The common causes of iron deficiency anemia include insufficient iron intake due to increased iron demand, iron absorption disorder and excessive iron loss. 1. Increased iron demand and insufficient iron intake: for example, pregnant and lactating women, infants and young children, iron demand has increased, if the dietary iron intake is insufficient, it will lead to iron deficiency and cause iron deficiency anemia. 2. Iron absorption disorder: for example, after gastrectomy, long-term diarrhea, long-term chronic enteritis and other diseases, can lead to iron deficiency anemia due to iron absorption disorder. 3. Excessive iron loss: for example, gastroduodenal ulcer, excessive menstruation, long-term hemoptysis and other diseases, because of long-term chronic blood loss resulting in excessive iron loss, may cause iron deficiency anemia. Iron deficiency anemia may also be caused by other reasons, once the occurrence of iron deficiency anemia should go to the hospital in a timely manner to identify the causes and targeted treatment.