Bleeding and what to do about it
While warfarin has enormous benefits, the downside is that it can make you bleed more than normal.
This is because while you're taking warfarin, your blood will not clot as easily.
Apart from the risk of bleeding, warfarin is a very safe medicine. It's safe to take for a long time, even many years.
Less serious bleeding
It's usual to bleed more easily than normal while you're taking warfarin.
The kind of bleeding you might have includes:
- bleeding for a little longer than usual if you cut yourself
- occasional nosebleeds (that last for less than 10 minutes)
- bleeding from your gums when you brush your teeth
- bruises that happen easily and take longer than usual to fade
This type of bleeding is not dangerous and should stop by itself. If it happens, keep taking warfarin, but tell your doctor if the bleeding bothers you or does not stop.
Things you can do to help yourself:
- Cuts – press on the cut for 10 minutes with a clean cloth.
- Nosebleeds – sit or stand upright (do not lie down), pinch your nose just above your nostrils for 10 to 15 minutes, lean forward and breathe through your mouth, and place an icepack (or a bag of frozen peas wrapped in a tea towel) at the top of your nose.
- Bleeding gums – try using a soft toothbrush and waxed dental floss to clean your teeth.
- Bruises – these are harmless, but can be unsightly. It might help them fade more quickly if you put an ice pack wrapped in a towel over the bruise for 10 minutes at a time several times a day.
What you can do to prevent bleeding
While you're taking warfarin, be careful when you do activities that might cause an injury or a cut or bruising.
It can help to:
- avoid playing contact sports or other activities that can cause an injury, such as football, rugby, hockey and horse riding
- wear gloves when you use sharp objects like scissors, knives and gardening tools
- stop wet shaving or removing hair with wax – use an electric razor or hair-removing cream instead
- take false teeth (dentures) or retainers out for a few hours a day, if you wear them, to give your gums a rest – do not wear dentures or retainers that do not fit properly
- tell your doctor, dentist or nurse that you take warfarin before you have any medical or dental procedures or surgery – this includes vaccinations and routine appointments with the dental hygienist
Other common side effects
These side effects are usually mild. There are things you can do to help cope with them:
A mild rash
If the rash does not go away within a few days, speak to your pharmacist or doctor.
Hair loss
Speak to a pharmacist or your doctor if this is bothering you.
Talk to your doctor or pharmacist if these side effects bother you or do not go away.
Serious side effects
Serious bleeding
Occasionally, you can have serious bleeding from taking warfarin. This is where you bleed suddenly or without a cut or injury, or bleeding will not stop. This can be dangerous and needs urgent medical attention.
An urgent blood test to check your international normalised ratio (INR) should be done when you get treatment for serious bleeding.
Urgent advice: Call 111 for advice now if:
You have:
- any bleeding that's not heavy but will not stop, or stops then starts again
- pink, red or brown pee, or black poo
- bruises for no reason, they're larger than you'd expect or they keep growing in size
- sudden, severe back pain
- increased bleeding from your vagina during a period or bleeding between periods
- bleeding from your vagina after the menopause
Immediate action required: Go to A&E now if:
- you have a nosebleed you cannot stop and that last longer than 10 minutes
- there's blood in your vomit or you're coughing up blood
These are symptoms of serious bleeding. If you have any serious bleeding, stop taking warfarin.
Bleeding in the brain
Very rarely, warfarin can lead to bleeding in the brain.
Immediate action required: Call 999 now if:
you get any of these symptoms:
- a sudden and severe headache
- a seizure or fit
- sudden loss of vision or blurred vision
- numbness or tingling in your arms or legs
- slurred speech
- cannot be woken up (lose consciousness)
- difficulty breathing, breathing faster than usual, or chest pain
- any heavy bleeding where blood is spraying, pouring or enough to make a puddle
You may also feel tired, weak or sick.
Do not drive yourself to A&E.
The person you speak to at 999 will give you advice about what to do.
Serious allergic reaction
In rare cases, warfarin can cause a serious allergic reaction (anaphylaxis).
Immediate action required: Call 999 now if:
- your lips, mouth, throat or tongue suddenly become swollen
- you're breathing very fast or struggling to breathe (you may become very wheezy or feel like you're choking or gasping for air)
- your throat feels tight or you're struggling to swallow
- your skin, tongue or lips turn blue, grey or pale (if you have black or brown skin, this may be easier to see on the palms of your hands or soles of your feet)
- you suddenly become very confused, drowsy or dizzy
- someone faints and cannot be woken up
- a child is limp, floppy or not responding like they normally do (their head may fall to the side, backwards or forwards, or they may find it difficult to lift their head or focus on your face)
You or the person who's unwell may also have a rash that's swollen, raised, itchy, blistered or peeling.
These can be signs of a serious allergic reaction and may need immediate treatment in hospital.
Do not drive yourself to A&E.
The person you speak to at 999 will give you advice about what to do.
Other side effects
These are not all the side effects of warfarin. For a full list, see the leaflet inside your medicine's packet.
Reporting side effects
You can report any suspected side effect using the Yellow Card safety scheme.
Visit the Yellow Card website for more information about reporting side effects.