What is the recommended dose of ferrous gluconate (iron supplement) for treating iron deficiency anemia?

Ferrous Gluconate Dosing for Iron Deficiency Anemia

For treating iron deficiency anemia, ferrous gluconate requires 5-6 tablets daily (324 mg each, providing 190-228 mg elemental iron) to meet guideline-recommended targets, but ferrous sulfate is strongly preferred as first-line therapy due to superior cost-effectiveness and requiring only 3 tablets daily to achieve the same elemental iron dose. 1, 2

Standard Dosing Regimen

Target Elemental Iron Dose

• The recommended target is 200 mg of elemental iron daily for adults with iron deficiency anemia 1
• Each ferrous gluconate 324 mg tablet contains only 38 mg of elemental iron 3
• This requires 5-6 tablets daily to reach the 200 mg elemental iron target 1, 2
• The FDA-approved dosing is 1 tablet three to four times daily 3

Why Ferrous Gluconate Is Not Optimal First-Line

• Ferrous sulfate (325 mg) contains 65 mg elemental iron per tablet—nearly double that of ferrous gluconate—requiring only 3 tablets daily versus 5-6 for ferrous gluconate 2
• Ferrous gluconate costs approximately $5.08 per month versus $2.29 for ferrous sulfate 1
• All ionic iron salts (ferrous sulfate, ferrous fumarate, ferrous gluconate) are equally effective when equivalent elemental iron doses are given 1, 2
• The higher pill burden with ferrous gluconate may reduce compliance 2

Optimal Administration Strategy

Timing and Frequency

• Give iron on an empty stomach for optimal absorption 1
• Food reduces iron absorption by up to 50% if consumed within 2 hours before or 1 hour after the supplement 1, 2
• Alternate-day dosing (100-120 mg elemental iron every other day) may be as effective as daily dosing with better tolerability, as daily doses ≥60 mg stimulate hepcidin elevation that persists 24 hours and blocks subsequent iron absorption 4, 5
• If using alternate-day dosing with ferrous gluconate, give 3 tablets (114 mg elemental iron) every other morning 5

Enhancing Absorption

• Consider adding ascorbic acid (vitamin C) 250-500 mg twice daily to enhance iron absorption if response is poor 1, 2
• Do not crush or chew tablets 3

Duration and Monitoring

Treatment Duration

• Continue oral iron for 3 months after hemoglobin normalizes to replenish iron stores 4, 1, 2

Monitoring Schedule

• Check hemoglobin at 3-4 weeks—expect a rise of approximately 2 g/dL 1, 2
• If inadequate response after 3-4 weeks, consider switching to intravenous iron 1, 2
• Monitor hemoglobin and red cell indices every 3 months for one year after correction 1, 2
• Repeat iron status tests (ferritin, transferrin saturation) at 8-10 weeks 2

When to Switch to Intravenous Iron

Consider IV iron if:

• Intolerance to at least two different oral iron preparations 1, 2
• Non-compliance with oral therapy 1, 2
• Continued blood loss exceeding oral iron absorption capacity 1, 2
• Malabsorption conditions (celiac disease, post-bariatric surgery, inflammatory bowel disease) 4, 6
• Inadequate hemoglobin response after 3-4 weeks of appropriate oral therapy 1, 2
• Chronic inflammatory conditions (chronic kidney disease, heart failure, inflammatory bowel disease, cancer) 6

Critical Pitfalls to Avoid

• Don't assume all iron preparations contain the same elemental iron—ferrous gluconate has significantly less elemental iron per tablet (38 mg) than ferrous sulfate (65 mg) or ferrous fumarate (69 mg) 4, 1
• Don't give afternoon or evening doses after a morning dose—circadian hepcidin increases are augmented by morning iron, blocking subsequent absorption 5
• Don't continue oral iron indefinitely without monitoring—failure to respond suggests continued blood loss, malabsorption, misdiagnosis, or poor compliance 1
• Don't overlook gastrointestinal side effects—if they occur, taking iron with food improves tolerability but decreases absorption by 50% 2