The first-line therapy for iron deficiency anemia is oral supplementation.[1] This therapy can even be effective in the demographic with the highest daily iron requirement: pregnant women; oral iron, when taken during pregnancy, was found to reduce maternal iron deficiency anemia and low birthweight (a side effect of maternal iron deficiency anemia).[2]
A common form and dose of oral iron is ferrous sulfate at 100–200 milligrams per day, though there’s no evidence to suggest any particular iron preparation is more effective than another. Lower doses of iron may be equally effective while reducing adverse effects.[1][3][4]. Some studies suggest that alternate-day dosing may be superior to consecutive-day dosing for increasing iron absorption.[1]
Common side effects of iron supplementation are constipation, abdominal discomfort, nausea, and vomiting. Other oral forms, such as ferrous fumarate, ferrous gluconate, or iron suspensions, may be tolerated better, though there is inconsistent evidence.[5][6][7][8] Enteric-coated iron supplements may reduce gastrointestinal side effects, but have lower absorption.[5]