What are the symptoms of vitamin B12 deficiency?

Typical symptoms of vitamin B12 deficiency, also known as vitamin B12 deficiency anemia, include tiredness, lack of energy, light-headedness when standing up or exercising, diarrhea, constipation, appetite loss, weight loss, pale skin, swollen or red tongue, bleeding gums, difficulty concentrating and shortness of breath.
If you’ve been deficient in vitamin B12 for a long time, you may have nerve damage. Symptoms of vitamin B12–induced nerve damage include tingling or numbness in hands and feet, balance problems, depression, confusion, irritability and, in severe cases, dementia.
Kate Geagan
Nutrition & Dietetics

Symptoms of vitamin B12 deficiency include:

  • overall lack of energy
  • unusual mood changes
  • difficulty concentrating or remembering things
  • tingling or numbness in hands or feet
  • inflamed, red, cracked tongue

    Jill A. Grimes, MD
    Family Medicine

    There may be no symptoms of B12 deficiency. In severe cases, you may develop anemia. Often, there are nonspecific symptoms such as brittle fingernails, fatigue, and forgetfulness.

    If you have a family history of true B12 deficiency, that is also a risk factor.

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    Important: This content reflects information from various individuals and organizations and may offer alternative or opposing points of view. It should not be used for medical advice, diagnosis or treatment. As always, you should consult with your healthcare provider about your specific health needs.