Ferrous sulfate dosage guidelines
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Ferrous Sulfate Dosage Guidelines: Key Recommendations
Standard Dosage for Iron Deficiency and Anemia
The most common recommended dose of ferrous sulfate for adults is 60–65 mg of elemental iron per day, which is typically provided by a 325 mg ferrous sulfate tablet. This dosage is widely used for the prevention and treatment of iron deficiency anemia in various populations, including pregnant women and adults with low iron stores 234567.
Dosing Frequency: Once Daily vs. Multiple Doses
Research shows that once-daily dosing of 60–65 mg elemental iron is as effective as twice-daily or three-times-daily dosing for improving hemoglobin and ferritin levels in both pregnant women and infants, with fewer side effects and better compliance reported for the once-daily regimen 23469. Higher frequency dosing (twice or three times daily) does not provide significant additional benefit and is associated with more gastrointestinal side effects, such as diarrhea and stomach pain 246.
Special Populations: Pregnancy and Adolescents
- Pregnant Women: Daily supplementation with 60–65 mg elemental iron is effective for preventing and treating anemia. Once-daily dosing is generally preferred due to fewer side effects and better adherence 234.
- Adolescents: Once-weekly supplementation with 150 mg ferrous sulfate has been shown to improve iron status and treat iron deficiency anemia effectively, suggesting that lower-frequency dosing can be considered in some populations to improve compliance and reduce side effects .
Iron Absorption and Dosing Strategies
Studies indicate that splitting the daily dose (e.g., taking iron twice a day) can increase levels of hepcidin, a hormone that reduces iron absorption. Therefore, taking the full dose once daily or even on alternate days may optimize iron absorption and minimize side effects . Alternate-day dosing (e.g., 60 mg every other day) has also been shown to improve iron absorption compared to consecutive daily dosing in iron-depleted women .
Iron Supplementation in Restless Legs Syndrome (RLS)
For adults with restless legs syndrome and low ferritin (≤75 μg/L), a guideline recommends ferrous sulfate 325 mg (65 mg elemental iron) with 100 mg vitamin C, taken twice daily, to improve symptoms and increase ferritin levels .
Safety and Tolerability
Daily supplementation with 60 mg ferrous sulfate is generally safe and does not increase the risk of adverse effects, including gut inflammation or infection, in non-anemic healthy adults 510. Side effects are more common with higher or more frequent dosing, but are usually mild and manageable 246.
Conclusion
The most widely supported guideline for ferrous sulfate supplementation is 60–65 mg elemental iron once daily for adults, including pregnant women, with adjustments for specific conditions such as RLS or adolescent supplementation. Once-daily dosing is effective, better tolerated, and improves adherence compared to multiple daily doses. Alternate-day dosing may further optimize absorption in some cases. Always consider individual patient needs and consult a healthcare provider for personalized recommendations.
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