What is the recommended iron dosage and frequency?

From the Guidelines

Iron supplementation is typically recommended at a dose of 60 to 120 mg of elemental iron per day for iron deficiency anemia in pregnant women, as stated in the 2015 study by the U.S. Preventive Services Task Force 1. The recommended dosage and frequency of iron supplementation may vary depending on the individual's needs and health status.

• The usual dose prescribed in early pregnancy is 30 mg of elemental iron per day, but higher doses (60 to 100 mg of elemental iron per day) may be prescribed in populations at increased risk for iron deficiency anemia 1.
• For optimal absorption, iron should be taken on an empty stomach, ideally 1 hour before or 2 hours after meals, with vitamin C-containing foods or drinks to enhance absorption.
• Alternative formulations include ferrous gluconate or ferrous fumarate, which may cause fewer side effects in some patients.
• Treatment should continue for 3-6 months after hemoglobin normalizes to replenish iron stores.
• Iron should not be taken with calcium supplements, dairy products, coffee, tea, or antacids, as these reduce absorption.
• Monitoring hemoglobin levels after 2-4 weeks of therapy helps confirm response to treatment, as suggested by the 2020 guidelines from the American Gastroenterological Association 1. However, the most recent and highest quality study, published in 2020, suggests that a daily dose of 150–200 mg of elemental iron may be recommended, but lower dosing or every-other-day dosing may improve tolerability and absorption 1. Intravenous iron may be appropriate in selected patients, such as those with impaired absorption due to prior gastric surgery, with inflammatory bowel disease or chronic kidney disease, or in whom blood loss exceeds the ability to replete iron orally, as stated in the 2020 guidelines from the American Gastroenterological Association 1.

From the Research

Recommended Iron Dosage and Frequency

• The recommended iron dosage varies, but some studies suggest that doses of 60-120 mg elemental iron per day may be effective in treating iron deficiency and iron deficiency anemia (IDA) 2.
• A study published in 2020 found that oral iron doses ≥60 mg in iron-deficient women, and doses ≥100 mg in women with IDA, stimulate an acute increase in hepcidin that persists 24 h after the dose, but subsides by 48 h 2.
• The same study suggests that to maximize fractional iron absorption, oral doses ≥60 mg should be given on alternate days, and iron doses should not be given in the afternoon or evening after a morning dose 2.
• Another study published in 2022 compared the effectiveness of daily and every other day oral iron replacement therapy in women of reproductive age with iron-deficiency anemia, and found that both groups had significant improvements in hemoglobin, mean corpuscular volume, serum iron, total iron-binding capacity, and transferrin saturation after 2 months of treatment 3.
• A 2019 study recommends 100 mg ferrous fumarate once a day for symptom-free patients with anaemia, and 200 mg/day for patients with severe anaemia or symptoms 4.
• A randomized clinical trial published in 2019 found that once daily (65 mg elemental iron) ferrous sulphate is as effective as twice daily (130 mg elemental iron) dose regimen in prevention of anaemia in pregnancy, with fewer side effects and better compliance 5.

Iron Supplementation Schedules

• Some studies suggest that alternate-day schedules may be more effective than daily schedules in maximizing iron absorption and reducing side effects 2, 3.
• A study published in 2020 found that providing morning doses of 60-120 mg iron as a ferrous salt given with ascorbic acid on alternate days may be an optimal oral dosing regimen for women with iron-deficiency and mild IDA 2.
• A 2022 study found that every other day treatment with 2*80 mg (iron sulfate) had similar treatment effectiveness to daily treatment, and may increase patient compliance 3.