Ferrous sulfate

Studies in people

• Concern

  Stomach and gut upset³

  In people, ferrous sulfate raises the chance of stomach and gut side effects compared with placebo or iron given into a vein.

• Open question

  Iron levels in toddlers⁴

  In toddlers given baby food with ferrous sulfate, hemoglobin did not clearly change.

• Concern

  Stomach upset in pregnancy⁵

  In pregnant women, ferrous sulfate raised iron levels but caused more belly pain and constipation than lactoferrin.

• Benefit

  Iron levels in children⁷

  In schoolchildren with low iron, ferrous sulfate raised ferritin, and the rise lasted six months.

• Benefit

  Iron levels in women⁸

  In women, ferrous sulfate raised iron stores more than a lower-dose iron supplement, with no gut differences.

• Benefit

  Iron levels in pregnancy⁹

  In pregnant women with anemia, ferrous sulfate raised iron levels and lowered a marker of oxidative stress.

Animal and lab studies only

• Benefit

  Iron absorption from food¹⁰

  In lab studies, ferrous sulfate in strawberry-flavored plant-based yogurt gave more usable iron than the plain salt.

How it’s made and used

• Iron levels in the blood⁶

  In women, ferrous sulfate raised blood iron and free iron more than the other iron compounds tested.

The signal at the top counts the findings in people and in animal and lab studies. A concern in studies of people outranks animal and lab studies, and “No concerns” needs at least two findings in people. Findings whose study type is not stated are shown but not counted. This page is a reference, not medical advice. It describes what regulators and published research say. Talk to a doctor or dietitian about your own diet.