Anemia is a low level of healthy red blood cells (RBCs). RBCs carry oxygen from the lungs to the rest of the body. When red blood cells are low, the body does not get enough oxygen.

There are several specific types of anemia, including:

  • Anemia of chronic disease—happens with long term health issues
  • Aplastic anemia—bone marrow can not make enough RBCs
  • Iron-deficiency anemia—low levels of iron which is needed to make RBCs
  • Macrocytic B12 deficient anemia and pernicious anemia—low levels of a vitamin that is needed to make RBCs
  • Sickle cell anemia—RBCs have an abnormal shape and do not work well
Red Blood Cells
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The main causes of anemia are:

  • Blood loss, such as that caused by:
    • Heavy menstrual periods
    • Bleeding in the digestive tract
    • Bleeding in the urinary tract
    • Surgery
    • Trauma
    • Cancer
  • Body does not make enough RBCs due to one of the following:
    • Kidney disease
    • Cancer
    • Infection
    • Medication
    • Radiation therapy
    • Pregnancy
    • Lead intoxication
  • RBCs are destroyed at a higher rate than normal because of health issues such as:
    • Sickle cell anemia
    • Thalassemia
    • Enzyme deficiencies

Risk Factors

Anemia is more common in woman and woman who are pregnant. It is also more common in older adults who are sick and infants less than 2 years old.

Other factors that may increase the risk of anemia include:

  • Poor diet low in iron, vitamins, and minerals
  • Blood loss may be due to periods, surgery or injury
  • Chronic or serious illness
  • Chronic infections
  • Family history of inherited anemia such as sickle cell anemia and thalassemia



Anemia may cause:

  • Tiredness
  • Paleness
  • Shortness of breath
  • Lightheadedness
  • Headache
  • Coldness in the hands and feet
  • Chest pain
  • Rapid or irregular heartbeat


You will be asked about your symptoms and health history. A physical exam will be done. Blood tests will show how many RBCs there are and if they are healthy. Other tests may be needed to look for causes.



The goal of treatment is to increase healthy RBCs. The exact steps will depend on the cause. Underlying causes will be treated. Options to help increase the level of RBCs include:


Foods rich in iron, vitamin C, vitamin B12, and folate may be recommended. Vitamins or iron supplements may also be added.


Medicine may help to increase the amount of RBCs the body can make.

Blood Transfusions

Healthy blood from a donor may be needed. It will increase RBCs quickly. The effect will not last if the cause of anemia is not treated.

Bone Marrow or Stem Cell Transplant

RBCs are made in the bone marrow. Problems with the bone marrow can cause anemia. A transplant would help to grow new healthy bone marrow. This procedure carries risk. It is only done in severe cases of anemia.


A diet rich in iron and vitamins may help to prevent some types of anemia.

This content is reviewed regularly and is updated when new and relevant evidence is made available. This information is neither intended nor implied to be a substitute for professional medical advice. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with questions regarding a medical condition.

Edits to original content made by Denver Health.


Iron Disorders Institute 

National Heart, Lung, and Blood Institute 


Canadian Blood Services 

Health Canada 


Anemia—differential diagnosis. EBSCO DynaMed Plus website. Available at:  . Updated January 21, 2016. Accessed September 29, 2017.

Explore anemia. National Heart, Lung, and Blood Institute website. Available at: Updated May 18, 2012. Accessed September 29, 2017.

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