What Is Anemia?

Anemia is when the level of healthy red blood cells (RBCs) in the body becomes too low. This can lead to health problems because RBCs contain hemoglobin, which carries oxygen to the body's tissues. Anemia can cause a variety of complications, including fatigue (tiredness) and stress on the body's organs.

Having fewer red blood cells than normal can happen because:

  1. The body is destroying red blood cells.
  2. Red blood cells are being lost.
  3. The body is producing red blood cells too slowly.

Anemia a fairly common blood disorder with many causes. They include inherited disorders, nutritional problems (such as an iron or vitamin deficiency), infections, some kinds of cancer, and exposure to a drug or toxin.hemoglobin illustration

Anemia From Destruction of Red Blood Cells

When the body destroys red blood cells (a process called hemolysis) more quickly than normal, the bone marrow makes up for it by increasing production of new red cells. But if red blood cells are destroyed faster than they can be replaced, a person will develop anemia. This is called hemolytic anemia.

Autoimmune hemolytic anemia happens when the body's immune system mistakenly attacks and destroys RBCs. This can happen because of disease, but sometimes no cause is found.

Inherited hemolytic anemia is due to an inherited (passed down from parents to their children) defect in the red blood cells. These defects can cause anemia. Common forms of inherited hemolytic anemia include sickle cell disease, thalassemia, glucose-6-phosphate dehydrogenase (G6PD) deficiency, and hereditary spherocytosis.

  • Sickle cell disease is a severe form of anemia that's most common in people of African heritage (about 1 out of every 500 African-American children is born with it). It affects hemoglobin, a protein in red blood cells that helps carry oxygen throughout the body. RBCs with normal hemoglobin move easily through the bloodstream because of their rounded shape and flexibility. Sickle cell disease makes RBCs sticky, stiff, and more fragile, and they form into a curved, sickle shape. Instead of moving through the bloodstream easily, sickle cells can clog blood vessels. When blood can't get where it's needed, the body's tissues and organs don't have the oxygen they need to stay healthy.

  • Thalassemia affects the way the body makes hemoglobin. The body contains more red blood cells than any other type of cell, and each has a life span of about 4 months. Each day, the body produces new RBCs to replace those that die or are lost from the body. With thalassemia, the cells are destroyed at a faster rate, leading to anemia.

    Thalassemia major, also called Cooley's anemia is a severe form of anemia where red blood cells are rapidly destroyed and iron is deposited in the vital organs. Thalassemia minor causes less severe anemia.
  • G6PD deficiency. G6PD is one of many enzymes that help the body process carbohydrates and turn them into energy. G6PD also protects RBCs from harmful byproducts that can gather when a person takes certain medicines or when the body is fighting an infection. In people with G6PD deficiency, either the red blood cells don't make enough G6PD or what's produced doesn't work correctly. Without enough G6PD to protect them, the cells can be damaged or destroyed. 

    G6PD deficiency most commonly affects males of African heritage, although it has been found in many other people.
  • Hereditary spherocytosis is an inherited condition where red blood cells aren't shaped correctly (like tiny spheres, instead of disks) and are very fragile because of a genetic problem with a protein in the structure of the red blood cell. This causes the cells to be easily destroyed and can cause anemia, jaundice (yellow-tinged skin), and enlargement of the spleen. A family history increases the risk for this disorder, which is most common in people of northern European heritage but can affect all races.

Anemia From Red Blood Cell Loss

Blood loss can cause anemia — whether from excessive bleeding due to injury, surgery, or a problem with the blood's clotting ability. Slower, long-term blood loss, such as intestinal bleeding from inflammatory bowel disease (IBD), also can cause anemia, as can heavy menstrual periods in teen girls and women. All of these factors increase the body's need for iron because iron is needed to make new red blood cells.

Anemia From Slow Production of Red Blood Cells

Aplastic anemia happens when the bone marrow can't make enough blood cells. This can be due to a viral infection, or exposure to certain toxic chemicals, radiation, or medicines (like antibiotics, anti-seizure drugs, or cancer treatments). Some childhood cancers like leukemia can cause it, while some genetic and other chronic diseases can affect how the bone marrow works.

High levels of hemoglobin and RBCs help fetal blood carry enough oxygen to developing babies in utero. After the birth, more oxygen is available and a baby's hemoglobin level normally drops to a low point at about 2 months of age. This is called physiologic anemia of infancy. This temporary and expected drop in the blood count is normal and no treatment is needed because the baby's body soon starts making RBCs on its own.

Because iron is essential to hemoglobin production, anemia can happen when someone has an iron deficiency. Poor dietary iron intake (or excessive loss of iron from the body) can lead to iron deficiency anemia. This is the most common cause of anemia in kids. It can affect kids at any age, but is most common in those younger than 2 years old. Young children who drink excessive amounts of milk are at increased risk for iron deficiency.

iron deficiency anemia illustration

Girls going through puberty also have a high risk for iron deficiency anemia because of the onset of menstruation. They should be sure to include plenty of iron in their diets because of this monthly blood loss.

What Are the Signs of Anemia?

Early symptoms of anemia include mild skin paleness and decreased pinkness of the lips and nailbeds. These changes may happen slowly, though, so they can be difficult to notice. Other common signs include:

  • irritability
  • being very tired
  • dizziness, lightheadedness, and a fast heartbeat

Anemia due to excessive destruction of red blood cells also can cause jaundice, an enlarged spleen, and dark tea-colored urine.

In infants and preschoolers, iron deficiency anemia can cause developmental delays and behavioral disturbances, like decreased motor activity and problems with social interaction and paying attention. Developmental problems may last into and beyond school age if the iron deficiency is not treated.

How Is Anemia Diagnosed?

Often, doctors diagnose anemia as the result of blood tests done as part of a routine physical examination. A complete blood count (CBC) may show that there are fewer red blood cells than normal.

Other diagnostic tests may include:

  • Blood smear examination: Blood is smeared on a glass slide for microscopic examination of red blood cells, which can sometimes indicate the cause of the anemia.
  • Iron tests: These include total serum iron and ferritin tests, which can help determine if anemia is due to iron deficiency.
  • Hemoglobin electrophoresis: This identifies any abnormal types of hemoglobin and helps diagnose sickle cell disease, thalassemia, and other inherited forms of anemia.
  • Bone marrow aspiration and biopsy: This test can help determine whether cell production is happening normally in the bone marrow. It's the only way to diagnose aplastic anemia definitively and is also used if a disease affecting the bone marrow (such as leukemia) could be causing the anemia.
  • Reticulocyte count: A measure of young red blood cells, this helps doctors see if red blood cell production is at normal levels.

Your doctor might ask you about a family history of anemia and your child's symptoms and medicines. The doctor might order other tests to look for specific diseases that could be causing the anemia.

How Is Anemia Treated?

Treatment for anemia depends on its cause. 

For iron deficiency anemia, the doctor may prescribe medicine as drops (for infants) or as a liquid or tablet (for older kids). Medicine usually must be taken for as long as 3 months to rebuild the body's store of iron. The doctor also may recommend adding certain iron-rich foods to a child's diet or reducing milk intake.

If your teenage daughter is anemic and has heavy or irregular menstrual periods, the doctor may prescribe hormonal treatment to help regulate the bleeding.

Folic acid and vitamin B12 supplements may be recommended for anemia due to a deficiency of these nutrients. However, this is rare in children.

Anemia caused by an infection will usually improve when the infection passes or is treated. If a certain medicine appears to be the cause, the doctor may discontinue it or replace it with something else (unless the benefit of the drug outweighs this side effect).

Depending on the cause, treatment for more severe or chronic forms of anemia may include:

  • transfusions of normal red blood cells taken from a donor
  • removal of the spleen or treatment with medicines to prevent blood cells from being removed from circulation or destroyed too rapidly
  • medicines to fight infection or stimulate the bone marrow to make more blood cells

In some cases of sickle cell anemia, thalassemia, and aplastic anemia, bone marrow transplantation may be used. In this procedure, bone marrow cells taken from a donor are injected into the child's vein. The bone marrow cells then travel through the bloodstream to the bone marrow and make new blood cells.

How Can I Help My Child?

The type, cause, and severity of your child's anemia will determine what kind of care is needed. Kids often tolerate anemia much better than adults.

In general, a child with significant anemia may tire more easily than other kids and need to take it easy. Make sure your child's teachers and other caregivers are aware of the anemia. If iron deficiency is the cause, follow the doctor's directions about dietary changes and taking any iron supplements.

If the spleen is enlarged, your child may not be able to play contact sports because there's a risk that the spleen could rupture or hemorrhage.

Certain forms of anemia (such as sickle cell disease) need other, more specific kinds of care and treatment.

How Can I Prevent Iron-Deficiency Anemia in My Kids?

Many kinds of anemia cannot be prevented. But you can help protect your kids from iron deficiency, the most common form of anemia. Before following any of these suggestions, though, be sure to talk them over with your doctor:

  • Limiting cow's milk. During their first 6 months, babies are usually protected against developing an iron deficiency by the stores of iron built up in their bodies before birth. But after month 6, they often don't get enough iron through breast milk alone or regular cow's milk (which contains less iron than fortified infant formula). Regular cow's milk can cause some infants to lose iron, and drinking lots of cow's milk can make a baby less interested in eating other foods that are better sources of iron.

    For these reasons, regular cow's milk is not recommended for children until they're 1 year old and eating an iron-rich diet. And they should not drink more than 24–32 ounces (709–946 ml) of milk each day. If you can't get your child to eat more iron-rich foods, speak with your doctor about giving your child an iron supplement.
  • Iron-fortified cereal and formula. These can help make sure your baby gets enough iron, especially during the transition from breast milk or formula to solid foods.
  • Well-balanced diet. Make sure your kids regularly eat foods that contain iron. Good choices include iron-fortified grains and cereals, red meat, egg yolks, leafy green vegetables, yellow vegetables and fruits, tomatoes, molasses, and raisins.

    If your child is a vegetarian, make an extra effort to ensure sufficient iron sources because iron found in meat, poultry, and fish is more easily absorbed than iron found in plant-based and iron-fortified foods.

    Also, certain food combinations can lower the amount of iron the body can absorb (for example, drinking coffee or tea or iced tea with a meal). On the other hand, vitamin C helps the body absorb iron.

If you have any questions about anemia or you think your child might have it, speak with your doctor.

Back to Articles

Related Articles

Word! Anemia

People who have anemia have fewer red blood cells than normal, which can make them feel tired because not enough oxygen is getting to their bodies' cells.

Read More

Word! Red Blood Cells

Red blood cells have the important job of carrying oxygen.

Read More


Iron is an important ingredient needed to make hemoglobin, the oxygen-carrying part of every red blood cell.

Read More

G6PD Deficiency

G6PD deficiency an inherited condition in which someone doesn't have enough of the enzyme G6PD, which protects red blood cells.

Read More

Blood Test: Ferritin (Iron)

Doctors may order a ferritin test when they suspect kids have too little or too much iron in their bodies.

Read More

Blood Test: Reticulocyte Count

This test measures the rate at which reticulocytes (immature red blood cells) are made in the bone marrow and enter the bloodstream. A reticulocyte count can provide information about a child's anemia.

Read More

Iron-Deficiency Anemia

Iron helps the body carry oxygen in the blood and plays a key role in brain and muscle function. Too little iron can lead to iron deficiency anemia. Read more here.

Read More

Blood Test: Hemoglobin Electrophoresis

A hemoglobin electrophoresis can help diagnose diseases involving abnormal hemoglobin production, and often is performed as part of newborn screening tests.

Read More

Becoming a Vegetarian

People choose vegetarianism for a variety of reasons. This article describes different types of vegetarianism and provides advice on ways for vegetarians to get all the nutrients they need.

Read More

PMS, Cramps, and Irregular Periods

Most period problems are common and normal. But some might be a sign that there's something else going on.

Read More


Find out about the mysterious, life-sustaining fluid called blood.

Read More

Blood Transfusions

About 5 million people a year get blood transfusions in the United States. This article explains why people need them and who donates the blood used.

Read More

Sickle Cell Disease

Sickle cell disease is a disease of the blood. Red blood cells are shaped like sickles, and can get stuck, especially inside smaller blood vessels.

Read More

Sickle Cell Disease

Sickle cell disease is a blood disorder that makes red blood cells change shape and cause health problems. Find out how to help your child.

Read More

Alpha Thalassemia

Alpha thalassemia is a blood disorder in which the body has a problem producing alpha globin, a component of hemoglobin, the protein in red blood cells that transports oxygen throughout the body.

Read More

Beta Thalassemia

Beta thalassemia is a blood disorder in which the body has a problem producing beta globin, a component of hemoglobin, the protein in red blood cells that transports oxygen throughout the body.

Read More

PMS, Cramps, and Irregular Periods

Get the facts on which period problems are normal and which ones might indicate something's going on.

Read More


Anemia is common in teens because they undergo rapid growth spurts, when the body needs more nutrients like iron. Learn about anemia, how to lower your risk of getting it, and how it's treated.

Read More


Here are the basics about the life-sustaining fluid called blood.

Read More

Spleen and Lymphatic System

The lymphatic system is an extensive drainage network that helps keep bodily fluid levels in balance and defends the body against infections.

Read More

Blood Test: Complete Blood Count

The complete blood count (CBC) is the most common blood test. It analyzes red blood cells, white blood cells, and platelets.

Read More

About Anemia

What does it mean when a kid has anemia? Learn about anemia, why kids get it, and how it's treated in our article for kids.

Read More

Sickle Cell Disease

Sickle cell disease is a blood disorder that makes red blood cells change shape and cause health problems. Find out more in this article for teens.

Read More

Note: All information is for educational purposes only. For specific medical advice, diagnoses, and treatment, consult your doctor. © 1995-2019 KidsHealth®. All rights reserved. Images provided by The Nemours Foundation, iStock, Getty Images, Veer, Shutterstock, and Clipart.com.

Search our entire site.