Iron infusion

Most people get enough iron from eating a healthy, balanced diet. However, sometimes people require extra iron and this can be given as a tablet, or in some cases as an infusion.

An infusion is an injection given over a period of time. It can take from 15 minutes up to several hours. Supplementing iron in this way increases the amount of iron stored in your body and can be used to help to treat or prevent iron deficiency (low blood levels of iron). You can read more about how iron deficiency can happen, who is most at risk of low iron and how it is diagnosed on the iron deficiency page. 

On this page, you can find the following information:

When are iron infusions given?

Low iron levels are usually treated with iron taken orally (by mouth) as tablets or liquid (called oral iron supplements). But in some cases, if oral iron supplements are not suitable, then an iron infusion is given. You may need an iron infusion if you:

  • are unable to take iron tablets or liquid
  • are unable to absorb iron through your gut for example, due to inflammatory bowel disease
  • have lost a lot of blood, during surgery for example
  • need a rapid increase in iron to avoid complications after a blood transfusion or before or after major surgery
  • have ongoing (chronic) kidney disease.

Which iron infusions are available in Aotearoa New Zealand?

There are a few types of iron infusion available. These include:

  • iron polymaltose (Ferrosig®)
  • ferric carboxymaltose (Ferinject®). 

Which type your doctor will prescribe depends on your age, risk factors such as kidney problems, what dose you need and how quickly the iron needs to be given.

How are iron infusions given?

  • Iron infusions are usually given as a slow drip into your vein (called intravenous infusion). A needle is placed into the vein, in the back of your hand or in your arm, so the iron infusion can go directly into your blood stream. Depending on which type is used, it can take 15 minutes or a few hours to have the dose.
  • You may need to have more than 1 dose, in which case the doses will be given at least 7 days apart. Your healthcare team will let you know if this is needed. 
  • Your healthcare team will monitor you closely while you have your infusion. They may record your blood pressure, temperature, heart rate, respiratory rate and look for signs of an allergic reaction.


The dose needed will be different for each person. Your doctor will calculate how much iron is needed to return your iron levels to normal. The dose is based on your body weight and your iron level. The iron will take a few weeks to have its full effect.     

You can be given an iron infusion at your GP surgery, clinic or hospital. On the day of the infusion, eat your meals as usual and take your regular medicines. 

Precautions before having an iron infusion

  • Are you pregnant or breast-feeding? 
  • Do you have problems with your liver or kidneys?
  • Do you have asthma, eczema or other allergies?
  • Have you ever had a reaction to any type of iron injection or infusion in the past?
  • Are you taking any other medicines including over-the-counter or complementary medicines, eg, vitamins, minerals, herbal or naturopathic medicines?

If you answered yes to any of these questions it’s important that you tell your doctor before you are given the treatment. Sometimes a medicine isn’t suitable for a person with certain conditions, or it can only be used with extra care.

After having an iron infusion

If you aren't feeling well after your infusion don't drive or resume your usual activities until you feel better. Call a whānau member or friend to help you.

It can take some time for your iron levels to improve, so your healthcare team will ask you to have a blood test about 6–12 weeks after your treatment. You may need a second treatment if your iron levels are still low.

If you are taking iron tablets, don't take them for a week after an iron infusion because the iron in them will not be absorbed by your body.

What are the side effects of an iron infusion?

Like all medicines, iron infusions can cause side effects, although not everyone gets them. Often side effects improve as your body gets used to the new medicine.  

Side effects What should I do?
  • Changes in the way food tastes 
  • This is temporary and will pass after a few days.
  • Headache
  • Feeling sick (nausea)
  • Vomiting (being sick)
  • Tell your doctor or nurse if these bother you.
  • Take paracetamol for headaches.
  • Feeling dizzy or faint
  • This is quite common while you are having the infusion. Your nurse will measure your blood pressure during the infusion.    
  • Signs of an allergic reaction such as difficulty breathing, rash, hives or itching
  • You will be monitored closely during the infusion and you'll be asked to wait for about half an hour afterwards to make sure you don't have any allergic reactions.
  • People with allergies, asthma, eczema or rheumatoid arthritis may be at increased risk of allergic reactions.
  • If you’re at home and have an allergic response (eg, your face or tongue swelling, collapsing or difficulty breathing) phone 111 for emergency help.
Did you know that you can report a side effect to a medicine to CARM (Centre for Adverse Reactions Monitoring)? Report a side effect to a product

Learn more

The following links provide further information on iron infusions. 

Iron (as polymaltose) NZ Formulary
Intravenous (IV iron)
Healthinfo, NZ 
Ferrinject Consumer Information Sheet, NZ
Venofer Consumer Information Sheet, NZ


  1. Parenteral iron NZ Formulary, NZ 
  2. Ferinject Medsafe Product Information, NZ
  3. Intravenous Ferric Carboxymaltose BPAC, NZ, 2017 
  4. Intravenous iron Safe Rx, NZ
  5. Anaemia on full blood count – investigating beyond the pale BPAC, NZ, 2013
  6. Parenteral iron NZ Formulary, NZ

Additional resources for healthcare professionals

Intravenous iron and hypersensitivity Medsafe, NZ, 2014
Iron IV infusion (clinical skills) Health Navigator NZ
Intravenous iron – safe prescribing – calculate and measure SafeRx, NZ, 2017

Calculators are available online for estimating iron requirements using the Ganzoni formula, eg,

Credits: Sandra Ponen, Pharmacist. Reviewed By: Maya Patel, MPharm PGDipClinPharm, Auckland Last reviewed: 18 Feb 2022