Comparing dabigatran and warfarin for preventing stroke

If you have atrial fibrillation and you’re already taking warfarin and your INR is stable (in the range INR 2-3), there’s really no need to think about changing. However if you’ve been taking warfarin for a while and your INR is not stable and your warfarin dose changes frequently, or you’ve had other problems with warfarin, then dabigatran might be an option.

Dabigatran (Pradaxa) may not be suitable if you:

  • have a medical condition that increases your risk of bleeding e.g. a blood clotting disorder or a history of bleeding (e.g. in the stomach or brain)
  • have reduced kidney function
  • have liver problems
  • are pregnant, trying to become pregnant, or breastfeeding.

Your doctor can help you decide if dabigatran is a suitable option for you. Find out more about who can take dabigatran and who can’t take dabigatran.

Read the information in the table below if you’re thinking about switching to warfarin from dabigatran.

  Dabigatran Warfarin

How well do they work?

Shown to reduce the risk of stroke in people with atrial fibrillation (AF) in a large clinical trial.

Prevented slightly more strokes than warfarin in people taking a higher dose of dabigatran.

The number of strokes prevented with dabigatran was similar to warfarin.

Known to reduce the risk of stroke in people with atrial fibrillation (AF).

People who do well on warfarin and have stable INR test results are less likely to benefit from switching to dabigatran.

Interactions with medicines and foods

No special diet is required.

Fewer known medicines interactions compared with warfarin

A diet with a consistent intake of vitamin K-rich foods is required.

Many medicines interact with warfarin.

Kidney problems

May not be suitable for people with kidney problems, or taking other medicines that affect their kidneys.

Before starting dabigatran you should have a blood test to check how well your kidneys work.

Can be taken by people with kidney problems.

Side effects

Serious bleeding is the most serious side effect. The rate of major bleeding was similar to warfarin in a large clinical trial. The rate of serious bleeding in the brain was slightly less with dabigatran.

There is no antidote to dabigatran to stop serious bleeding.

Serious bleeding is the most serious side effect, and the rate of major bleeding was similar to dabigatran in a large clinical trial.

Bleeding can be stopped using a vitamin k injection.

Blood tests and monitoring

Yearly blood test to check kidneys

No blood test yet available to check blood clotting

Regular INR blood tests to check blood clotting and if a dose adjustment is needed

Dose adjustment

There are only two doses of dabigatran for AF. You will normally be prescribed one dose only

Dose may need to be adjusted if the INR test shows your blood is clotting too much or not enough.


Dabigatran is a new medicine, so less is known about how to treat bleeding side effects, and its long-term safety.

Warfarin has been used for more than 60 years. Its benefits and side effects are well understood.