Iron supplements

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Only take iron supplements if they have been recommended to you in order to treat anaemia. (Anaemia is a condition where a lack of iron in the body leads to a reduction in the number of red blood cells).

How do the supplements work?

Iron is needed for the production of haemoglobin, which is an essential ingredient in red blood cells. Haemoglobin is very important as it carries oxygen from the lungs to the rest of the body.

If you don’t have enough iron, you can develop anaemia, which means that you aren’t making enough red blood cells to carry oxygen around your body. You may become breathless, tired and have a lack of energy, your skin may become pale and you may have palpitations (noticeable heartbeats).

Which types of iron supplements are available?

The main types of iron supplements used are:

• Ferrous sulphate (high strength tablets)

• Ferrous fumarate (high strength tablets or syrup)

• Ferrous gluconate (medium strength tablets)

• liquid iron supplements (low strength) for women who experience constipation in relation to higher strength versions

How do I take them?

You should take your iron supplements on an empty stomach (preferably one hour before a meal) with a drink containing vitamin C, such as a glass of orange juice or another juice drink with added vitamin C. New evidence has shown that taking iron supplements every other day can increase their effectiveness. The precise instructions for when to take your supplements will be discussed with you by the healthcare professional who prescribes them.

Why is the way I take them important?

Absorption of iron from the gut is reduced by food, tea and milk, so these should be avoided for one hour before and after taking the iron supplement.

Some medications also affect absorption of iron from the gut, particularly medications which reduce stomach acid (antacids) and certain antibiotics. Always check with your doctor or pharmacist whether any of your other medicines might affect how your iron supplement works.

The only factor that improves the absorption of iron is vitamin C. This is why we recommend that you take your iron supplement with a drink containing vitamin C.

What side effects might I get?

The following side effects are common:

• stomach upset

• nausea (feeling sick)

• stomach ache

• diarrhoea

• constipation

These usually improve as your body gets used to the iron supplements. If the side effects continue to be a problem for you, contact the healthcare professional who prescribed the iron supplements. They may suggest reducing the strength of your supplements or the frequency that you are taking them.

What happens now?

You will be asked to have a repeat blood test three to six weeks after you start taking your iron supplement, to check for a response to the treatment.

Click here for a useful link with more information.


Improving the physical and emotional health and wellbeing of expectant mothers, infants, children and young people throughout Aneurin Bevan University Health Board Area.

(N.B: The Family and Therapies team at ABUHB is NOT responsible for the content on the webpage links that we refer to in our resource sections and linked information to external sites. All information was accurate and appropriate at the time the webpage was created.)

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