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"What Are The Side Effects of Coumadin?" Asks Elissa

Written By: Adam Pick, Patient Advocate, Author & Website Founder
Page Last Update: June 24, 2025

Elissa was recently diagnosed with severe mitral regurgitation due to mitral valve prolapse.

In an email to me, Elissa writes, "Hi Adam - I'm going through the challenging process of picking a mechanical or tissue valve in case my valve can not be repaired. I know I'll have to use Coumadin for the rest of my life if I go with a mechanical valve. Are there side effects of Coumadin that I should be aware of? If so, what are the common Coumadin side effects? Thanks for everything! Elissa"

Before answering Elissa's question, I would encourage her (and perhaps you) to review a prior blog titled, "What Is Life Like On Coumadin?". In the comments section of that blog, 20+ patients talk about their experiences of using Coumadin on a daily basis.

That said, the common side effects of Coumadin, according to MedicineNet, can be:

nausea
vomiting
loss of appetite
stomach/abdominal bloating or cramps

According to my research, most patients using Coumadin do not have very serious side effects. However, it should be noted that Coumadin can cause bleeding if its effect on your blood clotting proteins is too much (unusually high PT and INR results).

Also, please, please, please remember to tell your doctor immediately if any of these signs of serious bleeding occur:

unusual pain/swelling/discomfort
prolonged bleeding from cuts or gums
persistent nosebleeds
unusually heavy or prolonged menstrual flow
unusual or easy bruising
dark urine
black stools
severe headaches
dizziness

I know that this listing of potential Coumadin side effects may be enough to sway you right to selecting a pig valve or a cow valve. However, remember that many patients do not experience these side effects. Still, I want to make sure Elissa (and you) are aware of the post-operative realities for patients with these types of valve replacements.

Written by Adam Pick - Patient & Website Founder

Adam Pick is a heart valve patient and author of The Patient's Guide To Heart Valve Surgery. In 2006, Adam founded HeartValveSurgery.com to educate and empower patients. This award-winning website has helped over 10 million people fight heart valve disease. Adam has been featured by the American Heart Association and Medical News Today.

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