What is the recommended oral iron dose for different age groups and sexes?

Recommended Oral Iron Dosing by Age and Sex

The recommended oral iron dose varies by age group, with infants and young children requiring 1-3 mg/kg/day of elemental iron, while adults typically need 200 mg of elemental iron daily divided into 2-3 doses. 1

Infants and Children

Premature/Low Birth Weight Infants

• 2-3 mg/kg/day of elemental iron for infants born <32 weeks or weighing <2000g 1
• 1-2 mg/kg/day for marginally low birth weight infants (2000-2500g) 1, 2
• Start between 2-6 weeks of age and continue at least until 6 months 1

Term Infants (0-6 months)

• Exclusively breastfed: No supplementation needed initially 1
• Formula-fed: Should receive iron-fortified formula (4-8 mg/L of iron) 3
• At 4 months: American guidelines recommend starting 1 mg/kg/day in exclusively breastfed infants 1

Infants (6-24 months)

• Highest iron requirements per kg in life: ~1 mg/kg/day (7.8-11 mg daily) 1
• For iron deficiency: 3 mg/kg/day of elemental iron 2
• High anemia prevalence areas: 10-12.5 mg daily (~1.1-1.4 mg/kg/day) 1

Children (2-5 years)

• Normal requirements: Iron needs decrease as growth rate slows 1
• With iron deficiency anemia: 3 mg/kg/day of elemental iron 2
• High anemia prevalence areas: 30-60 mg daily for 3 months 1
• Moderate anemia prevalence areas: 25-45 mg once weekly 1

Adolescents and Adults

Adolescents

• Requirements increase during rapid growth periods 1
• With iron deficiency: 200 mg elemental iron daily in 2-3 divided doses 1

Adult Women (non-pregnant)

• 200 mg elemental iron daily in 2-3 divided doses 1
• Alternative regimen: 60-120 mg elemental iron on alternate days (morning dose) may improve absorption and reduce side effects 4

Adult Men

• 200 mg elemental iron daily in 2-3 divided doses when indicated 1

Pregnant Women

• Iron requirements increase threefold in second and third trimesters 1
• Most pregnant women require supplementation to maintain adequate stores 1

Administration Guidelines

Timing and Absorption

• Best absorbed when taken without food or other medications 1
• Morning doses are preferable due to circadian hepcidin patterns 4
• Alternate-day dosing may improve absorption by allowing hepcidin levels to normalize 4
• Vitamin C enhances absorption; calcium, phytates, and polyphenols reduce it 1

Duration of Treatment

• Continue for at least 4 weeks 2
• If confirmed response (Hb increase ≥1 g/dL), continue for additional 2 months 2
• Reevaluate hemoglobin/hematocrit approximately 6 months after completing treatment 2

Common Formulations

Iron Preparation	Tablet Size (mg)	Elemental Iron (mg)
Ferrous fumarate	325	108
Ferrous sulfate	325	65
Ferrous gluconate	325	35

Monitoring and Side Effects

• Monitor response after 4 weeks of treatment 2
• Common side effects: constipation, dark stools, gastrointestinal discomfort 2
• Unabsorbed iron can cause gut irritation, inflammation, and dysbiosis 4

Cautions

• Avoid early introduction of cow's milk (before 12 months) and limit intake to <500 mL/day in toddlers 3
• Young infants (0-6 months) may be susceptible to iron excess due to developmental iron homeostasis 1
• High-dose iron supplementation in iron-replete infants may have adverse effects on growth 1