Ferrous sulfate
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Ferrous Sulfate: Uses, Efficacy, and Side Effects
Introduction to Ferrous Sulfate
Ferrous sulfate is a widely used iron supplement, primarily prescribed to treat iron deficiency anemia. Despite its effectiveness, it is associated with several side effects and varying degrees of efficacy depending on the population and condition being treated.
Gastrointestinal Side Effects of Ferrous Sulfate
Significant Increase in GI Side Effects
Ferrous sulfate is known to cause significant gastrointestinal (GI) side effects. A systematic review and meta-analysis of 43 trials involving 6,831 adult participants found that ferrous sulfate significantly increased the risk of GI side effects compared to placebo (OR = 2.32) and intravenous (IV) iron (OR = 3.05) 1. This effect was consistent across different subgroups, including patients with inflammatory bowel disease (IBD) and pregnant women 1.
Comparative Tolerability
When compared to other iron supplements, ferrous sulfate tends to have more frequent GI side effects. For instance, lactoferrin, a milk-derived iron-binding glycoprotein, showed better gastrointestinal tolerance and fewer side effects than ferrous sulfate in a meta-analysis 3.
Efficacy in Treating Iron Deficiency
Bioavailability and Iron Absorption
Ferrous sulfate is more bioavailable than other forms of iron, such as ferrous fumarate and reduced iron + Na2EDTA, when added to fortified foods. A study on preschoolers in Mexico found that iron absorption from ferrous sulfate was significantly higher (7.9%) compared to ferrous fumarate (2.43%) and reduced iron + Na2EDTA (1.4%) 5.
Treatment of Anemia in Infants
A randomized controlled trial in rural Ghana compared the efficacy of single versus three-times-daily doses of ferrous sulfate drops in treating anemia in infants. Both dosing regimens resulted in similar rates of successful treatment, with minimal side effects, suggesting that a single daily dose could improve adherence without compromising efficacy 4.
Comparison with Other Iron Supplements
In patients with chronic kidney disease (CKD) and iron deficiency, ferric citrate was found to be more effective than ferrous sulfate in increasing transferrin saturation (TSAT) and ferritin levels over 12 weeks 8. This suggests that alternative iron supplements may offer better outcomes in specific patient populations.
Special Populations
Children with Autism Spectrum Disorders
A study on children with autism spectrum disorders and low normal ferritin levels found that ferrous sulfate supplementation improved iron status but did not significantly improve primary measures of insomnia 2. This indicates that while ferrous sulfate can enhance iron levels, its impact on related conditions like sleep disturbances may be limited.
Toddlers and Complementary Foods
In a study assessing the efficacy of ferrous sulfate and ferrous gluconate as fortificants in complementary baby food, both forms were found to be effective in improving iron status and reducing the prevalence of anemia in toddlers 7. This highlights the potential of ferrous sulfate in pediatric nutrition programs.
Safety Concerns
Toxicity and Poisoning
Despite its widespread use, ferrous sulfate can be toxic in high doses. There have been reports of fatal poisoning, particularly in children. One case involved a 29-month-old boy who ingested a large quantity of ferrous sulfate tablets, leading to severe gastrointestinal irritation, cyanosis, and peripheral vascular collapse 10. This underscores the importance of careful dosing and storage of iron supplements.
Conclusion
Ferrous sulfate is an effective iron supplement for treating iron deficiency anemia, but it is associated with significant gastrointestinal side effects and potential toxicity. Its efficacy and tolerability can vary depending on the population and condition being treated. Alternative iron supplements like lactoferrin and ferric citrate may offer better outcomes in certain cases. Careful consideration of dosing and monitoring is essential to minimize adverse effects and ensure patient safety.
Sources and full results
Most relevant research papers on this topic
Ferrous Sulfate Supplementation Causes Significant Gastrointestinal Side-Effects in Adults: A Systematic Review and Meta-Analysis
Ferrous sulfate supplementation significantly increases the risk of gastrointestinal side-effects in adults, but the relationship with dose remains unclear.
Meta-Analysis
Rigorous Journal
Highly CitedRandomized, Placebo-Controlled Trial of Ferrous Sulfate to Treat Insomnia in Children With Autism Spectrum Disorders.
Ferrous sulfate supplementation improved iron status but did not significantly improve sleep onset latency or wake time after sleep onset in children with autism spectrum disorders.
RCTComparative Effects between Oral Lactoferrin and Ferrous Sulfate Supplementation on Iron-Deficiency Anemia: A Comprehensive Review and Meta-Analysis of Clinical Trials
Lactoferrin supplementation is a superior option for improving serum iron parameters and hemoglobin levels compared to ferrous sulfate, with its anti-inflammation effect potentially explaining its efficacy.
Meta-Analysis
Very Rigorous JournalRandomized, controlled trial of single versus 3-times-daily ferrous sulfate drops for treatment of anemia.
A single-dose daily regimen of ferrous sulfate drops for anemia treatment in infants resulted in similar success rates and minimal side effects, potentially improving adherence to treatment.
RCT
Large Human TrialHighly CitedFerrous sulfate is more bioavailable among preschoolers than other forms of iron in a milk-based weaning food distributed by PROGRESA, a national program in Mexico.
Ferrous sulfate is more bioavailable than ferrous fumarate or reduced iron + Na(2)EDTA in milk-based fortified foods for preschoolers aged 2-3 years, meeting their daily iron requirements.
RCTFerrous sulfate toxicity; report of a fatal case.
Ferrous sulfate toxicity is a rare but potentially fatal condition, highlighting the need for careful monitoring and research on this potentially harmful drug.
Case ReportFerrous Gluconate and Ferrous Sulfate Added to a Complementary Food Distributed by the Mexican Nutrition Program Oportunidades Have a Comparable Efficacy to Reduce Iron Deficiency in Toddlers
Ferrous gluconate and ferrous sulfate fortification in Nutrisano toddler food both have a comparable efficacy in improving iron status and reducing anemia in toddlers.
RCTEffect of Ferric Citrate versus Ferrous Sulfate on Iron and Phosphate Parameters in Patients with Iron Deficiency and CKD: A Randomized Trial.
Ferric citrate treatment for 12 weeks resulted in a greater increase in TSAT and ferritin concentrations compared to ferrous sulfate in individuals with moderate to severe CKD and iron deficiency.
RCTFERROUS SULFATE POISONING
Ferrous sulfate poisoning in children can be fatal, with severe gastrointestinal irritation, cyanosis, and peripheral vascular collapse.
Case Report