Even though these side effects are more common, it’s important to tell your doctor about them, especially if they become severe or do not subside.

According to the National Institutes of Health, people taking warfarin who experience hives; rash; itching; difficulty breathing or swallowing; swelling of the face, throat, tongue, lips or eyes; swelling of their extremities; fever; diarrhea, loss of appetite or pain in the upper right part of the abdomen should call their doctor immediately, as these reactions could be very serious.

An extremely rare side effect of warfarin is called “purple toes syndrome,” in which painful, purple lesions suddenly appear on the toes and sides of the feet. It most often starts three to eight weeks after beginning warfarin therapy.

Food and Drug Interactions with Warfarin

Warfarin can interact with a variety of medications and supplements, including:

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Some foods can also interfere with the action of warfarin, especially those that are high in vitamin K. Since the drug works by blocking vitamin K, consuming too much of the nutrient can override the drug’s effectiveness.

Because of this serious interaction, it’s recommended that individuals taking warfarin consume about the same amount of vitamin K per day, as any sudden change could change the effectiveness of their anticoagulant.

Some foods that have high amounts of vitamin K include

Kale
Collard greens
Spinach
Romaine lettuce

Side Effects of DOACs

All of the DOACs have similar side effects:

Indigestion
Esophagitis
Upset stomach or stomach pain
Damage to the liver

Food and Drug Interactions with DOACs

Many drugs can interact with DOACs, including

Selective serotonin reuptake inhibitors (SSRIs, a type of antidepressant)
St. John’s wort
Amiodarone (an antiarrhythmic)
Rifampin (an antibiotic used for tuberculosis)
Anticonvulsants
Statins (lovastatin and simvastatin) when taken with the DOAC Pradaxa
Paxlovid

Foods are less likely to interact with DOACs than with warfarin. For example, you do not need to worry about having a consistent intake of vitamin K when taking a DOAC. However, you should ask your physician about any important interactions. Certain DOACs can interact with fatty foods or St. John’s wort.