Ferrous salt preparations (ferrous sulfate, ferrous gluconate, and ferrous fumarate) are equally tolerable. (Grade of recommendation: A, based on randomized controlled trial.) Controlled-release iron preparations cause less nausea and epigastric pain than conventional ferrous sulfate (grade of recommendation: A, based on randomized controlled trials), although the discontinuation rates between the 2 iron formulations were similar. Ferrous sulfate remains the standard first-line treatment of iron-deficiency anemia given its general tolerability, effectiveness, and low cost
