Vitamin B12 (cobalamin) deficiency is a common cause of macrocytic anemia and has been implicated in a spectrum of neuropsychiatric disorders.

  1. Symptoms of severe vitamin B12 deficiency (regardless of the cause) may include burning of the tongue, fatigue, weakness, loss of appetite, intermittent constipation and diarrhea, abdominal pain, weight loss, menstrual symptoms, psychological symptoms, and nervous system problems, such as numbness and tingling in the feet and hands.
  2. Common symptoms include: tiredness, lethargy, feeling faint, becoming easily breathless.
  3. Less common symptoms include: headaches, palpitations, altered taste, and ringing in the ears (tinnitus).
  4. You may look pale.