What is an anticoagulant medicine?
are medicines that help prevent blood clots. They are often called blood
thinners, but they do not actually thin the blood. Instead, anticoagulants work
by increasing the time it takes a blood clot to form.
Why is it important to take anticoagulant medicines?
Atrial fibrillation increases your risk of
stroke. People with atrial fibrillation and an
otherwise normal heart are 5 to 6 times more likely to have a stroke than
people who do not have atrial fibrillation.1 People
who have heart valve damage along with atrial fibrillation have an even higher
risk. Taking anticoagulant medicines significantly reduces your risk. The most
commonly used anticoagulants are warfarin and heparin.
What are the risks of taking anticoagulant medicines?
Anticoagulants slow the amount of time it takes for your blood to clot.
This increases your risk of developing problems with bleeding within and around
the brain, bleeding in the stomach and intestines, bruising and bleeding if
injured, and serious skin rash.
You should not take
anticoagulants if you:
- Have unexplained blood in the
- Have uncontrolled high blood pressure.
- Are at
high risk for falling.
- Are unable to take the medicine as
- Drink large amounts of alcohol.
- Are unable or
unwilling to have regular blood tests.
Women with atrial fibrillation who are pregnant or plan
to become pregnant should talk with their doctor about the potential benefits
and risks of taking anticoagulants. These women should not take warfarin (such
as Coumadin) because it can cause birth defects. Use of some anticoagulants,
such as heparin, may complicate pregnancy and childbirth and can increase the
risk of developing
thrombocytopenia if taken over the long term.
How well do anticoagulants work?
significantly reduce the risk of stroke in people who have atrial
fibrillation.2 But how much your risk will be lowered
depends on how high your risk was to start with. Not everyone with atrial
fibrillation has the same risk of stroke. It's a good idea to talk with your
doctor about your risk.
You will want to weigh the benefits of
reducing your risk of stroke with the risks of taking anticoagulants. Warfarin
works well to prevent stroke. But warfarin also increases the risk of bleeding.
Each year about 2 out of 100 people who take warfarin will have a problem with
severe bleeding, and 98 will not.3 But this is an
average risk. Your own risk may be higher or lower than average based on your
What can you do instead of taking anticoagulants?
Aspirin may be a good choice if you are young and have
no other heart or health problems or if you can't take warfarin safely. Aspirin
doesn't work as well as warfarin to reduce your stroke risk. But aspirin is
less likely to cause bleeding problems.
If you are at low risk
for stroke or can't take warfarin, your doctor may recommend that you take
aspirin. Aspirin is an
antiplatelet medicine. It decreases the risk of blood
clotting by preventing the smallest blood cells (platelets) from sticking
together and making a clot.
Aspirin lowers the risk of stroke in
people with atrial fibrillation but not nearly as much as warfarin does. How
much your risk will be reduced depends on how high your risk was to start with.
Aspirin is less likely than anticoagulants to cause bleeding
problems. Bleeding that is bad enough to need treatment in a hospital happens
in 1 or 2 out of 1,000 people who take aspirin.4 This
means that 998 or 999 out of 1,000 people who take aspirin don't have serious
Other antiplatelet medicines, such as clopidogrel
(Plavix), may be used if you can't take aspirin.
For more information, see the topic