Iron deficiency anaemia occurs when the body does not 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 is known as menorrhagia.

Pregnancy

It is 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 and others may need to increase the amount of iron in their diet (see below).

Read more about vitamins and nutrition in pregnancy.

Gastrointestinal blood loss

Your gastrointestinal tract is the part of your 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, and in women who have been through 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 outlined below.

Non-steroidal anti-inflammatory drugs (NSAIDs)

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. Do not stop taking a medicine you have been prescribed unless your GP advises you to.

Stomach ulcers

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

Stomach ulcers can cause your stomach lining to bleed, which leads to anaemia. In some cases, this blood loss can cause you to vomit blood or pass blood in your stools (faeces). 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 of the stomach or colon.

When diagnosing the cause of anaemia, your GP will check for possible signs of cancer. If your GP suspects cancer, you will 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.

Read more about stomach cancer and bowel cancer.

Angiodysplasia

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

Chronic kidney disease

Many people with chronic kidney disease (CKD) 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.

Read more information from the National Institute of Health and Care Excellence (NICE) on treating anaemia in people with chronic kidney disease.

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 inflammation (redness and swelling) 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 and 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 lot of blood 
• nosebleeds – if you have a lot of nosebleeds, this may lead to anaemia, although this is rare
• haematuria (blood in your urine) – although this rarely causes anaemia and may be a symptom of another condition

Malabsorption

Malabsorption (when your body cannot absorb iron from food) 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 your stomach (gastrectomy).

Lack of iron in your diet

Unless you are pregnant, it is rare for iron deficiency anaemia to be caused solely by a lack of iron in your diet. However, a lack of dietary iron can make you more likely to develop 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, due to the lack of meat in their diet. However, it is possible to gain enough iron in a vegetarian or vegan diet through 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

Pregnant women may have to increase the amount of iron-rich food they consume during their pregnancy to help avoid iron deficiency anaemia.

Read more about vegetarian and vegan diets and good sources of iron.

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.

Tiredness

As iron deficiency anaemia can leave you tired and lethargic (lacking in energy), you may be less productive and active at work. Your ability to stay awake and focus could decrease, and you may 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), making you more likely to become ill.

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 (an abnormally fast heartbeat) or heart failure (where your heart is not pumping blood around your body very efficiently).

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 parents 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 birthweight
• have problems with iron levels themselves
• do less well in mental ability tests

Restless legs syndrome

Some cases of restless legs syndrome (RLS) are thought to be caused by iron deficiency anaemia. Doctors may refer to this as “secondary RLS”.

RLS is a common condition affecting the nervous system, which causes an overwhelming, irresistible urge to move the legs. It also causes an unpleasant feeling in the feet, calves and thighs.

RLS caused by iron-deficiency anaemia can usually be treated with iron supplements.

If you experience symptoms of iron deficiency anaemia, see your GP. 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 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 will 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, there is not 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 due to 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.

This type of anaemia is more common in people who are over 75 years old.

Read more about vitamin B12 and folate deficiency anaemia.

Finding the cause

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

• your diet – to see what you typically eat and whether this includes any iron-rich foods
• any medicines that you take – to see if you have been regularly taking a type of medicine that can cause gastrointestinal bleeding (bleeding from the stomach and intestines), such as ibuprofen or aspirin
• your menstrual pattern – if you’re a woman, your GP may ask if you have been experiencing particularly heavy periods
• your family history – you will be asked if your immediate family has anaemia or a history of gastrointestinal bleeding or blood disorders
• blood donation – your GP may ask if you regularly donate blood
• other medical conditions – your GP may ask if you have recently had another illness or experienced other symptoms, such as weight loss

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

Physical examination

A physical examination will usually only be needed if the cause has not been found through your medical history and symptoms.

In these cases, your GP may:

• examine your abdomen (stomach) to check for any physical signs of gastrointestinal bleeding
• look for signs of heart failure (when your heart is not pumping blood around your body very efficiently), such as swollen ankles, as 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 are bleeding from your bottom. This is a common procedure that can help your GP find out if there is something in your gastrointestinal tract that is causing bleeding. Your GP will insert a gloved, lubricated finger into your bottom so they can feel any abnormalities.

A rectal examination is not something to be embarrassed about, as it is a procedure your GP will be used to doing. It should not cause great pain or discomfort, and you will only feel a slight feeling, as if your bowels are moving.

Pelvic examination

Women may have a pelvic examination if their GP suspects 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 gloved, lubricated fingers into your vagina to feel whether your uterus (womb) is tender or enlarged.

A pelvic examination will not be done without your consent, 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), who can 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 is a possibility your symptoms could be caused by stomach or colon cancer (although these are unlikely to be the cause).

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

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 will not get as much oxygen as they usually would.

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

Other forms 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

The main symptoms of iron deficiency anaemia include:

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

If you have any of these symptoms, speak to your GP, as they can diagnose iron deficiency anaemia through a simple blood test.

Read more about the symptoms of iron deficiency anaemia and 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 taking non-steroidal anti-inflammatory drugs (NSAIDs), a stomach ulcer, stomach cancer or bowel cancer.

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

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

The underlying cause will also need to be treated so that you don’t get anaemia again. You may also be advised to increase the amount of iron in your diet.

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 in the body affects your immune system (the body’s natural defence system).

Severe iron deficiency anaemia may increase your risk of developing complications that affect the heart or lungs, such as tachycardia (an abnormally fast heartbeat) or heart failure (when your heart is not pumping blood around your body very well).

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.

The Map of Medicine is used by doctors throughout the NHS to determine the best treatment options for their patients. NHS Choices offers everyone in England exclusive and free access to this cutting-edge internet resource, which lets you see exactly what your doctor sees.

The information in the Map has been approved by the UK’s leading clinical experts, is based on the best available clinical evidence, and is continually updated. To take advantage of this unique resource go to:

Map of Medicine: anaemia

Many people with iron deficiency anaemia will only have a few signs or symptoms.

The severity of these symptoms largely depends on how quickly your anaemia develops. You may only notice few symptoms 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 lethargy (lack of energy)
• shortness of breath
• heart palpitations (noticeable heartbeats)
• a pale complexion

Less common symptoms include:

• headache 
• tinnitus (hearing sounds coming from inside the body, rather than from an outside source)
• 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 (a condition known as pica)
• difficulty swallowing (dysphagia)
• painful ulcers (open sores) on the corners of your mouth
• spoon-shaped nails

When to see your GP

If you experience symptoms of iron deficiency anaemia, see your GP. They can usually diagnose the condition with a simple blood test.

Read more about diagnosing 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 two or three times a day.

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

• abdominal (tummy) pain
• constipation or diarrhoea
• heartburn
• feeling sick
• black stools (faeces)

These side effects should settle down over time, although your GP may advise taking the tablets with food or shortly after eating to help minimise side effects, if they are severe. Your GP may also recommend you only take one or two tablets a day, instead of three, if you are finding side effects difficult to cope with. 

If you cannot 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, as it contains a less concentrated dose of iron. However, it may take longer for 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.

Storing iron supplements

As with all medications, it’s important to store iron supplements out of the reach of children. This is because 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 contribute to your iron deficiency anaemia, your GP will tell you how to include more iron in your diet.

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

You should also try and include foods from all major food groups in your diet, to ensure it is healthy and well-balanced. In particular, you should try to include foods and drinks containing vitamin C, as vitamin C can help your body to absorb iron.

However, high levels 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), which are medications sometimes 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

If you are finding it difficult to include iron in your diet, you may be referred to a dietitian (a health professional who specialises in nutrition). They can 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 and, in particularly severe cases, surgery. Read more about treating heavy periods. 

Monitoring

Your GP will ask you to return for a check-up two to four weeks after you have started taking iron supplements, to check how well you have responded to the treatment. Your haemoglobin levels will be checked in a blood test.

If the result of the blood test shows an improvement, you will be asked to continue taking your 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 you continue taking iron supplements for three months to help build up the iron levels in your body.

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

Continuing treatment

In some people, after iron levels in the body have been replenished, they start to fall again.

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

If this happens, you may be prescribed an ongoing iron supplement to help stop your anaemia returning. This will usually be in tablet form, which you will have to take once a day. 

If treatment is ineffective

If your iron levels do not improve, your GP will ask how regularly you have been taking your iron supplements. Some people are put off taking the medication because of the side effects (see above). However, your condition will not improve if you don’t take the supplements.

If you have been taking the supplements as prescribed and your iron levels have still not improved, your GP may refer you to a specialist for a assessment.