Diseases & care
Understanding Anaemia: Causes, Symptoms and Treatment
Anaemia is a common condition in which the blood cannot carry enough oxygen around the body, usually because there are too few healthy red blood cells or too little of a substance called haemoglobin. Because oxygen powers everything we do, anaemia often shows up as tiredness, breathlessness and looking pale. It is not a disease in itself but a sign that something else is going on, from a simple lack of iron in the diet to heavier periods or other health conditions. Most anaemia can be treated well once the cause is found. This guide explains what anaemia is, why it happens, how it is diagnosed in the UK, and how it is treated. It names no medicine doses.
Education and reference only. This article explains how treatments work in plain language — it contains no doses and is not a substitute for advice from your doctor or pharmacist. Always discuss your own treatment with a qualified clinician.
What anaemia is
Blood contains red blood cells, which carry oxygen from the lungs to every part of the body. Inside these cells is haemoglobin, an iron-rich protein that grabs onto oxygen and gives blood its red colour. Anaemia means there is not enough working haemoglobin to carry the oxygen the body needs, either because there are too few red cells or because each cell carries too little haemoglobin. Without enough oxygen reaching the tissues, the body has to work harder, which is why people feel tired and breathless. Anaemia ranges from mild, causing few symptoms, to severe. It is best thought of as a clue that prompts doctors to ask why the blood is short of healthy red cells.
Common causes
There are many causes of anaemia, and finding the right one matters because treatment depends on it. The most common worldwide is iron deficiency, when the body lacks the iron needed to make haemoglobin; this can result from not enough iron in the diet, or from blood loss, such as heavy periods or slow bleeding in the gut. Shortages of vitamin B12 or folate, other building blocks for red cells, are another common cause. Anaemia can also arise from long-term illnesses, kidney disease, problems in the bone marrow where blood is made, or inherited conditions such as sickle cell disease and thalassaemia. Because causes differ so widely, anaemia always deserves proper investigation rather than guesswork.
Recognising the symptoms
The symptoms of anaemia come from the body being short of oxygen, and they often develop gradually, so people may not notice at first. Common signs include persistent tiredness and lack of energy, feeling breathless, especially on exertion, looking pale, and having heart palpitations. Some people get headaches, feel dizzy, or notice their hands and feet feel cold. With iron deficiency specifically, some develop brittle nails, a sore tongue, or unusual cravings for non-food items such as ice. Because tiredness has so many causes, anaemia can be easy to overlook. If you feel persistently exhausted, breathless or pale without an obvious reason, it is worth seeing your GP, who can check with a simple blood test.
How anaemia is diagnosed
Anaemia is usually confirmed with a simple blood test called a full blood count, which measures the amount of haemoglobin and looks at the size and number of red blood cells. The size of the cells gives useful clues: small, pale cells often point to iron deficiency, while large cells may suggest a lack of vitamin B12 or folate. From there, your GP works out the underlying cause with further tests, perhaps checking iron, B12 and folate levels, kidney function, or looking for a source of bleeding. Finding the cause is essential, because treating the anaemia without addressing why it happened can allow a serious problem, such as bleeding in the gut, to be missed. Diagnosis is therefore about both the anaemia and its root.
Treatment and prevention
Treatment depends entirely on the cause. Iron-deficiency anaemia is often treated with iron supplements and by tackling the source, such as managing heavy periods or investigating gut bleeding, alongside eating iron-rich foods like red meat, beans, lentils and leafy greens. B12 or folate deficiency is corrected by replacing the missing vitamin, sometimes with injections. Anaemia from other conditions is treated by managing the underlying illness. In severe cases, a blood transfusion may be needed. For prevention, a balanced diet containing enough iron, B12 and folate helps, and people at higher risk, such as those with heavy periods or certain diets, should be alert to symptoms. With the right treatment, most people with anaemia recover well and regain their energy.
In short
Key takeaways
- Anaemia means the blood cannot carry enough oxygen, usually from too few red blood cells or too little haemoglobin.
- It is a sign, not a disease itself; common causes include iron deficiency, heavy periods and shortages of vitamin B12 or folate.
- Typical symptoms are persistent tiredness, breathlessness, pale skin and palpitations, often developing gradually.
- A simple full blood count confirms anaemia, and further tests find the underlying cause, which must be identified.
- Treatment depends on the cause, from iron or vitamin replacement to treating an underlying illness, and most people recover well.
Answers
Frequently asked questions
Is anaemia always caused by a lack of iron?
No. Iron deficiency is the most common cause, but it is far from the only one. Anaemia can result from shortages of vitamin B12 or folate, long-term illnesses, kidney disease, problems in the bone marrow, or inherited conditions such as sickle cell disease and thalassaemia. This is why taking iron supplements without knowing the cause is not a good idea; it may not help and could delay finding the real problem. If you think you are anaemic, see your GP for a blood test so the true cause can be identified and treated properly rather than assumed.
Can I treat anaemia by changing my diet?
Diet plays an important part, especially for iron, B12 and folate deficiency, and eating more iron-rich foods such as red meat, beans, lentils and leafy greens can help. Vitamin C, from fruit and vegetables, aids iron absorption. However, diet alone is often not enough, particularly if the anaemia is more than mild or caused by ongoing blood loss or another condition. Many people need supplements or treatment of an underlying cause as well. Rather than trying to fix it yourself, see your GP, who can confirm the type of anaemia and advise the right combination of diet, supplements and other treatment.
When should I see a doctor about tiredness?
Tiredness is very common and often not serious, but see your GP if it is persistent, unexplained, or comes with other symptoms such as breathlessness, looking pale, dizziness or palpitations, which can suggest anaemia. Also seek advice if tiredness is affecting your daily life, or if you have heavy periods, changes in your bowel habits, or blood loss you cannot explain. A simple blood test can quickly show whether anaemia is the cause. Getting checked is worthwhile, because anaemia is usually very treatable, and finding its cause can occasionally reveal another problem that needs attention.
Go deeper
Related guides
Sources
Where this is drawn from
- NICE Clinical Knowledge Summaries, Anaemia iron deficiency
- NHS, Iron deficiency anaemia: symptoms, causes and treatment
- British Society for Haematology, Guidelines on the investigation and management of anaemia
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