Iron infusion

Key points about iron infusions

  • Most people get enough iron from eating a healthy, balanced diet. However, sometimes people need extra iron and this can be given as a tablet, or in some cases as an infusion.
  • An iron infusion is an iron injection given slowly into your bloodstream through a vein. This method is also called an intravenous or IV infusion.
  • Examples of iron infusions include iron polymaltose (Ferrosig®) and ferric carboxymaltose (Ferinject®).
  • Find out how to have it and possible side effects.
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An iron infusion is an iron injection given into your bloodstream through a vein. It is also called intravenous or IV.  The infusion is given slowly and can take from 15 minutes up to several hours depending on the type of iron used. 

Giving iron in this way increases the amount of iron stored in your body and can be used to help to treat iron deficiency (low levels of iron in your blood).

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 (eg, kidney problems), what dose you need and how quickly the iron needs to be given.

The most common way to treat low iron levels is to take iron taken tablets or liquid (called oral iron supplements). This works well for most people and is usually tried first. But if oral iron supplements are not suitable, or don’t work as well or as quickly as needed, 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, eg, after a severe injury
  • need a rapid increase in iron to avoid complications after a blood transfusion or before or after major surgery
  • have ongoing (chronic) kidney disease or heart failure.

You can be given an iron infusion at your GP surgery, clinic or hospital.

  • 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 will need to stay for at least 30 minutes after the infusion has finished, to check you don't have any side effects.
  • Your healthcare team will monitor you closely while you have your infusion and check on you afterwards. They may record your blood pressure, temperature, heart rate and respiratory rate, and look for signs of an allergic reaction.


The dose needed will be different for each person. Your doctor or midwife will calculate how much iron you need.

  • The dose is based on your body weight and your iron level.
  • Sometimes, to get your iron to a normal level, you may be given a second infusion 7 days or more later, or you may need to take iron tablets for a few months. If you take iron tablets, you should not start it for at least one week after the infusion.
  • The iron infusion will take a few weeks to have its full effect.
  • You will need to have a blood test to see how you are responding.

How do I prepare for the infusion?

No particular preparation is needed for an iron infusion.

  • You don't need to fast (go without food), so have your usual breakfast or lunch.
  • Take all your regular medicines.
  • Drink plenty of fluids – this makes it easier to find a vein for the drip/infusion.
  • If you're feeling well, you will be able to drive home after your 30 minutes observation time following the iron infusion. You may feel dizzy, confused or light-headed after being given IV iron. If this happens, let the doctor or nurse know and  and don't drive or use any tools or machinery until you feel better.

If you could be pregnant, let your doctor or midwife know as IV iron should be avoided in the first trimester in pregnancy.

There is a chance of having an allergic reaction which can, in rare cases, be life threatening. Let your doctor or nurse know if you have asthma, eczema or other allergies or if you've had a reaction to any type of iron injection or infusion in the past. 

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

Very rarely, iron infusion can cause changes in skin colour near where the injection is given. See the 'Side effects' section for more information.

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're taking iron tablets, ask your doctor when you should start taking them again. You should generally not take them for at least a week after an iron infusion because the iron in them will not be absorbed by your body.

Like all medicines, iron infusions can cause side effects, although not everyone gets them. Often side effects improve over time.

Risk of skin staining – change in skin colour

Very rarely, iron infusions can cause changes in skin colour in the area around where the infusion was given. This is called skin staining and may occur when there is a leakage of iron into the skin during the infusion. Tell your doctor or nurse straight away if you notice discomfort, burning, redness, swelling or a change in skin colour during the infusion.

  • The change in colour is usually light to dark brown but in some people it may be blue, black, purple or grey.
  • The risk of skin staining is higher if you have multiple doses.
  • Usually, the staining isn't painful, but some people find it can cause aching or sensitive skin.
  • In many cases iron staining is permanent. Some people may notice fading of the stain over time or after treatment with laser therapy.

Other side effects

Side effects What should I do?
  • Changes in the way food tastes 
  • This is temporary and will pass after a few days.
  • Mild fever
  • Headache
  • Feeling sick (nausea)
  • Vomiting (being sick)
  • Muscle and joint ache or pain
  • 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.
  • Don't drink alcohol, and don't drive or operate machinery until you feel better.
  • Burning and swelling at the injection site
  • Tell your doctor or nurse.
  • Signs of low phosphate such as vertigo, nausea, general weakness, tingling in the hands, bone pain, low mood (depression like symptoms) and confusion.
  • Ferric carboxymaltose (Ferinject®) infusion may rarely cause low phosphate levels. 
  • In most cases this is mild and passes with no symptoms.
  • Tell your doctor immediately or ring Healthline 0800 611 116. 
  • 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 signs of an allergic reaction, phone 111 for emergency help or go to your nearest emergency department immediately.
Did you know that you can report a medicine side effect to CARM (Centre for Adverse Reactions Monitoring)? Report a side effect to a product.(external link)

The following links provide further information on iron infusions. 

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


Intravenous (IV) Iron Infusion booklet [PDF, 880 KB] Health New Zealand | Te Whatu Ora, 2021

5 questions to ask about your medications(external link) Health Quality and Safety Commission, NZ, 2019 English(external link), te reo Māori(external link)


  1. Parenteral iron(external link) NZ Formulary, NZ 
  2. Ferinject(external link) Medsafe Product Information, NZ
  3. Intravenous Ferric Carboxymaltose(external link) BPAC, NZ, 2017 
  4. Intravenous iron(external link) Safe Rx, NZ
  5. Anaemia on full blood count – investigating beyond the pale(external link) BPAC, NZ, 2013
  6. Infusing iron? Consider phosphate(external link) Medsafe, NZ, 2018 
  7. Intravenous iron preparations and potential for skin staining(external link) New South Wales Health, 2023 
  8. A stain on iron therapy(external link) Australian Prescriber 2020 


Intravenous (IV) Iron Infusion booklet
Health New Zealand | Te Whatu Ora, 2021

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Credits: Sandra Ponen, Pharmacist, Healthify He Puna Waiora. Healthify is brought to you by Health Navigator Charitable Trust.

Reviewed by: Angela Lambie, Pharmacist, Auckland

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