Regardless of the presence of symptoms, all patients with iron deficiency anemia and most patients with iron deficiency without anemia should be treated. Generally the patients who have uncomplicated iron deficiency anemia are treated with oral iron due to the ease of administration. IV iron is often used when treating pregnant women and individuals with inflammatory bowel disease, gastric surgery, or chronic kidney disease, ongoing blood loss, physiologic or anatomic abnormality and intolerable gastrointestinal side effects of oral iron. True allergic reactions are exceedingly rare and vastly overestimated. Routine premedication is not needed prior to IV iron and the use of diphenhydramine should also be avoided.