What is the recommended dose and frequency of ferrous sulfate (iron supplement) for adults and children with iron deficiency anemia?

Ferrous Sulfate Dosing for Iron Deficiency Anemia

For adults with iron deficiency anemia, ferrous sulfate should be administered at a dose of 50-100 mg of elemental iron once daily (equivalent to one 200 mg tablet of ferrous sulfate providing 65 mg of elemental iron), taken in the fasting state. 1

Adult Dosing

• Standard oral iron therapy for adults should provide 50-100 mg of elemental iron daily, which can be achieved with one tablet of ferrous sulfate 200 mg (containing 65 mg elemental iron) 1
• Treatment should be continued for approximately 3 months after normalization of hemoglobin levels to ensure adequate repletion of iron stores 1
• Morning dosing on an empty stomach maximizes absorption, as afternoon or evening doses may encounter higher hepcidin levels that reduce absorption 2
• Alternate-day dosing may improve fractional iron absorption compared to daily dosing, as daily doses ≥60 mg stimulate hepcidin production that can reduce absorption from subsequent doses 2, 3

Monitoring and Duration

• Hemoglobin should be monitored after 2-4 weeks of treatment to assess response 1
• Absence of hemoglobin rise of at least 10 g/L after 2 weeks strongly predicts treatment failure (sensitivity 90.1%, specificity 79.3%) 1
• After normalization of hemoglobin, continue treatment for approximately 3 months to replenish iron stores 1
• Following successful treatment, monitor blood counts periodically (every 6 months initially) to detect recurrent iron deficiency anemia 1

Pediatric Dosing

• For children with iron deficiency anemia, the recommended dose is 2-3 mg/kg/day of elemental iron 1
• Ferrous sulfate drops (125 mg/mL providing 25 mg/mL of elemental iron) can be used for pediatric administration 1
• Single daily dosing has been shown to be as effective as three-times-daily dosing in treating anemia in infants, which may improve adherence 4

Management of Side Effects

• If standard ferrous sulfate is not tolerated due to gastrointestinal side effects, consider:
  1. Reducing the dose to one tablet every other day 1
  2. Trying alternate-day dosing which may reduce side effects while maintaining efficacy 2, 3
  3. Using alternative oral iron preparations such as ferrous gluconate or ferrous fumarate 1
  4. Considering parenteral iron if oral preparations are contraindicated, ineffective, or not tolerated 1

Comparison of Oral Iron Preparations

• Ferrous sulfate tablets (200 mg) provide 65 mg of elemental iron and are the most cost-effective option 1
• Ferrous fumarate provides more elemental iron per tablet (69-106 mg depending on formulation) 1
• Ferrous gluconate provides less elemental iron (37 mg per 300 mg tablet) 1
• Modified-release preparations are generally less suitable for prescribing and more expensive 1

Common Pitfalls and Caveats

• Taking iron with food reduces absorption by up to 50%; advise patients to take iron supplements on an empty stomach 1
• Aluminum-based phosphate binders can reduce iron absorption 1
• Divided doses throughout the day do not improve total absorption and may actually reduce it due to hepcidin stimulation 2, 3
• Failure to respond to oral iron may be due to non-compliance, continued blood loss, malabsorption, or concurrent deficiencies of vitamin B12 or folate 1
• Ferrous iron is absorbed 4-10 times better than ferric iron preparations, making ferrous salts the preferred form for treatment 5