Megaloblastic anemia is a hematological disorder where certain cells of the bone marrow have arrested during the phase of nuclear maturation. These large cells are referred to as megaloblasts and can be easily seen on a blood smear. Megaloblastic anemia can be associated with diverse clinical manifestation ranging from personality changes, neurological deficits, glossitis and pancytopenia. Asides from medications, folic acid deficiency and vitamin B12 deficiency are the most common causes of this anemia. Any process that interferes with absorption of cobalamin or folate from the intestine can potentially cause the disorder.

The condition is seen globally but most common in people with restricted diets and in presence of malnutrition. It is important to note that megaloblastic anemia that occurs with either folate or cobalamin deficiency can present with almost identical signs and symptoms, but the latter is also associated with subacute combined degeneration of the spinal cord. Adults usually require at least 5-7 microgram of cobalamin and about 0.4 mg of folate per day. Common symptoms include:
Diarrhea
Nausea
Muscle weakness
Abnormal paleness of the skin
Glossitis (swollen tongue)
Loss of appetite/weight loss
Fast heartbeat
Smooth or tender tongue
Tingling in hands and feet
Numbness in extremities
Shortness of breath