Vitamin B12 Deficiency Anemia: Causes, Symptoms, and Treatment
Medically reviewed by Harsha Moole, MD, Internal Medicine. Last reviewed: October 2, 2026.
What kind of doctor treats Vitamin B12 Deficiency Anemia?
Most cases are first treated by a primary care doctor. When the cause is unclear, the anemia is severe, or treatment is not working, the patient may be referred to a hematologist, a blood disorder specialist. A direct primary care or concierge doctor can be a first stop for an evaluation and can refer you to a specialist when needed.
What is vitamin B12 deficiency anemia?
Vitamin B12 deficiency anemia is a condition in which the body has too few healthy red blood cells because it does not get or absorb enough vitamin B12, a nutrient found in meat, fish, eggs, and dairy. Without enough B12, red blood cells become large and do not work well.
When B12 levels drop too low, the body makes red blood cells that are bigger than normal and do not work properly, called megaloblastic anemia. Low B12 can also affect nerves.
Symptoms
Symptoms often come on slowly and include tiredness, weakness, shortness of breath, pale or yellow skin, dizziness, a fast heartbeat, and numbness or tingling in the hands and feet. A sore tongue, balance problems, and memory problems can also occur.
Causes and who gets it
The most common cause is poor absorption, often from pernicious anemia, in which the immune system attacks stomach cells needed to absorb B12. Other causes include stomach or intestinal surgery, acid-reducing medicines, gut conditions such as Crohn's disease, vegan diets without supplements, and older age.
How doctors diagnose it
Doctors start with a physical exam and questions about diet, medicines, and symptoms. Blood tests measure the number, size, and health of red blood cells and the B12 level itself.
Treatment
Treatment raises B12 levels back to normal, usually with shots, pills, or a nasal spray. People who cannot absorb the vitamin often need shots or high-dose pills. Many people feel better within days to weeks, though nerve symptoms can take longer.
When to see a doctor
Anyone with lasting tiredness, weakness, pale or yellow skin, numbness, or balance problems should see a doctor. Nerve symptoms can become permanent if untreated. Chest pain, severe shortness of breath, or fainting need emergency care.
How a direct primary care or concierge doctor fits in
A direct primary care doctor charges a flat monthly fee instead of billing insurance, while a concierge doctor usually charges more and often works alongside insurance. Either type can manage this condition, with longer visits for follow-up and repeat blood tests.
Common questions
Can I get enough vitamin B12 from food, or do I need supplements?
Sometimes. People who eat meat, fish, eggs, and dairy usually get enough B12 from food. Those on strict vegan diets, people with certain stomach or gut conditions, and some older adults may need supplements, but a doctor should guide this.
Is vitamin B12 deficiency anemia the same as iron deficiency anemia?
No. Iron deficiency anemia happens when the body lacks iron, while this condition comes from too little vitamin B12. Both cause tiredness, but the treatments are different, so blood tests are needed to tell them apart.
Will I need treatment for the rest of my life?
It depends on the cause. People who cannot absorb B12 from food, such as those with pernicious anemia, often need ongoing treatment for life. People whose low B12 comes from diet alone may only need pills or diet changes.
Can low vitamin B12 affect memory and mood?
Yes. Low B12 can cause memory problems, confusion, and mood changes. These often improve with treatment, though results vary from person to person.
Sources
- National Heart, Lung, and Blood Institute - Anemia - Vitamin B12-Deficiency Anemia
- NHS - Vitamin B12 or folate deficiency anaemia
Medical Disclaimer
This content is for general educational and informational purposes only and is not medical advice. It is not a substitute for professional medical advice, diagnosis, or treatment, and reading it does not create a doctor-patient relationship. Always seek the advice of your physician or another qualified health provider with any questions about a medical condition, and never disregard or delay seeking professional advice because of something you read here. If you think you may have a medical emergency, call 911 (or your local emergency number) immediately.
