A lack of vitamin B12 (vitamin B12 deficiency) causes the signs and symptoms of pernicious anemia. Without enough vitamin B12, your body can't make enough healthy red blood cells, which causes anemia.
Some of the signs and symptoms of pernicious anemia apply to all types of anemia. Other signs and symptoms are specific to a lack of vitamin B12.
The most common symptom of all types of anemia is fatigue (tiredness). Fatigue occurs because your body doesn’t have enough red blood cells to carry oxygen to its various parts.
A low red blood cell count also can cause shortness of breath, dizziness, headache, coldness in your hands and feet, pale or yellowish skin, and chest pain.
A lack of red blood cells also means that your heart has to work harder to move oxygen-rich blood through your body. This can lead to irregular heartbeats called arrhythmias (ah-RITH-me-ahs), heart murmur, an enlarged heart, or even heart failure.
Vitamin B12 deficiency may lead to nerve damage. This can cause tingling and numbness in your hands and feet, muscle weakness, and loss of reflexes. You also may feel unsteady, lose your balance, and have trouble walking. Vitamin B12 deficiency can cause weakened bones and may lead to hip fractures.
Severe vitamin B12 deficiency can cause neurological problems, such as confusion, dementia, depression, and memory loss.
Other symptoms of vitamin B12 deficiency involve the digestive tract. These symptoms include nausea (feeling sick to your stomach) and vomiting, heartburn, abdominal bloating and gas, constipation or diarrhea, loss of appetite, and weight loss. An enlarged liver is another symptom.
A smooth, thick, red tongue also is a sign of vitamin B12 deficiency and pernicious anemia.
Infants who have vitamin B12 deficiency may have poor reflexes or unusual movements, such as face tremors. They may have trouble feeding due to tongue and throat problems. They also may be irritable. If vitamin B12 deficiency isn't treated, these infants may have permanent growth problems.