Your health expert: Dr Amilia Alifrangis, Bupa Clinics GP
Content editor review by Julia Ebbens, Health content editor, December 2022.
Next review due September 2023.

If you have anaemia, you don’t have enough red blood cells or haemoglobin for your body’s needs. Red blood cells use haemoglobin to carry oxygen to your tissues and organs. Anaemia can cause symptoms such as tiredness, weakness, or shortness of breath.

Causes of anaemia

There are several reasons why you might have anaemia. It can be caused by something as simple as your diet or it can be a sign of an underlying health condition. There are three main ways that anaemia develops, and each of them affects the number of red blood cells you have.

Your body isn’t making enough healthy red blood cells

This could be because of iron deficiency, which is the most common form of anaemia. Iron deficiency is caused by a lack of iron. You can also fail to produce enough red blood cells if you don’t get enough vitamin B12 or folate in your diet or if you aren’t absorbing these nutrients properly. Having bone marrow problems can mean you don’t produce enough red blood cells. Conditions such as leukaemia or aplastic anaemia can affect your bone marrow.

There are many reasons why you may have a deficiency of iron, vitamin B12, or folate.

  • Pregnancy – if you’re pregnant, you’ll need more iron and folate than normal so the amount you get from your diet may no longer be enough. Speak to a doctor before taking any supplements.
  • Diet – if your diet is lacking in foods such as red meat and dark leafy green vegetables or you follow a vegan diet, you’re at greater risk of anaemia. This is because the iron is better absorbed from meat than from plant-based sources and most vegan foods don’t contain vitamin B12.
  • A condition that affects the absorption of nutrients from your bowel. Some health conditions, such as Crohn’s disease, coeliac disease or pernicious anaemia might lead to a deficiency in some nutrients.

Your body breaks down your red blood cells too quickly

Even if you do make enough red blood cells, they can sometimes be broken down too quickly by your body. This is called haemolytic anaemia. Haemolytic anaemia can be triggered by an underlying health condition or by using medicines such as penicillin and non-steroidal anti-inflammatory drugs (NSAIDs).

You’ve lost a lot of blood

You might lose a lot of blood suddenly – for example, because of an injury. Or it could occur gradually over time. The most common cause is heavy periods, but gradual blood loss can also be caused by the following reasons:

  • a condition that causes bleeding in your bowel – for example, piles or peptic ulcers
  • a stomach ulcer
  • following an operation
  • giving birth

Other causes of anaemia

Some of the less common reasons why you may become anaemic are described below.

  • Having a condition that affects your immune system – for example, infections, cancers (such as bowel cancer), and other diseases. These conditions can cause ongoing inflammation in your body, which can lead to fewer red blood cells being produced.
  • An autoimmune condition such as rheumatoid arthritis or lupus. These conditions can cause your body to destroy red blood cells.
  • A genetic disorder such as thalassaemia or sickle cell disease. These cause red blood cells to be destroyed or misshapen so they don’t work properly.
  • Chemotherapy for cancer treatment can affect your bone marrow. This may result in anaemia.
  • Chronic kidney disease can affect the production of your red blood cells and lead to anaemia.

Symptoms of anaemia

If you have anaemia that’s developed slowly over time, you may not have any symptoms at all. But you might eventually start to notice some signs of anaemia.

You may:

  • look pale
  • feel tired and weak
  • not feel able to do as much exercise as you normally would
  • feel dizzy
  • feel faint
  • feel short of breath when you exercise
  • have a thumping or unusual beating of your heart (palpitations)

You may have other symptoms too, depending on what’s causing your anaemia. For instance, your poo (faeces) may be dark and tarry-looking if you have a condition that’s causing bleeding in your bowels. You may have a sore tongue or changes in your taste if you’re deficient in iron, folate, or vitamin B12.

These symptoms can be caused by other things, but if you have any of them, contact your GP surgery for advice.

Diagnosis of anaemia

Your GP will ask about your symptoms and examine you. They may ask you questions about your diet and any medicines you’re taking, as well as any recent illnesses and your family history. Your GP may ask you to have a blood test. This will check:

  • the level of haemoglobin in your blood
  • how many blood cells you have
  • the size and shape of your blood cells
  • your GP may also check your levels of iron, vitamin B12, and folate

A blood test may be all you need if it’s obvious what’s causing your anaemia. By finding out the cause of your anaemia your doctor can help you get the right treatment. But if there isn’t an obvious cause, you may need to have further tests and scans. These can include blood tests and sometimes endoscopies.

Depending on the results of your tests, your GP may refer you to a specialist doctor such as a haematologist (a doctor who specialises in blood disorders).

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Treatment of anaemia

The treatment you need will depend on what’s causing your anaemia. If you have a health condition that may be responsible, you’ll need treatment for this. And if medicines are the cause, you may need to stop taking them and find an alternative.

Sometimes your doctor may not give you any treatment if your anaemia doesn’t cause you too many problems. But if it’s starting to have a significant impact on your quality of life, you may need treatment. Some of the main treatments for various types of anaemia are discussed below.

Nutritional supplements and diet

If you’re deficient in iron, folate, or vitamin B12, you may need to take supplements of these nutrients. Your GP may prescribe these for you. Iron and folate are usually taken as tablets, while vitamin B12 can be given as injections. You may need to continue to take supplements for several months until the levels in your blood are back to normal. Sometimes, you may need to carry on taking them for life.

Iron supplements can cause side-effects such as constipation, diarrhoea, nausea, and sickness. Talk to your pharmacist if you have any problems – you may be able to try a different type of tablet.

Your GP may also give you some advice on how to get more iron, vitamin B12 or folate in your diet. This will help to maintain your levels of these nutrients and may stop you from getting anaemia again. Here are some good dietary sources of iron, folate, and vitamin B12.


  • red meats including beef and lamb
  • dark green vegetables including spinach, cabbage, and kale
  • dried fruits such as apricots, prunes, and raisins
  • iron-fortified bread


  • poultry, pork, and shellfish
  • chickpeas and peas
  • brown rice
  • green vegetables including spinach, kale, and broccoli
  • citrus fruits such as oranges
  • fortified foods such as cereals

Vitamin B12

  • red meats, including beef and lamb
  • eggs
  • milk and other dairy products
  • fortified soy, bread, and cereal products
  • salmon and cod
  • nutritional yeast

Treatments for severe and ongoing anaemia

If you have severe anaemia or it can’t be treated with nutritional supplements, your doctor may offer you one or more of the following treatments.

  • Erythropoietin stimulating agents. These can help your bone marrow to make more red blood cells. It might be an option if you have anaemia associated with a long-term health condition such as kidney disease.
  • A blood transfusion can be a last resort if you have particularly severe symptoms. This will give you blood from a carefully selected donor into one of your veins via a drip in your arm. You might need to stay in hospital overnight after a blood transfusion.
  • Using corticosteroids or having surgery to remove your spleen (splenectomy) may be suggested by your doctor if your anaemia is caused by an autoimmune condition.
  • Immunosuppressive therapy may be offered if you have a severe type of anaemia in which your bone marrow isn’t producing enough blood cells (aplastic anaemia).
  • Stem cell transplant is sometimes recommended for people with aplastic anaemia. It involves replacing your bone marrow that isn’t working properly with stem cells from a donor. These cells can produce new, healthy bone marrow.

If you have certain types of anaemia – for example, sickle cell anaemia – your treatment will be tailored to your personal circumstances. You will be given a tailored plan to help you manage your health. Ask your doctor to explain your options.

Complications of anaemia

You may develop complications if your anaemia is severe, and you don’t get appropriate treatment. For example, anaemia can make an existing heart problem such as angina or heart failure worse.

Other complications can vary depending on the type of anaemia you have. For example, if you have iron-deficiency anaemia, one potential complication is not being able to fight off infections as well as you previously could. This is probably because of the effect that iron deficiency has on your immune system. But more research is needed to prove this.

If you have iron-deficiency anaemia when you’re pregnant, potential complications can affect your baby. For example, your baby may:

  • be born prematurely
  • be born with a small birth weight

You can prevent these effects by taking any iron supplements you’re prescribed while you’re pregnant.

Prevention of anaemia

Although you can’t prevent many types of anaemia, eating a healthy, well-balanced diet will help. This will make sure you’re getting enough iron, folate, and vitamin B12. To find out about good sources of these foods, see our treatment section. Talk to your GP or pharmacist if you follow a vegan diet because they can provide advice about which supplements you might need to take.

If you’re at risk of developing iron-deficiency anaemia, your GP may suggest you take regular iron tablets to prevent it. Some of the reasons why you may be at risk include:

  • you have heavy periods
  • your anaemia keeps coming back
  • you have a condition that affects absorption of iron, folate, or vitamin B12 from your bowel

Anaemia happens when you don’t have enough red blood cells or haemoglobin to meet your body’s needs.

If you have anaemia, the tissues and organs in your body might not get enough oxygen, and this can cause anaemia symptoms.

See our section on symptoms of anaemia for more information.

Anaemia has different causes. A common type is iron-deficiency anaemia, this is when you don’t have enough iron, vitamin B12 or folate in your diet. This can happen if you’re pregnant, vegan or you have a poor diet. It might also happen if you have Crohn’s disease or coeliac disease.

Anaemia can also be caused by conditions that affect your bone marrow or immune system.

See our section on causes of anaemia for more detail.

This depends on what’s causing the anaemia. How quickly anaemia develops can also make a difference to how much it affects you.

Vitamin-deficiency anaemias are usually easily treated with supplements and by making small changes to your diet.

Other types of anaemia can be more serious – for instance, if a medical condition is causing it. Ask your doctor how serious your anaemia is and what treatment is best for you.

By finding out what causes your anaemia, a doctor can help you to find the best treatment to cure it. Some types of anaemia may recur – for example, if they are result of nutrient deficiencies. But, by eating a balanced diet and keeping note of any new symptoms, you can help to prevent this from happening.

If you do not treat anaemia, this can lead to complications depending on what type of anaemia you have and how good your general health is. For example, if you don’t treat severe anaemia and have a pre-existing condition such as heart failure, your symptoms could get worse.

See our section on complications of anaemia for more information

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