Pernicious Anemia

(Juvenile Pernicious Anemia; Congenital Pernicious Anemia)

Pronounced: Per-nish-us Ah-nee-mee-ah


Anemia is a low level of healthy red blood cells (RBC). 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.

Pernicious anemia is caused by a problem absorbing vitamin B12. This vitamin is needed to make healthy RBCs. Over time the low vitamin B12 levels will reduce the number of new RBCs. The sooner pernicious anemia is treated, the better the outcome.

Red Blood Cells
Nucleus factsheet image

Copyright © Nucleus Medical Media, Inc.


There are many possible causes of pernicious anemia. These include:

  • Inflammation of the stomach—atrophic gastritis
  • Immune system reaction to:
    • Intrinsic factor—a protein necessary for vitamin B12 absorption
    • Cells that produce both intrinsic factor and hydrochloric acid in the stomach
  • Removal of all or part of the stomach
  • Genetic defect

Risk Factors

Pernicious anemia is more common in people over 50 years old. It is also more common in those of northern European or Scandinavian descent. Other things that may increase the risk include autoimmune disorders, such as:


Symptoms may change or worsen over time and may include:

  • Sensation of pins and needles in feet or hands
  • Back and forth between constipation and diarrhea
  • Stinging sensation on the tongue, or a smooth red tongue
  • Weight loss
  • Problems between colors yellow and blue
  • Fatigue
  • Paleness
  • Loss of hunger
  • Change in taste sensational
  • Confusion
  • Depression
  • Problems with balance, especially in the dark
  • Ringing in the ears—tinnitus
  • Cracked lips
  • Fever
  • Lightheadedness when changing to standing position
  • Rapid heart rate


The doctor will ask about symptoms and past health. A physical exam will be done. A blood test will show low levels of RBCs. Other blood tests will also show low levels of proteins, vitamins, and other items needed to build RBCs. Other tests may be done to see why vitamin B12 levels are low.


The goal of treatment is to boost vitamin B12 levels. This should let your body increase the number of RBCs and ease anemia. Treatment may include:

  • Vitamin B12 which may be given as:
    • Vitamin B12 injections into a muscle—to bypass the stomach which cannot absorb the vitamin.
    • B12 supplement pills—may be taken along with to injections. May be more common for older adults to boost B12 that makes it into the body.
    • Intranasal Vitamin B12—a spray that delivers B12 into the nose. May help those that cannot tolerate injections.
  • Iron supplement pills—if there are also low levels of iron. Iron is needed to make RBCs.


There are no steps to prevent pernicious anemia.


Family Doctor—American Academy of Family Physicians

National Institutes of Health Office of Dietary Supplements


Health Canada

The College of Family Physicians of Canada


Explore pernicious anemia. National Heart, Lung, and Blood Institute website. Available at: Accessed February 7, 2020.

Pernicious anemia. EBSCO DynaMed website. Available at: Updated March 20, 2019. Accessed February 7, 2020.

Vitamin B12. National Institutes of Health Office of Dietary Supplements website. Available at: Updated July 9, 2019. Accessed February 7, 2020.

Last reviewed September 2019 by EBSCO Medical Review Board Marcin Chwistek, MD