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Written by Ada’s Medical Knowledge Team

Updated on

What is anemia?

Anemia is the general name for a condition where the body either cannot make enough healthy red blood cells and/or has too little hemoglobin, the substance that enables red blood cells to transport oxygen around the body. 1

There are many different types of anemia. These include, but are not limited to: 2 3 4 5

  • Iron deficiency anemia, the most common type of anemia
  • Megaloblastic anemia, often caused by a vitamin B12 deficiency or folic acid deficiency
  • Aplastic anemia, caused by damage or dysfunction in bone marrow cells
  • Hemolytic anemia, caused by red blood cells being destroyed at an increased rate

Medically speaking, anemia is broadly classified as macrocytic, microcytic or normocytic, depending on the size and volume of the red blood cells (erythrocytes): 6 7

  • Macrocytic anemia. In this category of anemia, the red blood cells are larger than normal. This includes anemia caused by vitamin B12 deficiency or folate deficiency.
  • Microcytic anemia. In this category of anemia, the red blood cells are smaller than normal. This includes anemia caused by iron deficiency, thalassemia or sickle cell disease.
  • Normocytic anemia. In this category of anemia, the red blood cells are normal in size, but fewer than normal in number. This includes anemia caused by chronic conditions, e.g. kidney disease.

Regardless of the type or cause, common symptoms of anemia include: 8

  • Tiredness and lethargy
  • Breathlessness
  • Faintness
  • Headaches

There may also be other symptoms specific to the type of anemia being experienced.

The treatment recommended for anemia depends on the underlying cause. In cases of iron or vitamin deficiency, treatment will typically involve dietary changes and sometimes the use of supplements or medications. In less common types of anemia, as well as severe cases, more complex approaches, such as blood transfusions, may be needed. 9 10 11

Find out more about how vitamin deficiency tests work.

The outlook depends on the type, cause and severity of anemia, as well as the age and overall health of the person; but with appropriate and timely treatment, recovery or effective management can be expected in many cases. 12

If left untreated, anemia can lead to complications, including reduced ability to function, lower quality of life, lung problems and even heart failure. 13 12 It is important to consult a medical practitioner without delay, should the condition be suspected.

Types of anemia

There are a number of different types of anemia. These include the following:

Iron deficiency anemia

Iron deficiency anemia is caused by a lack of iron in the body, leading to reduced levels of sufficiently functioning red blood cells. Iron deficiency can be caused by a variety of factors and conditions, including internal bleeding, pregnancy, heavy menstruation, inflammatory bowel disease (IBD) and a lack of iron in one’s diet. 9

Megaloblastic anemia

Megaloblastic anemia is a type of macrocytic anemia that can be caused by a lack of vitamin B12 or lack of folic acid (folate). This is most often due to a dietary deficiency or malabsorption, e.g. as in pernicious anemia, where the body cannot absorb sufficient amounts of vitamin B12. 3

Aplastic anemia

Aplastic anemia is a consequence of damage or dysfunction in the bone marrow cells, causing them to produce fewer red blood cells than needed. This may be the result of a number of conditions, including infectious diseases and autoimmune disorders, as well as certain substances and cancer treatments. Rarely, aplastic anemia may run in families. Examples of hereditary conditions that can lead to aplastic anemia include Fanconi anemia and Diamond-Blackfan anemia. 4

Hemolytic anemia

Hemolytic anemia occurs as a result of red blood cells being destroyed more quickly than usual. This can be caused by a number of different conditions, some of which may run in families. There are many types of hemolytic anemia. Two examples include thalassemia and sickle cell anemia, both of which are hereditary. 5


Thalassemia is a genetic disorder that affects the production and function of hemoglobin, causing red blood cells to break down more easily than normal. The condition may be mild or severe. 14

Read more about Thalassemia »

Sickle cell anemia

This is a common, severe, form of sickle cell disease – a group of conditions that cause hemoglobin to be abnormally shaped and red blood cells to break down more easily than normal. Sickle cell disease is acquired genetically. 15 16

Read more about Sickle Cell Disease »

Anemia symptoms

Common symptoms of anemia, regardless of the cause, include: 8

  • Fatigue (tiredness)
  • Lethargy (lack of energy)
  • Breathlessness
  • Faintness
  • Headaches

Less common symptoms of anemia may include: 1 17

  • Paleness
  • Palpitations (the feeling that the heart is skipping a beat or pounding)
  • Tinnitus (ringing in the ears)
  • Muscle cramps
  • Loss of appetite
  • Altered sense of taste

There may also be other symptoms, depending on the type of anemia. For example, iron deficiency anemia may cause wounds to heal slowly and brittle nails. Vitamin B12 deficiency anemia may cause pins and needles, confusion, and depression.

Good to know: In the early stages of anemia, some people may not experience symptoms. 18

People experiencing possible symptoms of anemia can use the free Ada app to carry out a symptom assessment.

Anemia causes

There are many possible causes of anemia. These include: 9 19

  • Dietary deficiencies of essential vitamins and minerals, such as vitamin B12, folic acid and iron
  • Malabsorption of nutrients, e.g. in celiac disease, Crohn’s disease
  • Substantial blood loss, e.g. from heavy menstruation or inflammatory bowel disease
  • Bone marrow problems and leukemia
  • Certain chronic conditions, e.g. rheumatoid arthritis, kidney disease (anemia of chronic disease)
  • Certain genetic disorders, e.g. thalassemia and sickle cell disease
  • Certain infections, e.g. malaria
  • Certain medications and therapies, e.g. some types of painkillers, antibiotics, drugs for hyperthyroidism 17 and cancer treatments 18
  • Periods where the body needs more energy than usual, such as puberty and pregnancy

Diagnosis of anemia

As the first step, a doctor will typically take the person’s medical history and perform a physical examination. They may then order blood tests to check: 19 18

  • Hemoglobin levels and red blood cell size (complete blood count)
  • Vitamin B12 and folic acid levels
  • Kidney function

The doctor may also ask for the following tests to be done: 19 18

  • Urine tests
  • Stool (feces) tests
  • A bone marrow biopsy, removing a small sample for examination
  • A gastroscopy or colonoscopy to examine the digestive tract

As effective treatment of anemia depends on identifying the cause, the doctor will attempt to establish what this is. Further tests may be required if the cause is not clear.

Anemia treatment

The treatment recommended will depend on the underlying cause, as well as the severity of the anemia. Treatment may include: 19 18

  • Dietary changes to include more iron or vitamin-rich foods
  • Vitamin or iron supplements
  • Antibiotics, in the case of certain infections
  • Hormonal medication, in some cases of heavy menstruation 20
  • Adjusting any medications or therapies that may be causing anemia

In severe or persistent cases of anemia, the following may be recommended: 19 18 21

  • Medication to stimulate the production of red blood cells or to slow down their destruction
  • Medication to suppress the immune system, where this is involved 17
  • Blood transfusions
  • Bone marrow transplants
  • Surgery to stop internal bleeding
  • Surgery to remove the spleen, where it is rapidly destroying red blood cells

Complications of anemia

If severe or left untreated, anemia can cause a number of complications, including the following: 22

  • Lasting fatigue leads to diminished productivity
  • Weakened immune system
  • Fast or irregular heartbeat
  • Heart failure
  • Problems during pregnancy, including fatigue, premature labor, and problems with fetal development 23
  • Increased risk of postpartum depression

Good to know: Specific types of anemia may cause other serious complications. If any kind of anemia is suspected, it is very important to consult a medical practitioner without delay.

Prevention of anemia

While it may not be possible to prevent all types of anemia, steps can be taken to reduce the risk of developing anemia related to nutritional deficiencies. These include: 19 21

  • Eating a well-balanced diet
  • Eating fortified foods and/or taking vitamin and mineral supplements where one’s diet is restrictive, e.g. vegetarians and vegans
  • Avoiding regular consumption of tannin-containing tea or coffee with meatless meals, as this may interfere with absorption of iron from plant sources 24

People experiencing symptoms that may be linked to anemia or a related condition can use the Ada app to carry out a free symptom assessment.

Other names for anemia

  • Anaemia (UK spelling)
  • Lack of blood
  • Tired blood
  • Iron deficiency

Anemia FAQs

Q: Is anemia during pregnancy common?
A: Yes. Mild anemia is quite common during pregnancy, as a pregnant person needs more iron than usual. 19 It is recommended that a pregnant person eat foods that are rich in iron, such as dark green leafy vegetables, fortified cereals, eggs, nuts, and lean meats to help prevent iron deficiency. A doctor may also recommend a vitamin and mineral supplement. They may order blood tests to check the person’s iron levels during pregnancy. If any symptoms of anemia are present, a pregnant person should consult a doctor without delay. 25

For more information about achieving a balanced diet during pregnancy, see these resources on foods to eat during pregnancy and foods to avoid during pregnancy.

Q: What are the best foods for anemia?
A: It depends on the type of anemia and what is causing it. In the case of iron deficiency anemia, iron-rich foods such as dark green leafy vegetables, fortified cereals, eggs, nuts and lean meats may be recommended to help treat the condition. 19 In the case of anemia caused by a deficiency of vitamin B12 or folic acid, other types of food may be recommended. In many cases, a well-balanced diet should provide sufficient nutrients to prevent anemia. If anemia is suspected, it is important to consult a medical practitioner, as self-diagnosis may be inaccurate.