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Quick Facts

Iron Deficiency Anemia


The Manual's Editorial Staff

Last full review/revision Jan 2021| Content last modified Jan 2021
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What is iron deficiency anemia?

Iron deficiency is having too little iron in your body. Iron is in red blood cells.

Anemia is a low blood cell count. Specifically, you don't have enough red blood cells.

You need iron to make hemoglobin, the substance in red blood cells that carries oxygen throughout your body.

When there isn't enough iron in your body to make hemoglobin, your body makes too few red blood cells. The cells that are made are unusually small.

  • Iron deficiency anemia is the most common type of anemia

  • You may look pale and feel weak and short of breath

  • The most common cause of low iron is bleeding

  • Doctors measure your iron levels with blood tests

  • Doctors treat iron deficiency anemia with iron pills or rarely iron given through a vein (IV)

What causes iron deficiency anemia?

The most common causes of iron deficiency anemia are:

  • Bleeding

  • Increased need for iron when the body is growing

You need only a little iron in your daily diet. That's because your body re-uses the iron from old red blood cells to make new red blood cells. However, bleeding causes your body to lose iron. Bleeding is the most common cause of low iron and of iron deficiency anemia. The most common causes of bleeding vary by sex and age:

  • In younger women, heavy periods (menstrual bleeding)

  • In men and older women, bleeding from the digestive tract (stomach or intestines)

  • In older women, bleeding from the uterus

During periods of growth, such as pregnancy and early childhood, your body needs extra iron. To avoid iron deficiency during these times, you need to eat iron-rich foods, such as beef, chicken, and fish.

What are the symptoms of iron deficiency anemia?

Symptoms usually get worse little by little and include:

  • Feeling weak and tired

  • Looking pale

  • With very low iron, symptoms of pica (wanting to eat a substance that’s not food, such as ice, dirt, paint, or chalk)

How can doctors tell if I have iron deficiency anemia?

Doctors will do blood tests to check for a low number of red blood cells (anemia) and measure your iron levels.

How do doctors treat iron deficiency anemia?

Doctors will:

  • Treat any disorder that's causing bleeding

  • Make sure your diet contains enough iron-rich foods

  • Prescribe iron pills (or liquids for children)

Rarely, doctors give the iron by vein, but this usually isn't necessary.

Treating anemia with iron usually takes 3 to 6 weeks to work. However, you'll usually keep taking iron for about 6 months to replace all the lost iron.

The iron pills or liquid work best if you take them:

  • In the morning before eating

  • With orange juice or a vitamin C pill

Doctors will do blood tests to make sure you’ve gotten enough iron.

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