Opioids and Warfarin

Publication Date: 
By: Alere Staff

You may be familiar with the names Vicodin®, OxyContin®, codeine, morphine and fentanyl. All of these drugs, whether brand name or generic, are in the class of drugs called opioids. Opioids are pain medications which have been found to be effective for many types of pain and are generally safe when prescribed by a doctor and taken for a short period of time. It is estimated that chronic pain affects more than 100 million people in the United States and about 20-30% of the population worldwide.1 As our population ages, these numbers are expected to increase. 

While opioids can be effective in treating pain, they have many side effects, including mental clouding, nausea, constipation and respiratory depression, a condition which can even lead to death. In addition to these side effects, long term opioid use can lead to physical dependence which makes it difficult to stop taking opioid medications even when the original cause of the pain is gone.1

Opioids and Warfarin

If you are taking warfarin and have been prescribed an opioid, you need to make sure all of your doctors are aware of the medications you are on. Some of these medications contain acetaminophen, which might cause changes in your INR.2 Your doctor may want you to test your INR more frequently while you are on the medication. Don’t forget to take opioids exactly as directed and only for as long as they are prescribed.

Finally, remember that safety is especially important while taking warfarin and opioids if they cause mental clouding. You should never drive a motor vehicle while taking opioids. Other helpful precautions include using handrails when you are getting in and out of the shower or tub and walking up and down stairs; swimming with a buddy; and wearing water shoes while swimming or walking at the beach or pool.


  1. U.S. Department of Health and Human Services. Pathways to Prevention: The Role of Opioids in the Treatment of Chronic Pain. National Institutes of Health. August 16, 2016. Retrieved from the websites: https://prevention.nih.gov/programs-events/pathways-to-prevention/workshops/opioids-chronic-pain.                                         
  2. Hughes GJ., Patel PN., Saxena N. Effect of acetaminophen on international normalized ratio in patients receiving warfarin therapy. Pharmacotherapy. 2011 Jun;31(6):591-7.

Vicodin is the trademark of AbbVie Inc. OxyContin is the trademark of Purdue Pharma L.P. Alere is not affiliated or associated with the noted trademark owners or their related trademarks.