Iron deficiency (ID) is a status in which iron amount in the body is less than the amount required to maintain normal physiologic functions. It is a result of inadequate iron absorption or a consequence of prolonged negative iron balance, both can lead to decreased iron stores as measured by serum ferritin (SF) concentrations or iron content in bone marrow. The main characters of IDA are the symptoms of lethargy, dizziness, and weakness and the signs of pallor in the skin or mucous membranes. Nothing of these manifestations is specific or sensitive. Because ID tends to develop slowly, adaptation occurs and the disease frequently goes undetected for some time. However, in severe cases, dyspnea can occur. Diagnosis of ID is difficult, and the combination of several iron status indicators seems to provide the best assessment of iron sufficiency. Low levels of serum iron, serum ferritin and transferrin saturation are a direct combination for diagnosis of ID. However, the same diagnosis can become a challenge if other inflammatory diseases are present. While oral iron is safe, affordable, and easy to administer, patients often suffer from intolerable gastrointestinal side effects. The WHO recommends that children with iron deficiency anemia be given 6 mg/kg/d elemental iron (ferrous fumarate or sulfate), orally as a single dose or divided into 2 or 3 doses, for 2 months. Therapy with iron supplements has some gastrointestinal side effects, such as abdominal discomfort, nausea, vomiting, constipation, and dark colored stools. Enteric-coated and delayed-release iron supplements are made to increase compliance, as they cause less side effects; however, they are not as well absorbed as the non-enteric-coated preparations.