Anaemia: Symptoms, Causes, Tests and Treatment
Table of Contents
Key takeaways
- Anaemia means the blood does not have enough healthy red blood cells or haemoglobin to carry oxygen around the body effectively.
- Common symptoms include tiredness, weakness, shortness of breath, palpitations, headaches, dizziness, pale skin and reduced exercise tolerance.
- In women, iron deficiency from heavy periods and pregnancy is common, but anaemia can also be caused by B12 or folate deficiency, chronic disease, bowel bleeding, inherited conditions or bone marrow problems.
- A full blood count is usually the first test, but ferritin, B12, folate, kidney, thyroid, inflammation and bleeding checks may be needed to find the cause.
- Do not self-treat persistent symptoms with supplements alone. Anaemia can sometimes be a sign of bleeding, inflammation or another condition that needs medical care.
Overview
Anaemia is a condition in which the body has too few healthy red blood cells, too little haemoglobin, or red blood cells that do not work as well as they should. Haemoglobin is the iron-rich protein inside red blood cells that carries oxygen from the lungs to the body’s tissues.
When oxygen delivery is reduced, the heart, lungs, muscles and brain may have to work harder. This is why anaemia can cause tiredness, breathlessness, palpitations, dizziness and poor concentration. Mild anaemia may be found only on a blood test, while severe or rapidly developing anaemia can be dangerous.
Anaemia is not one single disease. It is a result with many possible causes. Some forms are nutritional and respond to replacing iron, vitamin B12 or folate. Others are linked to blood loss, chronic inflammation, kidney disease, inherited red blood cell conditions, autoimmune disease, infections, medicines or bone marrow disorders.
For women, anaemia is often discussed in relation to heavy periods, pregnancy, postpartum recovery, vegetarian or vegan diets and perimenopausal bleeding changes. These are important, but they should not lead to assumptions. The cause still needs to be confirmed, especially if symptoms are new, severe, recurrent or unexplained.
Symptoms
Symptoms depend on how low the haemoglobin is, how quickly anaemia develops and what is causing it. Gradual anaemia can be easy to normalise because the body adapts over time.
Common symptoms include:
- persistent tiredness or lack of energy
- weakness or reduced stamina
- shortness of breath on exertion
- noticeable heartbeats or palpitations
- dizziness or light-headedness
- headaches
- cold hands and feet
- paler skin, gums or inner eyelids than usual
- chest discomfort, especially with exertion
- poor concentration, low mood or brain fog
Iron deficiency can also cause restless legs, hair shedding, brittle or spoon-shaped nails, a sore tongue, cracks at the mouth corners, itching, tinnitus, unusual food tastes or craving non-food items such as ice or paper. Vitamin B12 deficiency can cause pins and needles, muscle weakness, memory problems, vision changes, confusion, low mood, a sore red tongue or mouth ulcers. Neurological B12 symptoms need prompt assessment because some nerve problems can become long-lasting.
Common types of anaemia
Iron deficiency anaemia
Iron deficiency anaemia is the most common type. The bone marrow needs iron to make haemoglobin. Low iron may be caused by blood loss, pregnancy, not enough dietary iron, poor absorption or a combination of factors.
Vitamin B12 or folate deficiency anaemia
Vitamin B12 and folate help the body make healthy red blood cells. Deficiency can lead to larger red blood cells that do not function properly. B12 deficiency may be caused by pernicious anaemia, diet, gut conditions or medicines that affect absorption. Folate deficiency may be linked to diet, alcohol, pregnancy, some medicines or malabsorption.
Anaemia of inflammation or chronic disease
Long-term inflammatory conditions can interfere with red blood cell production and iron use. This can occur with chronic kidney disease, rheumatoid arthritis, inflammatory bowel disease, cancer, chronic infection and other ongoing illnesses.
Inherited and bone marrow-related anaemias
Some anaemias are inherited, such as sickle cell disease or thalassaemia. Others happen because the bone marrow is not making enough blood cells, or because red blood cells are being destroyed too quickly. These need specialist assessment.
Causes and risk factors
Anaemia can develop when the body does not make enough red blood cells, loses blood faster than it can replace it, or destroys red blood cells too quickly.
Common causes and risk factors include:
- Heavy periods: regular heavy or prolonged bleeding can gradually use up iron stores.
- Pregnancy: iron requirements rise during pregnancy, and deficiency is common if intake and stores do not meet demand.
- Bleeding from the stomach or bowel: ulcers, inflammation, piles, some medicines and, less commonly, cancers can cause blood loss.
- Dietary restriction: low intake of iron, B12 or folate can contribute, especially with vegan diets that do not include B12-fortified foods or supplements.
- Absorption problems: coeliac disease, Crohn’s disease, stomach surgery and some medicines can reduce nutrient absorption.
- Long-term conditions: kidney disease, inflammatory disease, cancer and chronic infection can affect red blood cell production.
- Medicines: some medicines may contribute to bleeding, absorption changes or bone marrow effects.
- Age and family history: older age and inherited blood conditions can increase risk.
Heavy periods should be taken seriously, especially if bleeding lasts more than seven days, requires very frequent pad or tampon changes, includes flooding or clots, or affects work, sleep or social life. Treating anaemia without addressing ongoing heavy bleeding can lead to repeated deficiency.
Diagnosis and blood tests
A full blood count is usually the first test. It measures haemoglobin, red blood cell size and other blood cells. Small red blood cells can suggest iron deficiency, while large red blood cells can suggest B12 or folate deficiency, although patterns are not always simple.
Depending on the result and symptoms, further tests may include:
- ferritin and iron studies to check iron stores and iron availability
- vitamin B12 and folate levels
- kidney, liver and thyroid function tests
- inflammation markers if chronic disease is suspected
- coeliac disease screening if malabsorption is possible
- faecal immunochemical testing or bowel investigations if gastrointestinal bleeding is possible
- pregnancy testing where relevant
- period history, pelvic assessment or ultrasound if heavy menstrual bleeding is a likely cause
Blood tests should be interpreted alongside the person’s history. A menstruating woman with heavy bleeding may still need bowel or absorption checks if symptoms, age, family history, weight loss, bowel changes or test results suggest another cause.
Treatment and management
Treatment has two parts: replacing what is missing and treating the reason it became low.
Iron deficiency
Iron deficiency anaemia is commonly treated with iron tablets. NHS guidance notes that iron tablets may be needed for around six months, with repeat blood tests to check recovery. Some people need a different dose, formulation or intravenous iron if tablets are not tolerated, not absorbed, or if anaemia is more severe. Iron should be kept away from children because overdose can be fatal.
B12 and folate deficiency
B12 deficiency is often treated with injections at first, followed by tablets or ongoing injections depending on the cause. Folate deficiency is usually treated with folic acid tablets for a set period, often around four months, unless the underlying reason means longer treatment is needed. B12 deficiency should be considered before folate-only treatment because folate can improve blood results while nerve damage from B12 deficiency continues.
Treating bleeding or underlying disease
If heavy periods are driving iron deficiency, options may include medicines to reduce bleeding, hormonal treatments or gynaecology review, depending on suitability and cause. If bleeding is from the stomach or bowel, the source needs investigation and treatment. Anaemia linked to kidney disease, inflammation, inherited conditions or bone marrow disorders may require specialist care.
Food, supplements and absorption
Diet can support treatment, but food alone may not correct established anaemia quickly enough. Iron-rich foods include meat, fortified cereals and bread, beans, lentils, peas, dark-green leafy vegetables and dried fruit. Vitamin C-rich foods such as citrus fruit, peppers, broccoli, tomatoes and strawberries can help the body absorb non-haem iron from plant foods.
Tea, coffee, dairy and high-phytate foods such as some wholegrain cereals can reduce iron absorption if taken at the same time as iron tablets or iron-rich meals. A practical approach is to separate iron tablets from tea, coffee and calcium-rich foods where possible, following GP or pharmacist advice.
Vitamin B12 is naturally found in meat, fish, eggs and dairy, and in fortified foods. People following a vegan diet usually need reliable B12-fortified foods or supplements. Folate sources include green vegetables, peas, broccoli, brussels sprouts, beans and fortified grain products.
Prevention and follow-up
Not every anaemia can be prevented, but risk can be reduced by treating heavy bleeding, managing long-term conditions, eating a varied diet, using pregnancy supplements as advised, and attending follow-up blood tests after treatment.
Follow-up matters because symptoms can improve before iron stores, B12 or folate are fully restored. Stopping treatment early may allow deficiency to return. Recurrent anaemia should trigger a review of the diagnosis, adherence, absorption, bleeding and any underlying condition.
People with heavy periods, pregnancy, postpartum recovery, inflammatory bowel disease, coeliac disease, kidney disease, bariatric surgery history, vegan diets, or previous deficiency may need more proactive monitoring. The schedule should be agreed with a clinician.
When to seek medical advice
See a GP if you think you may have anaemia, feel unusually tired or breathless, have palpitations, heavy periods, dizziness, unexplained hair shedding, restless legs, mouth ulcers, pins and needles, or have been told you cannot donate blood because of low haemoglobin.
Seek urgent medical advice if you have chest pain, fainting, severe shortness of breath, black or bloody stools, vomiting blood, sudden heavy bleeding, severe weakness, confusion, or symptoms in pregnancy that feel worrying. Use NHS 111 for urgent advice or call 999 in a life-threatening emergency.
Sources
- NHS, Iron deficiency anaemia
Relevance: UK guidance supporting symptoms, testing, iron treatment, diet advice, causes and complications of iron deficiency anaemia. - NHS, Vitamin B12 or folate deficiency anaemia
Relevance: Supports the B12 and folate sections, including symptoms, causes, treatment and neurological complications. - Mayo Clinic, Anemia: symptoms and causes (mayoclinic.org guidance page, link unavailable during validation)
Relevance: Current benchmark condition page covering anaemia definition, types, causes, risk factors, complications and prevention.
Disclaimer
Educational only. Results vary. Not a cure.