9 Signs of Vitamin B12 Deficiency You Shouldn't Ignore

Signs of Vitamin B12 Deficiency You Should Never Ignore

Last Updated: August 22, 2026

Feeling unusually tired, weak, dizzy, or experiencing tingling in your hands and feet can happen for many reasons. In some cases, these symptoms may be associated with vitamin B12 deficiency.

Vitamin B12 is important for making healthy blood cells and keeping the nervous system functioning properly. When a deficiency becomes significant or lasts for a long time, it can cause anemia and neurological problems.

The important point is that these symptoms do not automatically mean you have a vitamin B12 deficiency. Many other health conditions can cause similar problems, so proper medical evaluation is important.

Foods that provide vitamin B12 including salmon, eggs, yogurt, milk, and fortified cereal

What Is Vitamin B12?

Vitamin B12, also called cobalamin, is an essential nutrient involved in normal red blood cell formation and nervous-system function.

Unlike many vitamins, B12 is naturally found mainly in animal-derived foods. However, people who avoid animal foods can obtain B12 from fortified foods and supplements.

For most adults, the recommended amount is 2.4 micrograms (mcg) per day. The recommendation is higher during pregnancy and breastfeeding.

Your body can also store B12, so deficiency may develop gradually rather than producing obvious symptoms immediately.

1. Unusual Tiredness or Weakness

Persistent fatigue is one of the symptoms that can occur with B12 deficiency.

A serious deficiency can contribute to vitamin B12-deficiency anemia, which means the body does not have enough healthy red blood cells. Because red blood cells carry oxygen throughout the body, anemia can contribute to tiredness and weakness.

However, fatigue is extremely common and has many possible causes. It should not be assumed to be caused by B12 deficiency without appropriate evaluation.

2. Dizziness or Lightheadedness

Some people with B12-deficiency anemia experience dizziness or lightheadedness.

This can occur alongside other anemia symptoms, including weakness, headaches, paleness, and shortness of breath.

If dizziness is persistent, severe, or accompanied by other concerning symptoms, speak with a healthcare professional rather than assuming that you simply need more B12.

3. Tingling or Numbness in Your Hands and Feet

One of the more important symptoms to recognize is a pins-and-needles sensation or numbness in the hands or feet.

Long-term B12 deficiency can affect the nervous system and may cause tingling, numbness, weakness, balance problems, or difficulty walking.

This is particularly important because prolonged nerve problems may not always completely disappear after treatment.

4. Balance or Walking Problems

A person with significant or prolonged B12 deficiency may develop problems with balance, coordination, or walking.

These symptoms can result from nervous-system involvement and should not simply be dismissed as a normal part of getting older.

If you suddenly develop difficulty walking, severe weakness, or a major change in balance, seek prompt medical attention because many other neurological conditions can cause these symptoms.

5. A Smooth, Red, or Painful Tongue

Vitamin B12 deficiency can cause glossitis, a condition in which the tongue becomes inflamed.

The tongue may appear unusually smooth, red, swollen, or painful. Some people may also experience mouth discomfort or changes involving taste.

A tongue that looks different can have many causes, so it is not by itself proof of B12 deficiency.

6. Shortness of Breath

Shortness of breath—particularly during physical activity—can occur when B12 deficiency contributes to anemia.

Because anemia reduces the blood's ability to carry oxygen efficiently, some people may become tired or short of breath more easily.

New or unexplained shortness of breath should be evaluated rather than automatically attributed to a vitamin deficiency.

7. Changes in Mood or Thinking

B12 deficiency can sometimes be associated with neurological and mental changes.

Possible symptoms include irritability, depression, confusion, slower thinking, memory problems, and other changes in mental function.

This does not mean that depression, memory loss, or mood changes are usually caused by B12 deficiency. These symptoms have many possible causes.

8. Vision Problems

Vision problems are a less common but recognized symptom of significant B12 deficiency.

Long-standing deficiency can affect the nervous system, including the optic nerve.

Any new or unexplained change in vision deserves medical evaluation because vision problems can have many causes that require prompt treatment.

9. Loss of Appetite or Unintentional Weight Loss

B12 deficiency can sometimes occur alongside reduced appetite or unintended weight loss.

These symptoms are nonspecific, however, and may occur with numerous digestive, metabolic, psychological, and other medical conditions.

Unexplained weight loss should therefore be discussed with a healthcare professional.

Who Is More Likely to Develop Vitamin B12 Deficiency?

B12 deficiency is not limited to people who eat poorly.

Your risk can increase if you:

  • Follow a strict vegetarian or vegan diet without reliable B12-fortified foods or supplements

  • Have pernicious anemia

  • Have celiac disease, Crohn's disease, or another condition affecting nutrient absorption

  • Have undergone certain stomach or intestinal surgeries

  • Are an older adult with reduced ability to absorb B12

  • Take certain medications, including metformin or some acid-reducing medicines, over the long term

  • Have other conditions that interfere with B12 absorption

This is why simply eating more B12-rich food may not solve the problem for everyone.

Vitamin B12 deficiency risk factors, symptoms, and food sources

How Is Vitamin B12 Deficiency Diagnosed?

Symptoms alone cannot reliably diagnose a B12 deficiency.

A healthcare professional may use blood tests to evaluate vitamin B12 levels and may order additional testing, such as a complete blood count or methylmalonic acid test, depending on the situation.

If you have persistent fatigue, numbness, balance problems, or other symptoms that could indicate a deficiency, getting evaluated is more useful than guessing.

Foods That Provide Vitamin B12

Vitamin B12 is naturally present in foods such as:

  • Fish and seafood

  • Meat and poultry

  • Eggs

  • Milk, yogurt, and other dairy products

Fortified foods, including some breakfast cereals and fortified plant-based milk alternatives, can also provide B12.

People following a vegan diet should pay particular attention to reliable fortified foods or an appropriate B12 supplement because unfortified plant foods generally do not provide a dependable natural source of B12.

Can Vitamin B12 Deficiency Be Treated?

Yes. Treatment depends on why the deficiency occurred and how severe it is.

Some people can correct a dietary deficiency with oral B12 supplementation and dietary changes. Others may need different treatment, including injections, particularly when absorption is impaired or the deficiency is severe.

Treatment can improve many symptoms, but neurological problems caused by prolonged deficiency may take longer to improve and can sometimes become permanent.

That is one reason it is important not to ignore persistent neurological symptoms.

The Bottom Line

Vitamin B12 deficiency can cause symptoms ranging from fatigue and dizziness to numbness, balance problems, tongue changes, and neurological symptoms.

But these signs are not specific to B12 deficiency. The safest approach is to discuss persistent or concerning symptoms with a healthcare professional and, when appropriate, have your B12 status evaluated.

If a deficiency is confirmed, the next step is to determine its underlying cause so that the right treatment can be chosen.

Medical / Safety Note

This article is for general educational purposes and is not a diagnosis or substitute for medical care. Do not start high-dose supplements solely because you recognize one or more symptoms in this article. If you have persistent neurological symptoms, significant weakness, unexplained weight loss, or new vision or walking problems, seek medical evaluation promptly.

Authoritative Sources

  • National Heart, Lung, and Blood Institute (NHLBI), NIH — Vitamin B12-Deficiency Anemia

  • MedlinePlus — Vitamin B12-Deficiency Anemia

  • MedlinePlus — Vitamin B12

  • MedlinePlus — Methylmalonic Acid (MMA) Test

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