Most of the time, blood is taken from a vein, one type of blood vessel. A doctor, nurse or another health professional specially trained to take blood, will insert a thin needle through the skin and into a vein. They will draw up a small amount of blood into a syringe or special container.

Preparing for the blood test

It is important that your child is as comfortable and relaxed as possible. Talk to your child about what will happen during the test, and why it is needed.

Dealing with pain

Your child may feel a sharp scratch from the needle during the blood test. A spray or cream can be put on the skin before to help stop them feeling any pain. This spray or cream is called a local anaesthetic. The cream is put on about 30 – 60 minutes before the test to give time for it to work.

Play specialist

A play specialist may be able to meet with your child. They will use dolls and other toys to help your child prepare for the blood test.

Other tips to help

  • You can stay with your child during the blood test. Ask the person taking the blood whether there is anything you can do to make your child more comfortable.
  • Some children like to count to five before the needle goes in, or tell a story or sing a rhyme during the test.
  • Find out whether your child would like to watch the blood being taken, or whether he or she prefers to look away.
  • Staying calm and confident while distracting your child will help.

Blood samples

Getting a blood sample

Blood is usually taken from areas of the body where the veins are close to the skin – this makes it easier to get a blood sample. These are often in the inside of the elbow or back of the hand.

  • A band is tightly wrapped above where blood will be taken, usually around the arm. This allows the vein to swell with blood.
  • The skin is cleaned with an antiseptic wipe.
  • If anaesthetic is being used it will be put on the skin before the test.
  • A needle is inserted – your child may feel a sharp scratch.
  • The blood sample is drawn up into the container(s) and the needle is removed.
  • A cotton wool pad is often used to stop bleeding and prevent bruising – you or your child may be asked to hold it in place. Sometimes a plaster is put over the site.

Getting a small blood sample

When only a small sample of blood is needed, some hospitals will get it from the capillaries, very tiny blood vessels under the skin. This is usually on the finger, thumb or heel.

  • The skin is cleaned with an antiseptic wipe.
  • A small needle is used to pierce  the fleshy part of the finger, thumb or heel. It is removed straight away.
  • The finger, thumb or heel is squeezed and the blood collected in a small container.
  • A cotton wool pad is usually used to stop bleeding and prevent bruising – you or your child may be asked to hold it in place. Sometimes a plaster is applied.

Complications and risks

When it is difficult to take blood

For most children, taking blood is quick, does not hurt much and is very safe.

Some children have small veins that are difficult to find and take blood from. The person taking your child’s blood will work with you and your child to find the best place to take blood.

Occasionally, he or she will bring a second healthcare professional to help. Sometimes they will need to take blood more than once to make sure they have enough blood for the tests.

Swelling, bruising and pain

Occasionally after a blood test, the site has swelling, bruising or pain. 

  • Put ice on the site. Cover the ice in a bag or a cloth – do not put ice directly on the skin.
  • Speak with your doctor, nurse or pharmacist before giving a painkiller such as paracetamol.

What happens to the blood

The container(s) with your child’s blood is/are labelled with his or her name, and sent to a laboratory. Hospital staff can look at the blood under a microscope or test it with chemicals.

Your doctor or nurse will tell you when and how you get the results.