IRON (AHY ern) replaces iron that is essential to healthy red blood cells. Iron is used to treat iron deficiency anemia. Anemia may cause problems like tiredness, shortness of breath, or slowed growth in children. Only take iron if your doctor has told you to. Do not treat yourself with iron if you are feeling tired. Most healthy people get enough iron in their diets, particularly if they eat cereals, meat, poultry, and fish.