How should I dose oral iron in my patient with iron deficiency?

By William Aird

Historically, doses of elemental iron as high as 100–200 mg per day across two to three divided doses were recommended. However, it is now recognized that a dose of iron will increase hepcidin levels, which will then inhibit the absorption of the next dose. Iron absorption is most efficient with intermediate doses and on alternate days, and this approach is recommended in patients with mild symptoms, or no or mild anaemia.

Up-to-Date recommendations:

  • We typically advise our patients to take their dose every other day as long as they can manage the schedule appropriately; a reasonable variation on the schedule that is easier to follow is to give the dose on Monday, Wednesday, and Friday.
  • There is no reason to give more than one dose per day.
  • The amount of iron in the every-other-day dose or the Monday-Wednesday-Friday dose is also not well established. However, there is not a reason to think higher doses improve absorption, and adverse effects are generally dose related. Thus, we typically use one tablet per dose (e.g. 325 mg ferrous sulfate). 

2021 British Society of Gastroenterology guidelines for the management of iron deficiency anaemia in adults:

Learn more here.