What is anemia?

Anemia happens when a person’s blood is low on hemoglobin and does not have enough red blood cells. Hemoglobin is a protein that helps carry oxygen through the body. When a person develops anemia, he or she is said to be "anemic."

There are several different types of anemia. Each type is caused by one of these factors:

  • The body cannot make enough hemoglobin.
  • The body makes hemoglobin, but the hemoglobin doesn't work correctly.
  • The body does not make enough red blood cells.
  • The body breaks down red blood cells too fast.

Who is most likely to develop iron-deficiency anemia?

Anyone can develop iron-deficiency anemia, although the following groups have a higher risk:

  • Women: Blood loss during monthly periods and childbirth can lead to anemia.
  • Children, ages 1 to 2: The body needs more iron during growth spurts.
  • Infants: Infants may get less iron when they are weaned from breast milk or formula to solid food. Iron from solid food is not as easily taken up by the body.
  • People over 65: People over 65 are more likely to have iron-poor diets.
  • People on blood thinners: These include aspirin, Plavix®, Coumadin®, or heparin.

If I am pregnant, should I be concerned about anemia?

Yes. If you are pregnant, you are more likely to develop iron-deficiency anemia. Your unborn baby relies on you for iron and other nutrients. Many women who are pregnant take iron pills to prevent anemia.

To make sure that you have enough iron for you and your baby, eat well-balanced meals and follow your healthcare provider's instructions for taking vitamins and adding iron to your diet.

Are there different types of anemia?

Yes. Iron-deficiency anemia is just one type of anemia. Other types are caused by:

  • Diets lacking in vitamin B12 (the body is unable to use, or absorb Vitamin B12)
  • Diets lacking in folic acid (or, the body is unable to use folic acid)
  • Inherited blood disorders (sickle cell anemia, thalassemia)
  • Conditions that cause red blood cells to break down too fast

This chart describes some of the different types of anemia, their causes and the related blood factors:

Iron-deficiency anemia

  • Causes: Blood loss, not enough iron in the diet
  • Factors: Body cannot make enough red blood cells.

Pernicious anemia

  • Causes: Body is unable to absorb vitamin B12.
  • Factors: Body cannot make enough red blood cells.

Folic acid-deficiency anemia

  • Causes: Not enough folic acid in the diet; body is unable to use folic acid; or caused by an illness
  • Factors: Body cannot make enough red blood cells.

Hemolytic anemia

  • Causes: Inherited or acquired diseases that cause the red blood cells to be deformed; harmful substances; reaction to certain drugs
  • Factors: Body breaks down red blood cells too fast.

Sickle cell anemia

  • Causes: Inherited disease that is most common among African-Americans; red blood cells become sickle-shaped
  • Factors: Hemoglobin doesn't work right; the shape of the red blood cells causes them to clog blood vessels and break down easily.

What causes anemia?

The most common cause of anemia is low levels of iron in the body. This type of anemia is called iron-deficiency anemia. Your body needs iron to make hemoglobin; without the needed amount of iron, your body cannot make hemoglobin.

Causes of low iron in the body:

  • Bleeding, either from losing a large amount of blood quickly (for instance, in a serious accident) or losing small amounts of blood over a long period of time. The body loses more iron with blood loss than it is able to replace with food. This can happen to women having heavy menstrual periods or in people who have inflammatory bowel disease.
  • Not enough iron in the diet
  • An increase in the body's need for iron (during pregnancy)

What are the symptoms of anemia?

Several symptoms occur in all types of anemia, including:

  • Feeling tired
  • Shortness of breath
  • Dizziness
  • Headache
  • Feeling cold
  • Weakness
  • Pale skin

Last reviewed by a Cleveland Clinic medical professional on 10/25/2017.


  • National Heart, Lung, and Blood Institute. Anemia. Accessed 3/6/2018.
  • National Heart, Lung, and Blood Institute. Your Guide to Anemia. Accessed 3/6/2018.

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