NZ Formulary

Iron supplements

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What does it do?

Iron supplements are used to treat and prevent some types of anaemia. They increase the amount of iron in your body.

Before you start

  • Tell your doctor if you have liver, kidney, stomach or bowel problems.
  • Tell your doctor if you are pregnant, planning to become pregnant, or breastfeeding.

How should you take it?

Take iron supplements regularly as directed.
Tablet: Swallow whole, with food and a glass of water.
Liquid: Measure carefully with an oral syringe or measuring spoon.

What if you forget a dose?

If it is nearly time for your next dose, skip the missed dose and take your next dose at the usual time. Otherwise, take the missed dose as soon as you remember. Do not take two doses at the same time.

Can you take other medicines?

Some medicines available without a prescription may react with iron supplements including:

  • antacids (e.g. Mylanta®) or supplements containing aluminium (e.g. Alu-Tab®), calcium (e.g. Calci-Tab®), magnesium (e.g. Chelated Magnesium®) or zinc (e.g. Zincaps®) – do not take these within two hours of iron supplements
  • supplements that also contain iron (e.g. Centrum®)

Tell your pharmacist or doctor about all medicines or treatments that you may be taking, including vitamins, herbal products or recreational drugs.

What side effects might you notice?

Side EffectsRecommended action

Nausea, constipation, diarrhoea

Tell your doctor if troublesome

Staining of the teeth (with the liquid)

Place the liquid on the back of the tongue with a dropper; use a straw; or brush your teeth after each dose

If you notice any other effects, discuss them with your doctor or pharmacist.

Other information:

  • Iron supplements may darken your bowel motions. This is common and usually nothing to worry about, but can also be a sign of bleeding – discuss with your doctor.
  • Iron supplements are also known as ferrous fumarate or ferrous sulfate.