Iron treatment in inflammatory bowel disease

Inflammatory bowel disease (IBD) is a term used to describe medical conditions such as:

These are long-term conditions involving inflammation of the gut.

Iron deficiency anaemia is caused by lack of iron and commonly occurs in patients with a variety of medical conditions including IBD. Iron supplements are used to increase your iron levels and treat iron deficiency anaemia. Iron is available in different forms that can be taken by mouth (orally), or by an injection in your arm (intravenous infusion).

The form that will be recommended to you will depend on how severe your iron deficiency anaemia is and your treatment history.

If your iron levels are not too low, it is best to try an iron tablet or liquid first. Taking the medicine once a day has been shown to be the most beneficial for patients with IBD. 

Let us know if you do not get on with the standard iron tablets or liquid. There is an alternative iron tablet (ferric maltol, Feraccru®) we may be able to recommend for you instead.

If you do not get on with any of these, or your iron deficiency is severe, we will arrange for you to have an iron infusion.

Before you start taking iron 

You will need a few blood tests before you start. We will also monitor the effects after you receive the treatment. These blood tests also help us decide which form is best for you. These may include tests to check:

  • full blood count
  • iron studies
  • vitamin B12 and folate

How to take the medicine

Iron tablets

These are available as different salts:

They are taken once a day. If you have any side effects, you may be advised to take the tablets on alternate days.

Iron tablets should be swallowed whole with a glass of water or preferably with orange juice. You should be sitting upright or standing. Take them after food and do not crush or chew them.

Iron liquid (sodium feredetate)

This can be recommended as an alternative to tablets and is also taken once a day or on alternate days.

Ferric maltol (Feraccru®)

If you cannot tolerate iron tablets or liquid, you may be advised to try ferric maltol (Feraccru®). This form of iron can cause less side effects in patients with IBD. This is taken twice a day.

Iron infusion (Monofer® or Ferinject®)

This is a liquid solution, given slowly through a vein in the arm. It will usually be given in 1 or 2 visits to our IBD infusion unit.

It is not suitable if:

  • you have a known allergy to iron supplements
  • you have a liver problem
  • you are in the first trimester of pregnancy

If you forget to take a dose

If you forget to take your iron, you can take it in the following day or 2 days later.

Do not double your dose if you have forgotten.

Try not to forget any doses. Iron works slowly and therefore if you regularly forget the medicine, you will have a lower level in your blood. This can make it less effective.

Getting a repeat prescription

Iron tablets and liquid (ferrous sulphate, ferrous sulphate and sodium feredate) can be prescribed by your GP.

After your hospital specialist has started you on ferric maltol (Feracrru®), they will advise your GP what dose to prescribe.

Taking iron with other medicines

Iron supplements can interact with other medicines.

Before you start taking iron, please let your doctor know about all the medicines you take. This should include anything prescribed for you and any medicines you buy from a pharmacy or shop (including herbal and homeopathic).

Side effects

Iron tablets and liquid

These often cause side effects. The more common side effects (affecting up to 1 in 10 people) include:

  • feeling sick (nausea) and being sick (vomiting)
  • stomach discomfort or heartburn
  • losing your appetite
  • diarrhoea
  • constipation
  • darker poo than usual
  • black stained teeth (from the liquid only)

If you have side effects, we advise you to reduce the dose by taking it on alternate days. Or contact us to change to an alternative form of medicine.

Ferric maltol (Feraccru®)

This is less likely to cause the side effects listed above but they can still occur. It is not very common but it can also cause:

  • headaches
  • stiffness in your joints
  • changes to your skin

Iron infusion (Monofer® or Ferinject®)

There is a risk of an allergic reaction, ranging from mild to severe. This is not common and can affect less than 1 in 100 people.

There is also a risk of a low phosphate level, particularly in people having recurring high dose Ferinject infusions. For most people, this does not have any significant risk. However, in rare cases, a very low phosphate level can lead to weak bones and sometimes fractures. You might be tested for this and treatment might be offered.

Get medical advice if you have worsening fatigue (tiredness) with muscle or bone pain.

Report any symptoms to the nurse while you are having treatment. If some of the iron leaks outside the vein during the infusion, it can cause a permanent stain or change of colour to your skin. However, this is rare.

You should not take iron tablets or supplements for 5 days after your Ferinject infusion.

Contact the IBD advice line if you have any of these side effects.

Pregnancy and breast feeding

Iron tablets (ferrous sulphate, ferrous fumarate, ferrous gluconate) and ferric maltol, (Feracrru®) can be used in pregnancy and breastfeeding.

Iron infusion (Monofer® or Ferinject®) given intravenously is avoided in the first trimester of pregnancy.

Drinking alcohol

We recommend you keep well within the national recommended limits of alcohol (maximum of 14 units per week).

14 units is about the same as 6 pints of average-strength beer or 10 small glasses of lower-strength wine.

Any amount of alcohol can damage the liver, especially if you have an underlying condition. Depending on the state of your liver, your clinician may ask you to avoid alcohol completely.

Useful information

Crohn’s and Colitis UK has more information about IBD www.crohnsandcolitis.org.uk

Resource number 5460/VER1
Published date: January 2024
Review date: January 2027


Contact us

If you have any questions or concerns about your treatment and condition:

Email the IBD advice line: [email protected]

Please include your name, hospital number, contact details and details of your enquiry. We will respond 9am to 5pm Monday to Friday.

If you are concerned outside these hours, please contact your GP or call NHS 111.

If you have any questions or concerns about your medicine, email the IBD pharmacy team: [email protected]

You can also call the gastroenterology department during office hours. Phone: 020 7188 2499 or 020 7188 1222

Do you have any comments or concerns about your care?

Contact our Patient Advice and Liaison Service (PALS)

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