Caring for children on anticoagulants


If your child has a congenital heart condition, they may need to take an anticoagulant as part of their treatment.

What are anticoagulants?

Anticoagulants are drugs that reduce your risk of developing blood clots. There are two types:

  • those given with an injection and act immediately (e.g. heparin)
  • those given orally (by mouth) and take effect after a few days (e.g. warfarin).

Why are they prescribed? 

Injection anticoagulants are often used immediately after surgery (especially heart valve replacement), when there is a high risk of blood clots developing. This is usually followed by oral treatment.

Anticoagulants may also be prescribed for children with conditions such as cardiomyopathy (a disease of the heart muscle) or who have an abnormal heart rhythm.

How long are anticoagulants given for?

This depends on your child’s individual circumstances. Sometimes, anticoagulants are only needed for a short time – until the risk of a blood clot forming has reduced.

If your child has a mechanical heart valve, they’ll need to take anticoagulants permanently. This is to stop a blood clot forming on the valve. If this happens and the clot becomes dislodged, it could travel to other parts of the body and cause a serious complication, such as a stroke, which could be fatal.

How is the treatment monitored?

 The dosage varies according to your child’s circumstances. It can also vary from time to time during a course of treatment for each child.

If the dose is too high, it can cause bleeding or bruising. If it’s too low, your child is at risk of developing a blood clot.

It’s essential your child has regular check-ups so that their anticoagulant dose can be adjusted if necessary.

When your child comes out of hospital they may need to have a blood test every week. Eventually, the tests may be carried out less frequently. It’s very important to attend clinic as advised by the team caring for your child.

What can interfere with anticoagulants?

A wide variety of things including:

  • diet (cranberry juice, changes in intake of green leafy vegetables rich in vitamin K)
  • multivitamins that contain vitamin K
  • general ill health
  • diarrhoea and vomiting
  • other medication such as antibiotics
  • alcohol.

Some drugs interact with warfarin, and can either increase or decrease its effectiveness.

When you take your child’s prescription for other drugs to the pharmacy, tell the pharmacist that your child is taking an anticoagulant.

Always check with your pharmacist before buying over-the-counter medicines for your child. It may help if you can use the same pharmacy each time.

What are the risks associated with anticoagulants?

Any of these symptoms might mean that your child’s dose of anticoagulant is too high:

  • any bleeding that does not stop by itself, such as prolonged bleeding from cuts or nose bleeds that last for more than a few minutes
  • bleeding gums
  • red or dark brown urine
  • red or very dark brown stools
  • for girls: heavier bleeding during periods or other vaginal bleeding.

If you suspect that your child has any of these symptoms, contact your anticoagulant clinic or the casualty department at your local hospital. Try to have your child’s dosage record card and any other current medication with you.

Make sure teachers and other carers know what to do if your child starts to bleed, or has any of the symptoms listed above. They should contact you immediately. If you are not available, and the bleeding does not stop quickly, they should take the child to a hospital.

What about dental treatment or other treatments that could cause bleeding?

It’s important to let your dentist or surgeon know that your child is taking an anticoagulant, as some treatments may cause excessive bleeding. If your dentist or surgeon thinks your child’s dose or type of anticoagulant may need to be changed, make sure you check with the anticoagulant clinic first.

Can my child exercise?

Swimming, tennis and badminton are all low-risk physical activities your child can take part in.

Children on anticoagulants should avoid contact sports such as rugby and karate. Horse riding is potentially dangerous, as there is a risk that your child could be seriously injured if they fall from the horse.

If your child has extensive bruising or a swollen joint following any injury, you should seek medical advice immediately. The same is true if your child appears drowsy after a head injury.

If your child suffers a head injury, such as falling and hitting their head, or experiences a blow to the head, they must seek medical help without delay to rule out internal bleeding which may not be immediately obvious.

Anticoagulants and pregnancy

Anticoagulants can seriously affect an unborn baby as well as the mother. If you have a daughter who takes warfarin, you both need to be aware of these risks. It’s particularly important your daughter tries to avoid having an unplanned pregnancy.

If your daughter wants to have a baby, it’s best she talks it through with her cardiologist first, so the pregnancy can be properly managed and planned for when her heart condition is most stable.