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Quick Facts

Overview of Anemia


The Manual's Editorial Staff

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

Anemia is not having enough red blood cells or hemoglobin. Red blood cells carry oxygen from your lungs to all of your other organs. Hemoglobin is the substance inside your red blood cells that actually carries the oxygen.

  • When you have too few red blood cells or too little hemoglobin, your blood can’t carry all the oxygen your body needs

  • Anemia causes tiredness and weakness

  • There are many causes of anemia

  • It's important to test for anemia as you get older because it can shorten your life span

What causes anemia?

Causes of anemia include:

  • Losing a lot of blood because of an injury, heavy menstrual periods, or digestive or urinary tract problems (chronic bleeding)

  • Not making enough red blood cells because your body lacks enough iron, vitamin B12, or folate, or because you have leukemia or another cancer

  • Your body destroying too many red blood cells

What are the symptoms of anemia?

Symptoms depend on how severe your anemia is.

Mild anemia causes:

  • Feeling weak and tired

  • Paleness

Severe anemia causes:

  • Feeling faint and dizzy

  • Feeling thirsty

  • Sweating

  • Weak, fast pulse

  • Lower leg cramps during exercise

  • Shortness of breath

  • Chest pain

How do doctors tell if I have anemia?

Doctors do a blood test to measure your levels of hemoglobin and red blood cells. They may do other tests to find the cause of your anemia.

How do doctors treat anemia?

If a health problem is causing your anemia, doctors treat that health problem. Treatment depends on the type of anemia you have. Doctors may treat anemia with:

  • Iron supplements, taken as pills or by IV (directly into your vein)

  • Other supplements, such as vitamin B12 or folate

  • Transfusion of red blood cells, for severe anemia

  • Medicine that causes your body to make more red blood cells

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