If Hb levels are less than 10 grams per deciliter, side effects of oral supplementation are not tolerable (e.g., constipation), and/or Hb fails to rise from treatment sufficiently, intravenous iron is often prescribed. While less convenient, it can increase Hb more quickly and with less adverse reactions, which tend to include local pain, skin irritation, and allergic reactions.[1][2]
When should iron be given intravenously?
Written by:
Fact-checked
by:
•Last Updated: May 16, 2025
Intravenous iron should be administered if hemoglobin levels are below 10 grams per deciliter, if oral iron supplementation causes intolerable side effects, or if hemoglobin does not adequately increase from treatment. Although it is less convenient, intravenous iron can raise hemoglobin levels more rapidly and with fewer adverse reactions, which may include local pain and allergic reactions.