Will Missing Coumidin Have Any Ill Effects?

Posted on Sun, 22 Jan 2012

Medically reviewed by Ask A Doctor - 24x7 Medical Review Team

Sun, 22 Jan 2012 Answered on

Sun, 24 Jun 2012 Last reviewed on

Question : If a patient is on 5mg of coumidin and doesn't remember if he took his pill for the day...he's not sure if he lost it or if he took it with his other evening medications. His next INR is for Thursday.

Answered by Dr. James M. Schwartz (8 minutes later)

Hello,

I am happy to answer your question.

Coumidin levels are reflected about 3 days after a dose. So a missed dose would be expected to cause a decrease in the INR and PT about 3 days from now. However, a single missed dose, couched in long term stability, might not change the INR/PT at all. Add to that the fact that the baseline risk of blood clots (which coumidin prevents) is very low - about 6% per year in the case of atrial fibrillation. So if my patient were to tell me this, I would advise them to not worry about it.

I hope this answers your question. Please feel free to follow up with any additional questions.

Best,
Dr. Schwartz

Above answer was peer-reviewed by : Dr. Raju A.T