Overview
Intravenous iron infusion
An intravenous (IV) iron infusion is a way of giving a liquid iron preparation directly into your bloodstream through a drip in your arm. It’s sometimes used instead of iron tablets, to increase your iron levels more quickly.
You may need an iron infusion if you:
- have iron deficiency or iron deficiency anaemia
- need to increase your iron levels quickly (for example, before surgery)
Types of iron we use
We usually use a brand of iron called Monofer® for this treatment.
If Monofer is not suitable for you, we may use Ferinject® or Venofer® instead.
We'll let you know the type of iron you'll be given before your treatment.
Before your infusion
Iron infusions are not suitable for everyone.
It's very important that you tell us if:
- you have had a reaction to iron before
- you have any allergies
- you are or may be pregnant
- you have an infection
- you have liver problems
- you have asthma
- you have any other blood conditions
We'll check that it's safe for you to have the infusion.
On the day of your infusion
The nurse will explain the treatment to you, as well as answer any questions you have.
They’ll also check your blood pressure, heart rate and temperature.
Depending on your blood results and the brand of iron used, we may also check your weight.
During treatment
We’ll place a small plastic tube (cannula) into a vein in your arm so that the iron can be given through a drip. This will be removed before you leave.
The infusion usually takes 30 to 45 minutes. After the infusion, you’ll need to stay for about 30 minutes so that we can monitor you for any side effects, such as an allergic reaction.
We’ll also check your blood pressure, temperature and heart rate again.
If you feel well enough, you can leave the hospital after this.
Length of treatment
Some people only need one infusion, but this depends on the type of iron used and your blood results.
The dose (amount) of iron may be based on your weight. You might need another infusion, usually a couple of weeks later, but at least 7 days after your first infusion.
You might need another infusion, usually a couple of weeks later, but at least 7 days after your first infusion.
You’ll need between 3 and 5 infusions for each course of treatment. You can have up to 3 infusions each week, with 1 day in between.
Side effects
Most people feel well after an iron infusion and do not have any serious side effects.
We’ll monitor you throughout your treatment to reduce the risk of any problems.
Please tell the nurses if you feel different after the infusion is started.
Allergic reactions
You might have an allergic reaction during the infusion, but this is uncommon.
Symptoms of an allergic reaction can include:
- a rash
- itching
- an itchy rash (hives)
If this happens we can prescribe medicine to help with this.
If you develop a rash or itching after you have left hospital, it's unlikely to be caused by an allergic reaction. Taking an antihistamine, which you can buy from a pharmacy, should help.
Serious allergic reaction (anaphylaxis)
It's rare to have a serious allergic reaction, called anaphylaxis. This type of reaction can be life threatening. It can cause swelling of your airway, making it difficult to breath, and can lead to low blood pressure. If this happens, it usually starts during the infusion or shortly after, while you are being monitored.
If you have already left hospital and develop symptoms of a serious allergic reaction, you must get emergency help.
Low phosphate levels
There is a risk of developing low phosphate levels. This is more likely if you are having repeated high-dose Ferinject infusions. For most people, this does not cause problems. In rare cases, very low phosphate levels can lead to weak bones and sometimes fractures. You might be tested for this, and treatment will be offered if needed.
Low phosphate levels usually cause symptoms 1 to 2 weeks after the infusion.
Contact the haematology day unit or your GP if:
- you get tiredness, muscle pain or bone pain that appears or continues for 1 to 2 weeks
- your symptoms are severe
Skin discolouration or staining
There is a risk that iron may leak out of the vein under your skin during the infusion. This can cause a brown stain at the treatment site.
Stains can vary in size depending on how much iron has leaked and could be significant.
There is also a risk that you may develop changes to your skin colour elsewhere on your body. This is not caused by iron leaking from the vein. It may darken your overall complexion or appear as brown patches on visible areas of your skin.
Both types of skin discolouration can be permanent or may take a long time to fade. We can refer you to dermatology for further advice, but treatment options are limited.
Other side effects
You may have some side effects during or after the infusion. These usually last for a maximum of 2 to 4 days:
- headache or feeling dizzy
- feeling sick (nausea) or being sick (vomiting)
- a delayed rash or skin redness (this may be harder to see on brown or black skin)
- diarrhoea (runny poo) or constipation (finding it hard to poo)
- low or high blood pressure
- abnormal liver function
- a reaction at the injection site
- pain in your chest, tummy or back
- a feeling of tightness in your chest
- breathlessness
- hot flushes or a fever
- muscle aches or pains (this can cause a flu-like feeling)
Let the nurse know if you have any of these symptoms during treatment.
After your infusion
Do not take iron tablets or supplements fo 5 days after your infusion as they will not be effective.
If you're having an infusion to prepare for surgery, or if you were severely anaemic before the infusion, your nurse may arrange a blood test 4 to 6 weeks after the infusion to check your iron levels. This depends on the type of iron used. If your iron levels are still low, you may need another infusion.
When to get help
Go to your nearest emergency department (A&E) or call 999 if:
- you develop any chest pain
- your lips, mouth, throat or tongue suddenly become swollen
- you're breathing very fast or finding it hard to breathe (you may become wheezy or feel like you are choking or gasping for air)
- your throat feels tight or you're struggling to swallow
- your skin, tongue or lips turn blue, grey or pale. If you have black or brown skin, this may be easier to see on the palms of your hands or the soles of your feet
- you suddenly become very confused, very drowsy or dizzy
- you feel like you may faint or collapse
Resource number: 4691/VER3
Last reviewed: March 2026
Next review due: March 2029
