About iron deficiency anaemia

Iron deficiency anaemia is a condition where a lack of iron in the body leads to a reduction in the number of red blood cells.

Iron is used to produce red blood cells, which help store and carry oxygen in the blood. If you have fewer red blood cells than is normal, your organs and tissues won't get as much oxygen as they usually would.

There are several different types of anaemia, and each one has a different cause. Iron deficiency anaemia is the most common type.

Other types of anaemia can be caused by a lack of vitamin B12 or folate in the body – read more about vitamin B12 and folate deficiency anaemia.

Symptoms of iron deficiency anaemia

Many people with iron deficiency anaemia only have a few symptoms. The severity of the symptoms largely depends on how quickly anaemia develops.

You may notice symptoms immediately, or they may develop gradually if your anaemia is caused by a long-term problem, such as a stomach ulcer.

The most common symptoms include:

  • tiredness and lack of energy (lethargy)
  • shortness of breath
  • noticeable heartbeats (heart palpitations)
  • a pale complexion

Less common symptoms include:

  • headache 
  • hearing sounds that come from inside the body, rather than from an outside source (tinnitus)
  • an altered sense of taste
  • feeling itchy
  • a sore or abnormally smooth tongue
  • hair loss
  • a desire to eat non-food items, such as ice, paper or clay (pica)
  • difficulty swallowing (dysphagia)
  • painful open sores (ulcers) on the corners of your mouth
  • spoon-shaped nails

When to see your GP

See your GP if you experience symptoms of iron deficiency anaemia. They should be able to diagnose the condition using a simple blood test.

Read more about diagnosing iron deficiency anaemia

What causes iron deficiency anaemia?

There are many things that can lead to a lack of iron in the body. In men and post-menopausal women, the most common cause is bleeding in the stomach and intestines.

This can be caused by a stomach ulcer, stomach cancer, bowel cancer, or by taking non-steroidal anti-inflammatory drugs (NSAIDs).

In women of reproductive age, heavy periods and pregnancy are the most common causes of iron deficiency anaemia as your body needs extra iron for your baby during pregnancy.

Unless you're pregnant, it's rare for iron deficiency anaemia to be caused just by a lack of iron in your diet. However, if you do lack dietary iron, it may mean you're more likely to develop anaemia than if you have one of the problems mentioned above.

Read more about the causes of iron deficiency anaemia

How iron deficiency anaemia is treated

Treatment for iron deficiency anaemia involves taking iron supplements to boost the low levels of iron in your body. This is usually effective, and the condition rarely causes long-term problems.

You'll need to be monitored every few months to check the treatment is working and your iron levels have returned to normal.

The underlying cause will need to be treated so you don't get anaemia again. Increasing the amount of iron in your diet may also be recommended.

Good sources of iron include:

  • dark-green leafy vegetables, such as watercress and curly kale
  • iron-fortified cereals or bread
  • brown rice 
  • pulses and beans
  • nuts and seeds
  • meat, fish and tofu
  • eggs
  • dried fruit, such as dried apricots, prunes and raisins

Read more about treating iron deficiency anaemia

Further problems

If iron deficiency anaemia is left untreated, it can make you more susceptible to illness and infection, as a lack of iron affects the body's natural defence system (the immune system).

Severe iron deficiency anaemia may increase your risk of developing complications that affect the heart or lungs, such as an abnormally fast heartbeat (tachycardia) or heart failure, where your heart is unable to pump enough blood around your body at the right pressure.

Pregnant women with severe or untreated anaemia also have a higher risk of complications before and after birth.

Read more about the complications of iron deficiency anaemia

Causes of iron deficiency anaemia

Iron deficiency anaemia occurs when the body doesn't have enough iron, leading to the decreased production of red blood cells. Red blood cells carry oxygen around the body.

A lack of iron can be caused by several factors. Some of the most common causes of iron deficiency anaemia are outlined below.

Monthly periods

In women of reproductive age, periods are the most common cause of iron deficiency anaemia.

Usually, only women with heavy periods develop iron deficiency anaemia. If you have heavy bleeding over several consecutive menstrual cycles, it's known as menorrhagia.


It's also very common for women to develop iron deficiency during pregnancy.

This is because your body needs extra iron to ensure your baby has a sufficient blood supply and receives necessary oxygen and nutrients. 

Some pregnant women require an iron supplement, while others may need to increase the amount of iron in their diet.

Read more about vitamins and minerals in pregnancy

Gastrointestinal blood loss

The gastrointestinal tract is the part of the body responsible for digesting food. It contains the stomach and intestines.

Bleeding in the gastrointestinal tract is the most common cause of iron deficiency anaemia in men, as well as women who've experienced the menopause (when monthly periods stop).

Most people with gastrointestinal bleeding don't notice any obvious blood in their stools and don't experience any changes in their bowel habits.

Some causes of gastrointestinal bleeding are described below.

Non-steroidal anti-inflammatory drugs

Non-steroidal anti-inflammatory drugs (NSAIDs) can cause bleeding in the stomach. Ibuprofen and aspirin are two commonly prescribed NSAIDs.

If your GP thinks your medication is causing gastrointestinal bleeding, they can prescribe a less harmful medicine. However, don't stop taking a medicine you've been prescribed unless your GP advises you to.

Stomach ulcers

The acid in your stomach, which helps your body digest food, can sometimes eat into your stomach lining. When this happens, the acid forms an open sore (an ulcer). This is also known as a stomach ulcer or a peptic ulcer.

Stomach ulcers can cause the stomach lining to bleed, which can lead to anaemia. In some cases, the bleeding can cause you to vomit blood or pass blood in your stools. However, if the ulcer bleeds slowly, you may not have any symptoms.

Gastrointestinal cancer

In a few cases, gastrointestinal bleeding can be caused by cancer, usually stomach cancer or bowel cancer.

When trying to establish the cause of anaemia, your GP will check for possible signs of cancer.

If your GP suspects cancer, you'll be referred to a gastroenterologist (a specialist in treating digestive conditions) for a more thorough examination. This means that if cancer is found, it can be treated as quickly as possible.

If you're 60 years old or over and have iron deficiency anaemia, your GP should refer you to a specialist to rule out bowel cancer. Your  appointment with the specialist should be within two weeks of your GP referring you.


Gastrointestinal bleeding can also be caused by a condition called angiodysplasia. This is the result of abnormal, fragile superficial blood vessels in the gastrointestinal tract, which can cause bleeding.

Chronic kidney disease

People with chronic kidney disease (CKD) often develop iron deficiency anaemia.

Most people with CKD who have iron deficiency anaemia will be given iron supplement injections, although daily tablets may be tried first.

You can read more about treating anaemia in people with CKD on the National Institute for Health and Care Excellence (NICE) website.

Other causes

Other conditions or actions that cause blood loss and may lead to iron deficiency anaemia include:

  • inflammatory bowel disease – a condition that causes redness and swelling (inflammation) in the digestive system, such as Crohn's disease and ulcerative colitis 
  • oesophagitis – inflammation of the gullet (oesophagus) caused by stomach acid leaking through it
  • schistosomiasis – an infection caused by parasites, mainly found in sub-Saharan Africa
  • blood donation – donating a large amount of blood may lead to anaemia
  • trauma – a serious accident, such as a car crash, may cause you to lose a large amount of blood 
  • nosebleeds – having regular nosebleeds may lead to anaemia, although this is rare
  • haematuria (blood in your urine) – but this rarely causes anaemia and may be a symptom of another condition


Malabsorption is when your body can't absorb iron from food, and is another possible cause of iron deficiency anaemia.

This may happen if you have coeliac disease, a common digestive condition where a person has an adverse reaction to gluten, or surgery to remove all or part of your stomach (gastrectomy).

Lack of iron in your diet

Unless you're pregnant, it's rare for iron deficiency anaemia to be caused solely by a lack of iron in your diet.

However, a lack of dietary iron can increase your risk of developing anaemia if you also have any of the conditions mentioned above.

Some studies suggest vegetarians or vegans are more at risk of iron deficiency anaemia because of the lack of meat in their diet.

If you are vegetarian or vegan, it is possible to gain enough iron by eating other types of food, such as:

  • beans
  • nuts
  • dried fruit, such as dried apricots
  • wholegrains, such as brown rice
  • fortified breakfast cereals
  • soybean flour
  • most dark-green leafy vegetables, such as watercress and curly kale

If you're pregnant, you may need to increase the amount of iron-rich food you consume during pregnancy to help prevent iron deficiency anaemia.

Read more about vegetarian and vegan diets

Diagnosing iron deficiency anaemia

See your GP if you experience symptoms of iron deficiency anaemia, such as tiredness, shortness of breath and heart palpitations.

A simple blood test can usually confirm the diagnosis.

Your GP may also carry out a physical examination and ask you a number of questions to help determine the cause of your anaemia.

Blood test

To diagnose iron deficiency anaemia, a blood sample is taken from a vein in your arm and a full blood count is made. This means all the different types of blood cells in the sample will be measured.

If you have anaemia:

  • your levels of haemoglobin – a substance that transports oxygen – will be lower than normal
  • you'll have fewer red blood cells, which contain haemoglobin, than normal
  • your red blood cells may be smaller and paler than usual

Your GP may also test for a substance called ferritin, a protein that stores iron. If your ferritin levels are low, it means there isn't much iron stored in your body and you may have iron deficiency anaemia.

Read more about blood tests 

Vitamin B12 and folate deficiency

If your GP thinks your anaemia may be the result of a vitamin B12 and folate deficiency, the levels of these substances may be tested. Folate works with vitamin B12 to help your body produce red blood cells.

Vitamin B12 and folate deficiency anaemia is more common in people who are over the age of 75.

Finding the cause

To determine the underlying cause of your anaemia, your GP may ask questions about your lifestyle and medical history. For example, they may ask you about:

  • your diet – to see what you typically eat and whether this includes any iron-rich foods
  • any medicines you take – to see if you've been regularly taking a type of medicine that can cause bleeding from the stomach and intestines (gastrointestinal bleeding), such as ibuprofen or aspirin
  • your menstrual pattern – if you're a woman, your GP may ask if you've been experiencing particularly heavy periods
  • your family history – you'll be asked if your immediate family has anaemia or a history of gastrointestinal bleeding or blood disorders

Iron deficiency anaemia is common during pregnancy. If you're pregnant, your GP will usually only look for an alternative cause if a blood test has identified a particularly low haemoglobin level, or if your symptoms or medical history suggest your anaemia may be caused by something else.

Physical examination

A physical examination will usually only be needed if the cause of your iron anaemia deficiency hasn't been identified by examining your medical history and asking you about your symptoms.

In such cases, your GP may:

  • examine your stomach (abdomen) to check for any physical signs of gastrointestinal bleeding
  • look for signs of heart failure, such as swollen ankles – heart failure can have some similar symptoms to iron deficiency anaemia

Two other possible types of physical examination you may have are explained below.

Rectal examination

A rectal examination is usually only needed if you're bleeding from your bottom. It's a common procedure that can help your GP find out if there's something in your gastrointestinal tract that's causing bleeding.

Your GP will insert a lubricated gloved finger into your bottom to feel for any abnormalities.

A rectal examination isn't something to be embarrassed about, as it's a procedure your GP will be used to doing. It shouldn't cause significant pain, but it may cause some slight discomfort – this will only last for a minute.

Pelvic examination

Women may have a pelvic examination if their GP thinks heavy menstrual bleeding (menorrhagia) may be the cause of their anaemia.

During a pelvic examination, your GP will examine your vulva and labia (external sex organs) for signs of bleeding or infection.

They may also examine you internally. This will involve your GP inserting lubricated gloved fingers into your vagina to feel whether your womb (uterus) is tender or enlarged.

A pelvic examination won't be carried out without your consent (permission), and you can choose to have someone with you.

Referral to a specialist

In some cases, your GP may refer you to a gastroenterologist, a specialist in treating digestive conditions. They'll carry out a more thorough examination.

For example, you may be referred to a gastroenterologist if your GP can't identify a cause and you have a particularly low haemoglobin level, or if your GP thinks there's a possibility your symptoms could be caused by stomach cancer or bowel cancer, although this is unlikely.

If you're a woman with heavy periods, you may be referred to a gynaecologist if you don't respond to treatment with iron supplements.

Treating iron deficiency anaemia

Treatment for iron deficiency anaemia usually involves taking iron supplements and changing your diet to increase your iron levels, as well as treating the underlying cause.

Iron supplements

Your GP will prescribe an iron supplement to restore the iron missing from your body. The most commonly prescribed supplement is ferrous sulphate, which is taken as a tablet, usually twice a day.

Some people can experience side effects when taking iron supplements, including:

These side effects should settle down over time. However, your GP may recommend taking the tablets with food or shortly after eating if you have troublesome side effects.

Your GP may also advise you to only take one or two tablets a day, instead of three, if you're finding side effects difficult to cope with.

If you can't take ferrous sulphate because you get severe side effects, you may be prescribed a different iron supplement called ferrous gluconate.

This supplement should cause fewer side effects because it contains a less concentrated dose of iron. However, it may take longer for the iron levels in your body to be restored.

In a few cases – for example, if you have chronic kidney disease (CKD) – iron injections may be recommended instead of tablets.

As with all medications, it's important to store iron supplements out of the reach of children. An overdose of iron supplements in a young child can be fatal.

Dietary advice

If a lack of iron in your diet is thought to be contributing to your iron deficiency anaemia, your GP will tell you how to up your intake.

Iron-rich foods include:

  • dark-green leafy vegetables, such as watercress and curly kale
  • iron-fortified cereals or bread
  • brown rice 
  • pulses and beans 
  • nuts and seeds
  • white and red meat 
  • fish 
  • tofu
  • eggs 
  • dried fruit, such as dried apricots, prunes and raisins

Your diet should include foods from all the major food groups to ensure it's healthy and balanced. In particular, food and drink containing vitamin C are important as vitamin C helps your body absorb iron.

However, consuming large amounts of some foods and drinks, as well as certain medicines, may make it harder for your body to absorb iron. These include:

  • tea and coffee
  • calcium – found in dairy products, such as milk 
  • antacids and proton pump inhibitors (PPIs) – medications used to relieve indigestion
  • wholegrain cereals – although wholegrains are a good source of iron themselves, they contain phytic acid, which can stop your body absorbing iron from other foods and pills

You may be referred to a nutrition specialist called a dietitian if you're finding it difficult to include iron in your diet. They'll be able to give you detailed, personalised advice about how you can improve your diet.

Treating the underlying cause

Your GP will also need to ensure the underlying cause of your anaemia is treated so it doesn't happen again.

For example, if non-steroidal anti-inflammatory drugs (NSAIDs) are causing bleeding in your stomach, your GP may prescribe a different medicine to help minimise the risk of stomach bleeding.

Heavy periods can be treated with medication or – in particularly severe cases – surgery.


Your GP will ask you to return two to four weeks after you've started taking iron supplements to check how well you've responded to the treatment. You'll have a blood test to check your haemoglobin levels.

If your blood test results show an improvement, you'll be asked to continue taking iron supplements and return in two to four months for another blood test.

Once your haemoglobin levels and red blood cells are normal, your GP will usually recommend continuing to take iron supplements for three months to help build up the iron levels in your body.

After this, you should be able to stop taking the supplements, depending on the cause of your iron deficiency anaemia. Your condition will be monitored every three months over the course of a year, and again a year later.

Continuing treatment

Sometimes after a person's iron levels have been replenished, they start to fall again.

This could happen if you don't get enough iron in your diet, you're pregnant, or you have consistently heavy periods.

In such cases, you may be prescribed an ongoing iron supplement to help stop your anaemia returning. This will usually be a tablet, which you'll have to take once a day. 

If treatment is ineffective

If your iron levels don't improve, your GP will ask how regularly you've been taking your iron supplements.

Some people are put off taking the medication because of the side effects. However, your condition won't improve if you don't take the supplements.

If you've been taking the supplements as prescribed and your iron levels still haven't improved, your GP may refer you to a specialist for an assessment.

Complications of iron deficiency anaemia

Iron deficiency anaemia rarely causes serious or long-term complications, although some people with the condition find it affects their daily life.

Some common complications are outlined below.


Iron deficiency anaemia can make you feel tired and lacking in energy (lethargic). This may result in you being less productive at work, and you may find it difficult to stay awake or not feel able to exercise regularly.

Increased risk of infections

Research has shown iron deficiency anaemia can affect your immune system – the body's natural defence system. This increases your vulnerability to infection.

Heart and lung problems

Adults with severe anaemia may be at risk of developing complications that affect their heart or lungs.

For example, you may develop tachycardia, which is an abnormally fast heartbeat, or heart failure, where the heart fails to pump enough blood around your body at the right pressure.

Pregnancy complications

Pregnant women with severe anaemia have an increased risk of developing complications, particularly during and after birth.

They may also develop postnatal depression, which some women experience after having a baby.

Research suggests babies born to mothers who have untreated anaemia are more likely to:

  • be born prematurely – before the 37th week of pregnancy
  • have a low birth weight
  • have problems with iron levels themselves
  • do less well in mental ability tests

Restless legs syndrome

Some cases of restless legs syndrome are thought to be caused by iron deficiency anaemia. Doctors often refer to this as secondary restless legs syndrome.

Restless legs syndrome is a common condition that affects the nervous system, and causes an overwhelming, irresistible urge to move the legs. It also causes an unpleasant feeling in the feet, calves and thighs.

Restless legs syndrome caused by iron deficiency anaemia can usually be treated with iron supplements.

Last updated:
10 March 2023