How often do I need to have an INR test?

When starting Warfarin it is likely that you will have blood tests on a daily basis. This will continue until your doctor is satisfied that your INR test results are consistently within the Therapeutic Range set for you.

Once you are in a period of stability, and your INR test results have settled within the desired range, the frequency of testing can be reduced. In most cases testing will be cut to once a week initially but, all being well, you should hopefully see this reducing to monthly or 6 weekly after a while.  If at any time your INR becomes unstable your frequency of testing may be increased again until it comes back under control.

There are many factors that can affect the stability of your INR such as illness, or a change in diet. If you have been unwell, or have any other cause for concern, it is always wise to make an appointment to have your INR checked, particularly if your next routine test is not due for a while.