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Anaemia is caused when you don’t have enough red blood cells (RBCs) or haemoglobin – the part of your RBCs that carries oxygen – to meet your body’s needs. Some general symptoms of anaemia include feeling tired, weak, dizzy and short of breath.

You may get anaemia because:

  • your body doesn’t have enough vitamins and minerals that it needs to make haemoglobin
  • your body makes RBCs that don’t work properly
  • your RBCs are destroyed or lost from your body - for example, when you bleed
A woman making a salad

Types of anaemia

Anaemia is caused when you don’t have enough red blood cells (RBCs) or haemoglobin – the part of your RBCs that carries oxygen – to meet your body’s needs. There are many different types of anaemia, which are all caused by different things. Some of the different types of anaemia are outlined below.

Iron deficiency anaemia

This type of anaemia is the most common and happens if your body doesn’t have enough iron. Your body needs nutrients like iron to make something called haemoglobin. Haemoglobin is a key part of your RBCs and without it, they can’t work properly. You may become deficient in iron if:

  • you lose a lot of blood
  • you’re not getting enough iron in the foods that you’re eating
  • your body is using more iron than usual - for example, if you’re pregnant

Vitamin B12 deficiency anaemia

You need vitamin B12 for many important processes inside your body. It helps to keep your nerves healthy and is used to make RBCs. If your body lacks vitamin B12, it can’t make as many RBCs as normal. The ones it does make are larger and get removed from your bloodstream quicker than usual.

Your body may lack vitamin B12 if:

  • the foods you eat don’t contain enough vitamin B12 - a common problem for vegetarians and vegans
  • your body can’t absorb the vitamin - an immune condition called pernicious anaemia can cause this

Folate deficiency anaemia

Your body uses folate to make cells (including your RBCs). If you don’t have enough folate, your body can’t make enough RBCs to meet its needs.

You may have folate deficiency anaemia if you’re not getting enough folate from the foods you eat. Brussels sprouts, asparagus and peas are all good sources of folate. Overcooking these vegetables may destroy the folate in them, so avoid this where you can. You may also be deficient in folate when you’re pregnant. This is because your body uses more folate than usual. If this happens, you’ll usually be given a folate supplement to correct this. Some medicines can also cause folate deficiency.

Anaemia of chronic diseases (ACD)

Some conditions like HIV and hepatitis C can cause ACD. If your body gets injured, for example, during surgery or after an accident, this can also cause ACD. These can result in anaemia because the inflammation they cause interferes with the iron that’s kept in your body. Fewer RBCs are made and sometimes those that are don’t last as long in your bloodstream as they should.

Anaemia of chronic kidney disease

If you have kidney damage, this can cause anaemia. This is because your kidneys make something called erythropoietin that’s needed for your body to make RBCs. If you have kidney damage, you won’t produce as much erythropoietin, and therefore RBCs.

Haemolytic anaemia

Haemolytic anaemia is a type of anaemia that happens when your RBCs are prematurely destroyed and removed from your blood. Usually, it’s because your body makes an antibody (part of your immune system that usually protects your body) that then breaks down your own RBCs.

Some people have haemolytic anaemia because they have inherited certain qualities or genes from their parents. Others may get haemolytic anaemia at a later stage and acquire it.

Aplastic anaemia

Aplastic anaemia is rare. It’s a condition that affects your bone marrow – the soft, spongy part inside your bones where your blood cells (including your RBCs) are made. If you have aplastic anaemia, you produce fewer RBCs than normal. Your other blood cells (including your white cells and platelets) are usually affected too.

For some people symptoms of aplastic anaemia are quite mild, but for others it can be a life-threatening condition. Lots of different things can cause aplastic anaemia, including some medical conditions and certain types of drugs. But most commonly, the cause of aplastic anaemia isn’t known.

Sickle cell anaemia

Sickle cell anaemia is a condition that is inherited from your parents. If you have this condition, your body makes faulty haemoglobin which causes your RBCs to form an unusual crescent shape. If you have sickle cell anaemia, your RBCs may clot under certain conditions. These blood clots then interfere with the flow of blood around your body. This is called a sickle cell or vaso-occlusive crisis.

Symptoms of anaemia

If you have anaemia, you may not have any symptoms at all. If you do have symptoms, they’ll differ depending on the type of anaemia that you have. However, there are some common symptoms of all types of anaemia which include feeling:

  • tired
  • weak
  • dizzy
  • short of breath
  • a thumping or unusual beating of your heart- called palpitations

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

Diagnosis of anaemia

Your GP will ask about your symptoms and examine you. He or she may also ask about your medical history. If your GP suspects you have anaemia, they’ll ask you to have a blood test. Your blood will be sent to the laboratory for some of the following tests.

  • A full blood count (FBC). This is to check the level of haemoglobin in your blood and how many of each of the different types of blood cell you have.
  • A check on iron, vitamin B12, and folate levels.
  • A blood film test. This involves looking at your blood under a microscope to check the size and shape of your red blood cells (RBCs). It will also assess the other cells that make up your blood.

You may need to have further tests to help identify the cause of your anaemia. Some of these investigations may need to be done at the hospital. Depending on the type of anaemia you have, your GP may refer you to a specialist.

Treatment of anaemia

To treat anaemia you have to treat the underlying cause. Your treatment will therefore differ depending on the type that you have. Outlined below are some of the different types of anaemia and how they can be treated.

Iron deficiency anaemia

If you’re iron deficient, it’s important to find out why this may be so you can get the right type of treatment. Some people have iron deficiency anaemia because they aren’t getting enough iron from the foods they eat. If this is the case, you can start to make a difference at home by eating foods rich in iron. These include:

  • dark green vegetables - for example, spinach or chard 
  • red meat
  • apricots
  • prunes
  • raisins

Your GP may also recommend that you take iron supplements. Side-effects of taking iron supplements may include constipation, heartburn, nausea, tummy (abdominal) pain or diarrhoea. If you have these side-effects contact your GP surgery for advice. You may need a lower dose or a different type of iron supplement. If this type of iron supplement isn’t working, or you can’t tolerate the effects, you may be offered treatment with iron injections.

If this isn’t the case, you may need further tests to find out what’s causing your iron deficiency so that you can get the best possible treatment.

Vitamin B12 deficiency anaemia

Finding out why you have vitamin B12 deficiency anaemia is important so you can get the right type of treatment. If you’re deficient because you have an underlying condition called pernicious anaemia, you’ll need to have vitamin B12 injections. You’ll need injections because pernicious anaemia stops you from being able to take in (absorb) vitamin B12.

If you have this type of anaemia because you’re not getting enough vitamin B12 from the foods you eat, your GP will recommend eating more vitamin B12-rich foods. Products that come from animals such as meat, fish, milk and eggs are all good sources. Others include some fortified soy products and cereals. These products have vitamin B12 and other nutrients added to them, making them ideal for vegans and vegetarians.

As well as keeping an eye on the foods you’re eating, you may also need supplements to replace the vitamin B12 in your body. If your body’s vitamin B12 levels go back to normal and your diet has improved, this treatment may be stopped. For more information on vitamin B12 deficiency anaemia and supplements, see our FAQ on Vitamin B12 injections and anaemia.

Folate deficiency anaemia

To treat folate deficiency anaemia your GP will advise you to eat foods containing lots of folate, including:

  • broccoli
  • Brussels sprouts
  • asparagus
  • peas
  • chickpeas
  • brown rice

You may also need to take folate (folic acid) supplements to help get your folate levels back to normal. Most people take an oral supplement, meaning the supplement is swallowed or ingested rather than being injected into your body. Treatment usually lasts for around four months.

If you have folate deficiency anaemia as a result of another underlying condition, you may need to explore other treatment options.

Anaemia of chronic diseases

If your anaemia is being caused by another underlying condition, it’s important that you get treatment for it to help improve your symptoms.

If your anaemia is manageable, it’s possible that you won’t need to have any treatment at all. But if your anaemia is interfering with your day-to-day life, or is a risk to your health, there are treatment options available.

  • Erythropoietin stimulating agents (ESAs). This type of treatment is used to help your bone marrow make more red blood cells (RBCs).
  • Blood transfusion.

Anaemia of chronic kidney disease

Your kidneys produce something called erythropoietin that’s needed to make RBCs. If you have kidney damage, you won’t have enough erythropoietin, and therefore RBCs, to meet your body’s needs.

To treat anaemia of chronic kidney disease you may have erythropoietic-stimulating agent (ESA) therapy to help your bone marrow make more RBCs. If ESA works for you, you may also be given iron supplements. This is because iron is used up when making RBCs and so you may become deficient in iron during ESA treatment.

You may also be treated for iron deficiency more generally as iron deficiency can contribute to anaemia of chronic kidney disease. For example, some people with chronic kidney disease have trouble using the iron that’s already stored inside their body or absorbing iron in the first place.  

Haemolytic anaemia

If you have haemolytic anaemia, the type of treatment you have will depend on what the cause is. You may need to stop taking certain drugs or get treatment for any underlying infections or conditions that could be causing your symptoms. You may also need to take folate supplements. This is because haemolytic anaemia can cause you to become folate deficient. Some people with haemolytic anaemia may also need to have a blood transfusion, but this will only happen if it’s absolutely necessary.

Aplastic anaemia

Most cases of aplastic anaemia are mild and don’t need any treatment. However, if your anaemia is severe you may need any of the following:

  • immune suppressive therapy (IST)
  • stem cell transplant
  • blood transfusion

If you’ve been diagnosed with aplastic anaemia and need treatment, talk to your doctor about your options.

Sickle cell anaemia

If you have sickle cell anaemia, treatment is based around stopping your symptoms from coming on and managing them if they do. Treatments include things like managing your pain with painkillers, taking a drug called hydroxycarbamide, blood or exchange transfusions and taking antibiotics to stop you getting infections. A bone marrow transplant can cure patients with sickle cell anaemia, but because of its complications, very careful thought will be given before you have this treatment.

To stop your symptoms from coming on, you should avoid things that can trigger them. Make sure you:

  • keep hydrated
  • don’t push yourself too much when doing exercise
  • avoid the cold
  • avoid high altitudes
  • treat infections  promptly

Causes of anaemia

Anaemia is caused because you don’t have enough red blood cells (RBCs) or haemoglobin – the part of your RBCs that carries oxygen – to meet your body’s needs. This can happen if:

  • your body lacks vitamins and minerals that are needed to make haemoglobin
  • your body makes RBCs that don’t work properly
  • your RBCs are destroyed or lost from your body - for example, when you bleed

Complications of anaemia

Complications can vary depending on the type of anaemia you have. Some general complications of anaemia may include:

  • feeling very tired
  • feeling short of breath
  • heart problems
  • increased risk of infections

Prevention of anaemia

Making sure you get enough of the right vitamins and minerals from the foods you eat, can help to prevent some types of anaemia. This includes some vitamin B12, iron and folate deficiency anaemias. Some food sources that contain lots of these vitamins and minerals are outlined in the table below.

Sources of vitamins and minerals

Vitamin or mineral Source
  • Red meats including beef and lamb
  • Green vegetables including spinach, watercress and kale
  • Dried fruits such as apricots
  • Poultry
  • Pork
  • Shellfish
  • Green vegetables including pees, Brussels sprouts and broccoli
Vitamin B12
  • Red meats including beef and lamb
  • Eggs
  • Dairy products

Where you can, make sure you get enough of these in your diet. You should also try to get enough vitamin C. Vitamin C is important as it helps your body take in iron from the food and drink you consume. Orange juice is a good source of vitamin C and convenient if you’re on the go.

Some types of anaemia can’t be prevented. One example is sickle cell anaemia. If you have sickle cell anaemia, you may be offered genetic counselling to talk about the risk of your children also having the condition.

FAQ: What will happen if I stop having my vitamin B12 injections?

Your anaemia may or may not return, but this will depend on what the cause is.

If your anaemia is caused by a lack of vitamin B12 in your diet, you’ll be advised to change your diet and to have vitamin B12 supplements. These supplements can be injected or taken as a tablet. When the levels of vitamin B12 in your body get back to normal, you may be able to stop having the supplements without your anaemia returning.

You might not be able to stop having supplements if:

  • you’re vegan or vegetarian
  • your anaemia is caused by something other than your diet

If you’re vegan or vegetarian, it’s unlikely that you’ll be able to maintain the levels of vitamin B12 in your body through your diet alone. This is because the most common sources of vitamin B12 come from animal products like meat, eggs and dairy products. If you have vitamin B12 deficiency anaemia that’s caused by an underlying condition such as pernicious anaemia, your body can’t take in (absorb) vitamin B12 from the foods you eat. To stop your anaemia from coming back, or getting worse, you may need life-long treatment with vitamin B12 injections.

If you’re thinking of stopping, talk to your doctor for advice. If your anaemia is caused by your diet, you may be able to take vitamin B12 supplement tablets instead of having injections. These tablets aren’t however suitable for vegans.

FAQ: Is anaemia a life-threatening condition?

For the majority of patients anaemia is not life-threatening, but rarely it can be. Your doctor will be able to assess which category you fall into and refer you appropriately.

Vitamin deficiency anaemias can often be treated successfully by making small changes to your diet and with other treatments like taking supplements. If treated in the right way, there’s no reason why these types of anaemia should become life-threatening.

However, if your anaemia isn’t managed properly and gets worse, this can lead to potentially life-threatening complications like heart failure. Some types of anaemia can also be caused by other severe and potentially life-threatening conditions. In this way, anaemia can then be seen as a life-threatening condition. Some iron deficiency anaemias for example can happen because you are bleeding as a result of a cancerous tumour.


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    Further information


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    • Anaemia - B12 and folate deficiency. NICE Clinical Knowledge Summaries., July 2015
    • Haematology. Oxford handbook of clinical medicine (online). Oxford Medicine Online., published January 2014
    • Folate deficiency. BMJ Best practice., reviewed January 2015
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    • Anaemia of chronic diseases. BMJ Best Practice., reviewed September 2014
    • Haemolytic anaemia. BMJ Best Practice., reviewed March 2015
    • Aplastic anaemia. PatientPlus., reviewed February 2014
    • Aplastic anaemia. BMJ Best Practice., reviewed May 2015
    • Sickle cell anaemia. BMJ Best Practice., reviewed February 2015
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    • Information of erythropoiesis-stimulating agents (ESA) epoetin alfa (marked as procrit, epogen), darbepoetin alfa (marked as aranesp). FDA., reviewed September 2015
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