Iron supplements for babies and children

Iron is important for brain development and making new red blood cells to prevent a low red blood cell count. Find out about when your baby or child may need an iron supplement (ferrous sulphate) and how to give it.

On this page you will find information about:

What is iron for?

Iron is vital for body function. It is especially important for brain development and making new red blood cells to prevent a low red blood cell count (anaemia). Read more about iron.

Why do some children need extra iron?

Iron supplements are use to prevent or treat a lack of iron (iron deficiency). This can cause anaemia. Babies and children with anaemia are often pale and tired. They may not grow and develop properly. Iron supplements help your child to make more haemoglobin and increase their iron stores. 


In the last few months of pregnancy, your baby stores iron in their body to use after they are born. Well-grown, full-term babies have stored enough iron to use until they are 6 months old.

Premature babies (who are born early, before 36 weeks) or babies who are small (who weigh less than 2.5 kg at birth) do not have as much iron stored in their body. What iron they do have is used up as they grow. They need extra iron to prevent iron deficiency. Breast milk contains very little iron.


Low iron in children can be caused by not getting enough iron in their diet, having problems with how their body absorbs iron (such as in coeliac disease), or blood loss such as in inflammatory bowel disease.

Examples of iron supplements

Examples of liquid iron supplements available in New Zealand include ferrous sulfate or Ferodan liquid. Tablet forms are available for older children. Read more about iron tablets.   

How much iron does my child need?

Your child's iron dose depends on their weight. Your doctor may increase the dose as your child grows and gains weight.  

Iron may be prescribed once or twice daily. Your doctor or pharmacist will tell you how much to give your child.

How long will my child need iron?

It's recommended that you start giving iron when your baby is between 4 and 6 weeks old. Depending on how premature your baby was, you may need to start giving iron in hospital, or you may start giving it after you go home. Keep giving iron each day until your child's first birthday or your doctor asks you to stop.

How do I give iron to my child?

Always use a proper measuring cup, spoon or syringe to give the correct dose – don’t use a kitchen spoon. Some liquid medicines come with their own measuring cup, spoon or syringe or you can buy one from your pharmacy. Read more tips on how to give medicines to babies and children and how to use a medicine syringe.

Iron absorbs better on an empty stomach so try to give it 30 minutes before a feed or a meal or 1 hour after a feed or a meal.

What if my child vomits?

If your child vomits less than 30 minutes after giving the iron, give the same dose again. If it is more than 30 minutes, do not give another dose until it is next due.

How will the iron affect my child?

Your child may react to the taste, but this does not mean it is a problem. Your child's poo (bowel motions) may become a darker colour, but this is harmless. The poo can become a little firmer and some children become constipated when they first start taking iron, but this usually settles. If your child vomits or spits up this may also be a darker colour.

When should the iron start working?

It takes 3 to 4 weeks for the iron stores to build up in the body. Usually iron needs to be taken for at least 3 months for it to have full benefit. 

Where should I store the iron?

Keep the medicine in its container and out of reach of children. It is a good idea to store it in a cupboard, away from heat and direct sunlight. You do not need to keep it in the fridge. The syrup is normally colourless, but if the colour varies from bluish green to gold this is OK.


  1. Iron (ferrous sulphate) for premature and small babies KidsHealth, NZ
  2. Iron deficiency Starship, NZ
Credits: Sandra Ponen, Pharmacist. Last reviewed: 08 Apr 2021