What is the recommended dose and treatment duration of ferrous sulphate (iron supplement) for a patient with iron deficiency anemia?

Ferrous Sulphate Dosing for Iron Deficiency Anemia

For iron deficiency anemia, the recommended dose is ferrous sulphate 200 mg once daily (providing 65 mg elemental iron), taken in the fasting state, and continued for 3 months after hemoglobin normalization to replenish iron stores. 1

Optimal Dosing Regimen

Once-daily dosing of 50-100 mg elemental iron (one ferrous sulphate 200 mg tablet) is the best compromise for initial treatment, based on evidence showing that higher doses stimulate hepcidin and reduce subsequent iron absorption by 35-45%. 1

Key Dosing Principles:

• Single morning dose on an empty stomach maximizes absorption, as the circadian increase in hepcidin is augmented by morning iron doses. 2

• Alternate-day dosing (200 mg every other day) may be equally effective with better tolerability than daily dosing, with significantly higher fractional iron absorption and lower gastrointestinal side effects. 1, 2

• The traditional regimen of 200 mg three times daily (195 mg elemental iron) is outdated and not supported by current evidence, as doses ≥60 mg stimulate acute hepcidin increases that persist 24 hours and reduce absorption of subsequent doses. 1, 2

Treatment Duration and Monitoring

Continue iron supplementation for approximately 3 months after hemoglobin normalization to ensure adequate repletion of marrow iron stores. 1, 3

Monitoring Schedule:

• Check hemoglobin at 4 weeks to assess response; expect a rise of at least 10 g/L after 2 weeks or 2 g/dL after 3-4 weeks. 1, 3

• Monitor hemoglobin every 4 weeks until normal range is achieved. 1

• After normalization, monitor every 3 months for 12 months, then every 6-12 months to detect recurrent iron deficiency. 1

Enhancing Absorption

Adding ascorbic acid (250-500 mg) with iron doses enhances absorption and should be considered when response is poor. 1, 3, 2

When to Consider Alternatives

Switch to parenteral iron if:

• No hemoglobin rise of at least 10 g/L after 2 weeks of daily oral therapy (90% sensitivity for predicting treatment failure). 1

• Intolerance to at least two oral iron preparations. 1, 3

• Hemoglobin <10 g/dL with symptomatic anemia. 1, 3

• Active inflammatory bowel disease or malabsorption. 1

Alternative Oral Formulations:

For patients intolerant to ferrous sulphate, consider ferric maltol 30 mg twice daily (licensed dose), which has comparable gastrointestinal side effects to placebo and normalizes hemoglobin in 63-66% of cases with moderate anemia after 12 weeks. 1

Switching between different ferrous salts (gluconate, fumarate) is not supported by evidence and unlikely to improve tolerance. 1

Special Population: IBD Patients

In inflammatory bowel disease, limit elemental iron to no more than 100 mg daily, as unabsorbed luminal iron may exacerbate disease activity and alter intestinal microbiota. 1

Common Pitfalls to Avoid

• Failing to continue therapy for 3 months after hemoglobin normalization leads to recurrence, as iron stores remain depleted despite normal hemoglobin. 1, 3

• Prescribing multiple daily doses reduces overall absorption due to hepcidin-mediated blockade from the first dose. 1, 2

• Not monitoring early response (2-4 weeks) delays identification of treatment failure from non-compliance, continued bleeding, or malabsorption. 1

• Assuming all gastrointestinal side effects are dose-related when they may indicate underlying pathology requiring investigation. 1