One of the reasons that your INR needs to be monitored so regularly is that there are many factors that can affect your INR.

These factors include changes in your

• Other medications including prescription medicines, herbal preparations, vitamins, and medicines you buy 'over the counter'.
• Diet
• Health for example, if you become ill
• Alcohol intake or smoking habit
• Level of exercise

Because these things all play a role in controlling your INR, changes in any of these may cause changes in your risk of bleeding or clot formation.

It is important to discuss any changes in the things listed above with your healthcare provider, for example, if you are planning to quit smoking, start a new herbal preparation, or start an exercise program.