Does Alcohol Affect Warfarin?

Alcohol can have a dramatic impact on how warfarin works in your body. Learn about how warfarin interacts with alcohol and the potential risks involved.

Warfarin is one of the most common medications prescribed in the United States. However, this drug can interact poorly with a variety of different foods and substances. More than two-thirds of American adults consume alcohol each year, so many wonder whether it’s safe to drink while taking warfarin. The following overview explains how warfarin works, its side effects and its interactions with alcohol.

What Is Warfarin?

Warfarin is a prescription anticoagulant (blood thinner) used to prevent blood clots in a wide variety of medical conditions. Some people may take warfarin only briefly, such as after a knee or hip replacement surgery. Others may take the drug for the rest of their lives for conditions like deep vein thrombosis (DVT), which causes recurrent blood clots in extremities, or a heart condition called atrial fibrillation.

Warfarin prevents blood clotting by interfering with the body’s use of vitamin K, a substance that allows blood to clot. Doses of warfarin are highly customized to keep a number called an international normalized ratio (INR) within a certain range. Your goal INR will vary depending on your reasons for taking warfarin and whether you have had any serious bleeding or clotting while on the drug. If your INR is too low, you can be at a higher risk for blood clots; if your INR is too high, you can be at a higher risk for bleeding.

People who take warfarin need to get blood checks on a regular basis for as long as they are on the drug. These checks monitor their INR and ensure they do not have signs of serious side effects, such as bleeding.

Warfarin Food and Drug Interactions

While warfarin is an important drug to prevent life-threatening blood clots, it has a notoriously high number of interactions with drugs and food. For example, people on warfarin are advised to keep a consistent intake of foods that contain vitamin K, such as green, leafy vegetables.

In addition, many antibiotics have drug interactions with warfarin. To prevent food or drug interactions, people on warfarin are instructed to call their doctor if they ever start or stop taking a new prescription or over-the-counter drug. They should also let their doctor know about any changes in diet. Alcohol intake is another substance that people on warfarin should monitor.

Alcohol and Warfarin

Alcohol can have a variable impact on warfarin, depending on whether you are a regular drinker or not:

• If you regularly drink consistent amounts of alcohol: Over time, your alcohol intake can lower your INR. Generally, your doctor can adjust your warfarin dose accordingly to keep your INR in its goal range. However, this also means that if you were to suddenly stop drinking, your INR might unexpectedly increase and put you at a higher risk of bleeding. For this reason, it is important to inform your doctor if you expect any changes in your alcohol intake.
• If you do not regularly drink alcohol: Suddenly consuming alcohol when your body is not used to it can cause your INR to increase, putting you at a higher risk of bleeding. If you expect to drink on a certain occasion, such as at a party or celebration, it is important to let your doctor know so that they can plan to keep a closer eye on your INR afterward.

Can Alcohol Increase Bleeding Risk?

Although drinking can potentially increase bleeding risks in people who use warfarin, alcohol can still increase these risks on its own. This is because of alcohol’s impact on platelets — the cell fragments that help blood clot.

Is It Safe To Drink Alcohol While on Warfarin?

If possible, it is best to avoid drinking alcohol while on warfarin. This is because alcohol can negatively impact your INR as well as increase your risk of bleeding. Regardless, it is important to inform your doctor or anticoagulation clinic before making any changes to your alcohol intake. By doing so, you can ensure your INR will be monitored more closely during that time.

What If I Can’t Stop Drinking Alcohol?

Alcohol has a known drug interaction with warfarin and can impact your INR, putting you at a higher risk of bleeding or blood clots. In those who do not use warfarin, alcohol still reduces the number of platelets your body makes, which can increase your bleeding risk.

If you are on warfarin and are struggling to control your alcohol use, help is available at The Recovery Village. Our alcohol addiction experts can help you quit drinking safely and put you on the road to a healthier, alcohol-free life. Contact us today to learn more about alcohol addiction treatment programs that can work well for your situation.

Editor – Jonathan Strum

Jonathan Strum graduated from the University of Nebraska Omaha with a Bachelor's in Communication in 2017 and has been writing professionally ever since. Read more

Medically Reviewed By – Dr. Jessica Pyhtila, PharmD

Dr. Jessica Pyhtila is a Clinical Pharmacy Specialist based in Baltimore, Maryland with practice sites in inpatient palliative care and outpatient primary care at the Department of Veteran Affairs. Read more