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

Ferrous Sulfate Dosing for Iron Deficiency Anemia

For treating iron deficiency anemia, the recommended dose of ferrous sulfate is 200 mg (providing approximately 65 mg of elemental iron) once daily, with a maximum of 100 mg elemental iron per day. 1

Dosing Recommendations

Standard Dosing

• Adult standard dose: 200 mg ferrous sulfate (65 mg elemental iron) once daily 1
• Maximum daily dose: No more than 100 mg of elemental iron per day 2
• Duration: Continue treatment for 3 months after hemoglobin normalizes to replenish iron stores 3

Alternative Dosing Schedules

• If gastrointestinal side effects occur, consider alternate-day dosing which may actually improve fractional iron absorption 1, 4
• For severe anemia or symptomatic patients, 200 mg ferrous sulfate daily is recommended 4

Special Populations

• Children: 3-6 mg/kg/day of elemental iron 5
• Women with menometrorrhagia: 60-120 mg elemental iron daily 3
• Pregnant women (preventive): 30 mg elemental iron daily 1
• Pregnant women (treatment): 60-120 mg elemental iron daily 1

Optimizing Absorption

• Take ferrous sulfate on an empty stomach if possible 1
• If GI side effects occur, take with a small amount of food 1
• Add vitamin C (250-500 mg) to enhance iron absorption 1
• Avoid taking with calcium supplements or antacids (separate by 1-2 hours) 2

Monitoring Response

• Check hemoglobin after 4 weeks of treatment 1
• Expect a rise of approximately 2 g/dL after 3-4 weeks 1
• Monitor hemoglobin and red cell indices at 3-month intervals for 1 year, then after a further year 1
• Target ferritin level >50 ng/mL in the absence of inflammation 1

When to Consider IV Iron Instead of Oral

Consider intravenous iron when:

• Oral iron is not tolerated due to side effects 2
• Patient is non-responsive to oral iron therapy 2
• Rapid correction of anemia is needed 1
• Patient has conditions affecting absorption (IBD, heart failure, dialysis) 4

Common Side Effects and Management

• Gastrointestinal symptoms: Nausea, constipation, dyspepsia, vomiting
• Management strategies:
  • Reduce dose or switch to alternate-day dosing 1, 4
  • Take with small amounts of food 1
  • Consider extended-release formulations which may have fewer GI side effects 3

Clinical Pearls

• Single daily dosing has similar efficacy to multiple daily doses and may improve adherence 6
• Ferrous sulfate has been shown to be more effective than iron polysaccharide complex in increasing hemoglobin levels 7
• Oral iron therapy should be continued for 3 months after normalization of hemoglobin to replenish iron stores 3
• For patients with inflammatory bowel disease, no more than 100 mg elemental iron per day is recommended to minimize GI side effects 2

Remember that the goal of treatment is to normalize hemoglobin levels and replenish iron stores to prevent recurrence of anemia, which directly impacts patient morbidity, mortality, and quality of life.