Tamiflu® (Oseltamivir) and Warfarin

Publication Date: 
Sun, 11/01/2015
By: Alere Staff

We are approaching that time of year again when influenza, or flu, becomes prevalent. Symptoms of the flu come on suddenly and can include fever, chills, muscle aches and a runny nose. The flu is worse than a cold and can spread from person to person very quickly through both touch and through the air.1

Did you know there is a medication that can be given to help? Oseltamivir, known as the Tamiflu®medication, is an antiviral prescription that can be used to help lessen the severity of the flu. However, for the drug to be effective, it must be taken within the first one to two days of the start of symptoms. 2

As helpful as the medication can be, if your doctor gives you a Tamiflu® prescription, be ready to have more frequent INR testing. This medication has been shown to increase the INR.3 Carefully monitor yourself for increased bruising or unusual bleeding and be sure to report this immediately to your doctor. Another factor to consider is that when you don’t feel well and aren’t eating like you normally do, this too can affect the INR.

It is important to remember that the best medicine against the flu is prevention. Check with your doctor first and get a flu shot when recommended. As the season progresses, practice good hand washing techniques and avoid exposure to people who are known to have the flu whenever possible. Note that a Tamiflu® prescription should not be seen as a substitute for the flu vaccination.2

Interested in learning more? Check out these related articles:


  1. Tamiflu for Adults. 2015. Retrieved from the website: http://www.health.govt.nz/your-health/conditions-and-treatments/diseases-and-illnesses/influenza.
  2. Ministry of Health – Manatu Hauora. Influenza. March 28, 2014. Retrieved from the website:http://www.tamiflu.com/tamiflu-for-adults;jsessionid=bUrlasY4XParYdgcYf-RYGrf.gxe601a_node1.
  3. Lee SH, Kang HR, Jung JW et al. Effect of Oseltamivir on Bleeding Risk Associated with Warfarin Therapy: A Retrospective Review. Clin Drug Investig. February 1, 2012; 32(2):131-137.

Tamiflu® is a registered trademark of Genentech USA, Inc.