Version July 2025
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What is pernicious anemia? —
This is a condition that happens when a person cannot absorb vitamin B12 from food. Vitamin B12 is in foods that come from animals, including eggs, meat, poultry, and fish. Vegetarians and people who had weight loss surgery need to take extra vitamin B12, but they do not have pernicious anemia.
Pernicious anemia is a type of autoimmune disease. If you have this condition, an important protein in your body cannot work correctly. This protein is called "intrinsic factor," and your body needs it to absorb vitamin B12. In pernicious anemia, your immune system attacks the intrinsic factor protein or the cells in the stomach that make it. As a result, even if you eat foods containing vitamin B12, your body does not absorb the vitamin.
Vitamin B12 is an important vitamin for making blood cells. People with pernicious anemia might have:
●Too few red blood cells (called "anemia")
●Too few white blood cells (which fight infection)
●Too few platelets (which help the blood to clot)
Vitamin B12 is also important for the brain and nerves. People with pernicious anemia can have depression, thinking problems, numbness and tingling in their hands and feet, trouble with balance, weakness, or other nervous system problems.
These problems get worse the longer a person has the condition.
What are the symptoms of pernicious anemia? —
People with mild anemia might not have any symptoms. When anemia does cause symptoms, they can include:
●Pale skin or a pale color in the tissue that lines the inside of the eyelids – You can see this tissue (called "conjunctiva") by gently pulling down the lower eyelid. The tissue will appear pale instead of its normal, pinkish-red color.
●Feeling very tired
●Fast heartbeat
●Trouble breathing
●Headache and muscle pains
Symptoms related to a low white blood cell count might include getting infections more often than usual.
Symptoms related to a low platelet count might include bruising or bleeding.
People with pernicious anemia might also have changes in how their brain and nerves work. That's because vitamin B12 is important in helping the brain and nerves work normally. These changes might include:
●Problems with memory and confusion, which can become severe
●Mood problems, such as being cranky or grouchy
●Tingling or burning feelings on the skin
●Numbness
●Weakness in the arms or legs
●Trouble with balance
Is there a test for pernicious anemia? —
Yes. Doctors use different blood tests to check for vitamin B12 levels and the antibodies that cause pernicious anemia.
How is pernicious anemia treated? —
Treatment is with vitamin B12 supplements:
●These can be given as an injection (shot) of vitamin B12 or a pill that contains a high dose of vitamin B12. Regular multivitamins do not have enough vitamin B12 to treat pernicious anemia.
●Depending on how severe your condition is, your doctor might suggest starting with a shot every day or every other day for 1 week.
●People with pernicious anemia usually need to take extra vitamin B12 for the rest of their lives.
No matter what form of treatment you use, it is very important to keep taking vitamin B12. If you stop, your vitamin B12 level can become low again, and you can develop serious symptoms.
