Vitamin B12 deficiency can cause significant disease, including severe neurologic problems. However, patient presentations can vary greatly.

Signs and symptoms can include:

• Constitutional symptoms: fatigue, lack of energy, lightheadedness, loss of appetite
• Gastrointestinal problems: diarrhea or constipation
• Cardiovascular: shortness of breath, dyspnea on exertion, tachycardia, CHF
• Oral lesions: swollen, red tongue (glossitis) or bleeding gums
• Problems concentrating

Prolonged B12 deficiency can lead to significant neurologic complications, frequently related to the spinal cord, and can include:

• Mild impairment to dementia
• Depression, psychosis
• Loss of balance, limb weakness, ataxia
• Peripheral neuropathy (numbness and tingling of hands and feet)