Vaughn's Summaries logo  Vaughn's Summaries

Medicine Summaries
Human Blood Clotting

Blood INR Range Chart

Using Coumadin
Internat. Normalized Ratio
Prothrombin Time

by Vaughn Aubuchon

Here is a brief simplified chart of human blood INR Range, showing INR levels, and the factors that affect them.


This chart illustrates typical therapeutic INR levels, while using Coumadin (warfarin) therapy. An INR up to 10 is targeted in hyper-therapeutic situations, where any clotting at all absolutely must be avoided.

Blood INR Range Chart

top of page

  Blood INR Ranges

High Risk Group . . . . . . . . =
Intense Therapeutic Range =
Therapeutic INR Range  =
Undefined INR Range         =
Normal Human INR Range =

3.0 - 4.5
2.5 - 3.5
2.0 - 3.0
1.2 - 2.0
0.8 - 1.2

Foods that RAISE INR*
1. Coumadin, a.k.a. warfarin (generic)
2. Alcohol
3. Aspirin

* Listed by greatest effect



Foods that LOWER INR*
1. Vitamin K Foods
    - Kale
    - Spinach
    - Avocado
2. Co-Q10
3. Green Tea

* Listed by greatest effect


Going Out of Range
If your target INR is 2.0-3.0, a reading of 1.8 is far more significant than a reading of 3.2, since you are much closer to coagulation (blood clot risk). Variations on the high end are far greater, and are to be expected. These numbers above INR=3 are actually targets for some "high risk group" therapies.

INR being too high is less concerning than being too low, unless bleeding becomes an issue. Online reports indicate that your INR must get pretty darned high, before most people actually experience bleeding issues.


top of page

  INR Fluctuation

INR fluctuation results in a lot of people making a lot of money. Medical pronouncements are made demanding your compliance. Getting you to "toe-the-line" has you dancing to the tune of the Anti-Coagulation Clinic (ACC).

The Anti-coagulation business is full of conflicting information. What was good one day, became bad the next. We were told that cranberry juice must be avoided at all costs. New testing has shown that cranberry juice has no effect on INR levels.

Some experts say "eat everything in moderation."
Other experts say "avoid certain foods completely."
Lists of "foods to avoid" vary all over the place, depending upon who wrote the list. Regarding the
Vitamin K content of various foods, I subscribe to the official US Government nutrition data from the Department of Agriculture.


My Take
"Your results may vary." No kidding.
Your INR is always going to fluctuate. Trying to pin it down precisely, by adjusting to every fluctuation, is fruitless, costly, and extremely inconveniencing.

But it IS a big moneymaker for Medicine, Inc.
You dance like crazy, they get paid.
When anticoagulation treatment becomes a Golden Calf, I question my allegiance to it. And whether or not I choose to worship it.

Testing over and over every week is unnecessary. Find a dosing level that is close, and test every 2 months. Micromanaging coumadin levels is a medical gimmick, to relieve you of your money.

I eat WHATEVER I want. The medicine adjusts to ME. I don't adjust to it, based upon some poser's misconceptions and whims.


I'm Done - July 21, 2015
When it became necessary for me to go to the ACC EVERY week, due to fluctuating INR numbers, that did it for me.

Why I quit -

The "sacred cow" aspect of warfarin. You must worship the list of banned foods. I'm not big on religion.

The inconvenience of fighting traffic on Soquel Blvd. to get to the hospital. I HATE traffic. I am a hermit. This makes my blood pressure go up. It is the most stressful event of my week.

The chiding that must be endured for my bad behavior, even though I don't KNOW what it is. If you fail the test, you must return EVERY week, to be scolded again.

A lot of accounting which must be done. Statements are unfathomable.

I like a glass of wine every day. The ACC says, "No booze." Screw it. I am having my daily glass of wine.

Now I can have all the avocado, broccoli, chard, COQ-10, green tea, kale, parsley and spinach that I want! AND ANYTHING ELSE!

7. The DOCTOR, who headed the ACC, whose name was on all my ACC documentation, I NEVER met. Once I was in the program, I was simply a source of income for the ACC, just another statistic. He did not know me from Adam, I was just fodder for the medical, money-making machine.

I am now taking 1/4 Aspirin Daily
81 mg
After 1 week, my INR was 1.5, or in the "Undefined Zone".


Update -
It is now June 2020, 59 months later. No, I did not die. Nor do I plan to, anytime soon.
I LOVE my decision. Lots of kale.
NO MORE rat poison for me.

If I should die from this irreverent change of strategy, I will let you know right away.


top of page

 Cannabis Misinformation

Nurse Ratched informed me that marahoocha had a huge effect on INR, and must be completely avoided. This is pure BS, invented by Nurse Ratched. Pubmed* reports that more study is indicated, because there is little evidence that marijuana impacts INR in any significant way. "Conclusion: To our knowledge, there have been NO OTHER reported cases of warfarin-marijuana interaction."

When conservative, dogmatic critics can't find anything bad, they always say, "More study is needed". They have been doing this for decades, and will continue to do it FOREVER, when they cannot confirm their invented, nonexistent side effects.

Many marijuana studies have been conducted over the years. However, when the results do not support long-standing, ignorant dogma, they are belittled and ignored. "More study is needed." BULL. At least, we now know that INR is unaffected by cannabis. Many people continue to believe what they want to believe, regardless of evidence to the contrary. This is "willful ignorance".

* (
dot gov (US Government Website)
National Institute of Health
National Library of Medicine
National Center for Biotechnology Information



Some Perspective

1948 -
Warfarin was introduced as rat poison. It works by causing the lungs to fill with blood, thereby drowning the rodent in its own blood.

1954 - Warfarin was approved for use as a human blood thinner, and marketed as "Coumadin". Ever since, researchers have been trying to agree what constitutes "therapy", versus what constitutes "dangerous bleeding risk". In 2020, they still can't make up their minds.


top of page

   Vaughn's Other
   HUMAN BLOOD Related

* Blood INR Chart

Blood Test Results

Blood Type Summary

Cholesterol Range Chart

Drug Concentration



INR Prothrombin Time

INR Self-monitoring


The author has no medical training. No advice is intended.
Although the author has tried to be as accurate as possible, errors and misstatements are possible. Consult your doctor for personal advice. I could not find an INR Chart diagram like the above. So, I drew this schematic diagram of the blood clotting levels, to help myself understand the workings of coumadin blood thinning therapy. I hope that it helps you. Understanding how prothrombin time works can help you to reduce your risk of stroke.


top of page

Tags: blood INR range chart, coumadin, warfarin

Have A Great Day!
Vaughn Aubuchon Author Bio

Vaughn's Summaries
©2014, 2020 Vaughn Aubuchon
All Rights Reserved
Site Map

This Vaughns Blood INR Range Chart
Summary was last updated on 2020-06-12.