Can you prescribe ferrous sulfate (three times a day) for iron deficiency anemia?

Ferrous Sulfate Dosing for Iron Deficiency Anemia

Once daily ferrous sulfate (200 mg tablet containing 65 mg elemental iron) is the recommended dosing regimen for iron deficiency anemia, rather than three times daily dosing. 1

Optimal Dosing Strategy

The most recent guidelines from both the British Society of Gastroenterology (2021) and the American Gastroenterological Association (2024) recommend:

• Dosage: 50-100 mg of elemental iron once daily (equivalent to one 200 mg ferrous sulfate tablet) 1
• Timing: Taking iron in the fasting state improves absorption 1
• Duration: Continue for 3 months after hemoglobin normalizes to replenish iron stores 1

Why Once Daily Is Preferred Over TID:

1. Similar Efficacy: Research shows that once-daily dosing provides similar total iron absorption compared to multiple daily doses 1, 2

2. Hepcidin Physiology: Higher doses or multiple daily doses increase hepcidin levels, which paradoxically reduces absorption of subsequent doses by 35-45% 1, 2

3. Better Tolerability: Once-daily dosing reduces gastrointestinal side effects compared to multiple daily doses 1

4. Improved Adherence: Simpler regimens lead to better patient compliance 3

Monitoring Response

• Check hemoglobin within 4 weeks to assess initial response 1
• Expect hemoglobin to rise by approximately 2 g/dL after 3-4 weeks 1
• Failure to respond suggests poor compliance, continued blood loss, or malabsorption 1

Enhancing Iron Absorption

• Consider adding vitamin C (ascorbic acid) to enhance iron absorption 1
• Take iron on an empty stomach when possible 1
• Consider alternate-day dosing if daily dosing causes side effects 1, 2

Alternative Options for Non-Responders

If ferrous sulfate is not tolerated or ineffective:

1. Try alternate oral preparations: Ferrous fumarate, ferrous gluconate, or ferric maltol 1
2. Consider alternate-day dosing: May improve absorption and reduce side effects 1, 2
3. Switch to parenteral iron: Indicated when oral iron is contraindicated, ineffective, or not tolerated 1

Common Pitfalls to Avoid

1. Prescribing TID dosing: This increases side effects without improving efficacy 1, 2
2. Using modified-release preparations: These are less suitable for prescribing according to guidelines 1
3. Inadequate duration: Failing to continue treatment for 3 months after hemoglobin normalizes 1
4. Missing follow-up: Not monitoring response at 4 weeks to assess efficacy 1
5. Overlooking continued blood loss: Failing to investigate non-response 1

Special Considerations

For patients with inflammatory bowel disease:

• Once-daily dosing is still preferred 1
• Consider intravenous iron if there is active inflammation with compromised absorption 1

In summary, while traditional practice has often included TID dosing of ferrous sulfate, current evidence strongly supports once-daily dosing as equally effective, better tolerated, and more likely to promote adherence for treating iron deficiency anemia.