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Iron Sulfate

Ferrous Sulfate

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Meta Information

ID:iron-sulfate
Name:
Schema Version:2.4_uniform_evidence_2026_06_18

Created

2026-05-10T18:36:39.412812Z

Model

Gemini 3.1 Pro (High)

Interactions

Target id:
/intervention/bisphosphonates
Target name:
Bisphosphonates
Severity:
moderate
Interaction type:
diminishing
Nature:
temporal
Temporal spacing:
Hours before target:
2
Hours after target:
2
Description:
Iron binds to bisphosphonates, forming a complex that dramatically reduces the absorption of the bone medication.
Actionable advice:
Doses should be separated by at least 2 hours.
Validation status:
validated_via_pubmed
Evidence tier:
tier_b
Evidence basis:
pubmed_abstract_verbatim
Evidence anchors:
Exact phrase from label:
Concurrent ingestion of iron caused a marked decrease in the absorption of clodronate.
Label source:
PubMed: Pharmacology & toxicology (1994)
Exact phrase from label:
The new method has been applied to the study of the composition of iron (III) complexes with three bisphosphonate drugs: alendronate, etidronate, and ibandronate. The mole ratio was found to be 1:1 with the three investigated bisphosphonates and results were further confirmed by Job's and mole ratio methods.
Label source:
PubMed: Chemistry Central journal (2018)
Exact phrase from label:
Alendronate (ALN), a kind of FDA-approved bisphosphonates with metal-chelating capability, is initially certified to selectively bind to intracellular Fe3+ theoretically and experimentally in this study.
Label source:
PubMed: Advanced science (Weinheim, Baden-Wurttemberg, Germany) (2022)
Action type:
separate
Target id:
/intervention/levothyroxine
Target name:
Levothyroxine
Severity:
moderate
Interaction type:
diminishing
Nature:
temporal
Temporal spacing:
Hours before target:
4
Hours after target:
4
Description:
Iron binds to levothyroxine, significantly reducing the absorption and effectiveness of the thyroid hormone medication.
Actionable advice:
Doses should be separated by at least 4 hours.
Validation status:
validated_via_pubmed
Evidence tier:
tier_b
Evidence basis:
pubmed_abstract_verbatim
Evidence anchors:
Exact phrase from label:
When iron and thyroxine were mixed together in vitro, a poorly soluble purple complex appeared that indicated the binding of iron to thyroxine.
Label source:
PubMed: Annals of internal medicine (1992)
Exact phrase from label:
Simultaneous ingestion of ferrous sulfate and thyroxine causes a variable reduction in thyroxine efficacy that is clinically significant in some patients. The interaction is probably caused by the binding of iron to thyroxine.
Label source:
PubMed: Annals of internal medicine (1992)
Exact phrase from label:
A decrease in the absorption of LT4 is established and clinically significant when administered concomitantly with cholestyramine, colesevelam, lanthanum, calcium carbonate, calcium citrate, calcium acetate, iron sulfate, ciprofloxacin, aluminum hydroxide, sevelamer, or proton pump inhibitors.
Label source:
PubMed: Clinical therapeutics (2017)
Action type:
separate
Target id:
/intervention/levodopa
Target name:
Levodopa
Severity:
moderate
Interaction type:
diminishing
Nature:
temporal
Temporal spacing:
Hours before target:
2
Hours after target:
2
Description:
Iron can bind to levodopa in the gut, reducing the absorption and effectiveness of this medication.
Actionable advice:
Doses should be separated by at least 2 hours.
Validation status:
validated_via_pubmed
Evidence tier:
tier_b
Evidence basis:
pubmed_abstract_verbatim
Evidence anchors:
Exact phrase from label:
When levodopa was taken with ferrous sulfate there was a 55% decrease in peak levodopa levels (3.6 +/- 2.6 vs 1.6 +/- 0.82 nmol/ml; p less than 0.05) and a 51% decrease in AUC (257 +/- 133 vs 125 +/- 51 nmol.min/ml; p less than 0.01).
Label source:
PubMed: Clinical pharmacology and therapeutics (1989)
Exact phrase from label:
Chelation of iron by levodopa is the likely mechanism for this drug interaction.
Label source:
PubMed: Clinical pharmacology and therapeutics (1989)
Exact phrase from label:
Ferrous sulfate decreases L-dopa bioavailability in humans probably as a result of binding of L-dopa by iron in the gastrointestinal tract.
Label source:
PubMed: Canadian journal of physiology and pharmacology (1990)
Exact phrase from label:
Contrastingly, high-protein diet and ferrous sulfate supplements can negatively affect levodopa pharmacokinetics and effectiveness.
Label source:
PubMed: Current neuropharmacology (2022)
Action type:
separate
Target id:
/class/bile-acid-sequestrants
Target name:
Bile Acid Sequestrants
Severity:
minor
Interaction type:
diminishing
Nature:
temporal
Temporal spacing:
Hours before target:
4
Hours after target:
4
Description:
These drugs can bind to iron in the intestine, significantly preventing its absorption into the body.
Actionable advice:
Doses should be separated by at least 4 hours.
Validation status:
validated_via_pubmed
Evidence tier:
tier_b
Evidence basis:
pubmed_abstract_verbatim
Evidence anchors:
Exact phrase from label:
A diminished iron absorption due to resin binding could account for the reported disturbance in iron balance.
Label source:
PubMed: Digestive diseases and sciences (1985)
Exact phrase from label:
Both resins bound to a high extent vitamin B12-intrinsic factor complex, folic acid and iron citrate; in addition, cholestyramine also caused appreciable binding of calcium.
Label source:
PubMed: Arzneimittel-Forschung (1979)
Exact phrase from label:
Numerous drugs, including tetracycline and cholestyramine, bind iron and decrease its absorption.
Label source:
PubMed: Federation proceedings (1985)
Action type:
separate
Target id:
/intervention/egcg-green-tea
Target name:
Egcg
Severity:
major
Interaction type:
diminishing
Nature:
temporal
Temporal spacing:
Hours before target:
4
Hours after target:
4
Description:
EGCG, a polyphenol in green tea, strongly binds to iron, significantly inhibiting its absorption from the gut.
Actionable advice:
Doses should be separated by at least 4 hours.
Validation status:
anecdotal
Evidence tier:
tier_d
Evidence basis:
anecdotal_summary
Evidence anchors:
Exact phrase from label:
Some foods like eggs, whole grain breads, cereal, dairy products, coffee, and tea may make this drug not work as well.
Label source:
Anecdotal: MSKCC
Action type:
separate
Target id:
/intervention/green-tea-extract
Target name:
Green Tea Extract
Severity:
major
Interaction type:
diminishing
Nature:
temporal
Temporal spacing:
Hours before target:
4
Hours after target:
4
Description:
Polyphenols in green tea extract bind tightly to iron, which significantly reduces its absorption.
Actionable advice:
Doses should be separated by at least 4 hours.
Validation status:
anecdotal
Evidence tier:
tier_d
Evidence basis:
anecdotal_summary
Evidence anchors:
Exact phrase from label:
This product can decrease the amount of iron you get from food/supplements.
Label source:
Anecdotal: WebMD
Action type:
separate
Target id:
/dietary/polyphenol-rich-foods
Target name:
Polyphenol-rich Foods
Severity:
moderate
Interaction type:
diminishing
Nature:
absolute
Temporal spacing:
Hours before target:
0
Hours after target:
0
Description:
Polyphenols in foods like tea, coffee, and berries bind to iron, strongly inhibiting its absorption.
Actionable advice:
Iron is best taken between meals.
Validation status:
validated_via_pubmed
Evidence tier:
tier_b
Evidence basis:
pubmed_abstract_verbatim
Evidence anchors:
Exact phrase from label:
All beverages were potent inhibitors of Fe absorption and reduced absorption in a dose-dependent fashion depending on the content of total polyphenols. Compared with a water control meal, beverages containing 20-50 mg total polyphenols/serving reduced Fe absorption from the bread meal by 50-70%, whereas beverages containing 100-400 mg total polyphenols/serving reduced Fe absorption by 60-90%.
Label source:
PubMed: The British journal of nutrition (1999)
Exact phrase from label:
The phenolic compounds (phenolic monomers, polyphenols, tannins) are considered to interfere with iron absorption by complex formation with iron in the gastro-intestinal lumen, making the iron less available for absorption.
Label source:
PubMed: European journal of clinical nutrition (1989)
Exact phrase from label:
Polyphenols present in coffee and tea inhibited iron absorption in a dose-dependent manner. American-type coffee did not modify iron absorption significantly, whereas both espresso-type coffee and tea reduced iron absorption from ferrochel by 50% (P: < 0. 05).
Label source:
PubMed: The Journal of nutrition (2000)
Action type:
informational_none
Target id:
/class/proton-pump-inhibitors
Target name:
Proton Pump Inhibitors
Severity:
minor
Interaction type:
diminishing
Nature:
absolute
Temporal spacing:
Hours before target:
0
Hours after target:
0
Description:
These drugs strongly reduce stomach acid, which is essential for dissolving and absorbing iron supplements effectively.
Actionable advice:
It is a good idea to talk to a doctor about iron form.
Validation status:
validated_via_pubmed
Evidence tier:
tier_b
Evidence basis:
pubmed_abstract_verbatim
Evidence anchors:
Exact phrase from label:
Gastric acid is one of the important factors for optimum absorption of iron. Proton pump inhibitors are very commonly prescribed medications. One of the debated effects of proton pump inhibitors is on oral iron absorption.
Label source:
PubMed: American journal of therapeutics (2012)
Exact phrase from label:
Proton pump inhibitor therapy reduces the absorption of non-heme iron and this effect has been employed in the management of hemochromatosis. It may also retard clinical response to iron supplementation.
Label source:
PubMed: The American journal of gastroenterology (2009)
Exact phrase from label:
Gastric acid plays a crucial role in non-haem iron absorption and the authors performed a case review and intervention study to investigate if PPI-induced suppression of gastric acid would reduce dietary iron absorption in C282Y homozygous patients.
Label source:
PubMed: Gut (2007)
Action type:
informational_none
Target id:
/intervention/calcium-akg
Target name:
Calcium Alpha-Ketoglutarate
Severity:
moderate
Interaction type:
diminishing
Nature:
temporal
Temporal spacing:
Hours before target:
2
Hours after target:
2
Description:
Calcium competes with iron for the same absorption pathways in the gut, reducing iron uptake.
Actionable advice:
Doses should be separated by at least 2 hours.
Validation status:
validated_via_pubmed
Evidence tier:
tier_b
Evidence basis:
pubmed_abstract_verbatim
Evidence anchors:
Exact phrase from label:
All calcium supplements inhibited absorption of the iron supplement when taken with food. The absorption of dietary nonheme iron was also inhibited by all three supplements.
Label source:
PubMed: The American journal of clinical nutrition (1991)
Exact phrase from label:
Calcium is the only known component in the diet that may affect absorption of both nonheme and heme iron. However, the evidence for a calcium effect on iron absorption mainly comes from studies that did not isolate the effect of calcium from that of other dietary components, because it was detected in single-meal studies.
Label source:
PubMed: The Journal of nutrition (2011)
Exact phrase from label:
The addition of calcium reduced mean iron absorption by 18-27%, with the effect being stronger for high added calcium (P < 0.01).
Label source:
PubMed: The Journal of nutrition (2014)
Action type:
separate
Target id:
/intervention/calcium-citrate
Target name:
Calcium Citrate
Severity:
moderate
Interaction type:
diminishing
Nature:
temporal
Temporal spacing:
Hours before target:
2
Hours after target:
2
Description:
Calcium competes with iron for the same absorption pathways in the gut, reducing iron uptake.
Actionable advice:
Doses should be separated by at least 2 hours.
Validation status:
validated_via_primary_literature
Evidence tier:
tier_b
Evidence basis:
primary_literature_verbatim
Evidence anchors:
Exact phrase from label:
Using rodent models, calcium salts have been shown to prevent the promotion of haem-induced and red meat-induced colorectal carcinogenesis by limiting the bioavailability of the gut luminal haem iron.
Label source:
PubMed: Calcium-rich dairy matrix protects better than mineral calcium against colonic luminal haem-induced alterations in male rats. (PMID 38956092)
Action type:
separate
Target id:
/intervention/magnesium
Target name:
Magnesium
Severity:
major
Interaction type:
diminishing
Nature:
temporal
Temporal spacing:
Hours before target:
2
Hours after target:
2
Description:
Magnesium competes with iron for absorption in the intestine, potentially reducing the uptake of both minerals.
Actionable advice:
Doses should be separated by at least 2 hours.
Validation status:
anecdotal
Evidence tier:
tier_d
Evidence basis:
anecdotal_summary
Evidence anchors:
Exact phrase from label:
When treating deficiencies with high doses, taking both at the same time could lead to absorption competition, diminishing their effectiveness.
Label source:
Anecdotal: Verywell Health
Action type:
separate
Target id:
/intervention/zinc
Target name:
Zinc
Severity:
moderate
Interaction type:
diminishing
Nature:
temporal
Temporal spacing:
Hours before target:
2
Hours after target:
2
Description:
Zinc and iron compete for the same absorption pathways; high doses of one can reduce the other's absorption.
Actionable advice:
Doses should be separated by at least 2 hours.
Validation status:
validated_via_primary_literature
Evidence tier:
tier_b
Evidence basis:
primary_literature_verbatim
Evidence anchors:
Exact phrase from label:
The effect of inorganic zinc on the absorption of inorganic iron (Fe+2) from a solution was assessed in two studies on healthy male volunteers.
Label source:
PubMed: Inorganic zinc and the intestinal absorption of ferrous iron. (PMID 2502004)
Action type:
separate
Target id:
/intervention/famotidine
Target name:
Famotidine
Severity:
minor
Interaction type:
diminishing
Nature:
absolute
Temporal spacing:
Hours before target:
0
Hours after target:
0
Description:
This acid reducer lowers stomach acidity, which is necessary for the proper absorption of iron.
Actionable advice:
It is a good idea to talk to a doctor about iron form.
Validation status:
validated_via_pubmed
Evidence tier:
tier_b
Evidence basis:
pubmed_abstract_verbatim
Evidence anchors:
Exact phrase from label:
Malabsorption of dietary iron and cobalamin appears to result from inhibition of gastric secretion by the H2-receptor antagonists. This is of no clinical importance in short term treatment, but long term use of H2-receptor antagonists may theoretically contribute to the occurrence of iron or cobalamin deficiency anaemia.
Label source:
PubMed: Medical toxicology and adverse drug experience (1988)
Exact phrase from label:
Radioiron absorption tests in human volunteers demonstrated a modest but significant 28% reduction in the absorption of dietary nonheme iron from a meal that was preceded by the administration of 300 mg cimetidine.
Label source:
PubMed: Gastroenterology (1981)
Exact phrase from label:
Iron deficiency anemia is often listed among potential adverse effects of gastric acid-suppressive medications, given that gastric acidity promotes intestinal absorption of nonheme iron.
Label source:
PubMed: The American journal of the medical sciences (2019)
Action type:
informational_none
Target id:
/intervention/high-fiber-diet
Target name:
High-Fiber Diet
Severity:
moderate
Interaction type:
diminishing
Nature:
absolute
Temporal spacing:
Hours before target:
0
Hours after target:
0
Description:
Phytates found in high-fiber foods like whole grains and legumes can bind to iron, reducing absorption.
Actionable advice:
Iron is best taken between meals.
Validation status:
validated_via_pubmed
Evidence tier:
tier_b
Evidence basis:
pubmed_abstract_verbatim
Evidence anchors:
Exact phrase from label:
The inhibition of Fe absorption was strongly related to the amount of phytate added; 2 mg inhibited absorption by 18%, (p less than 0.001), 25 mg by 64% (p less than 0.001), and 250 mg by 82% (p less than 0.001).
Label source:
PubMed: The American journal of clinical nutrition (1989)
Exact phrase from label:
Dietary inhibitors such as calcium, phytates, polyphenols and enhancers such as ascorbic acid and proteins mainly influence iron bioavailability.
Label source:
PubMed: ACS omega (2022)
Exact phrase from label:
Plant-based diets in low-income countries (LICs) have a high content of phytic acid (myo-inositol hexaphosphate [InsP6]) and associated magnesium, potassium, and calcium salts. Together, InsP6 acid and its salts are termed "phytate" and are potent inhibitors of iron and zinc absorption.
Label source:
PubMed: Nutrition reviews (2018)
Action type:
informational_none
Target id:
/intervention/phytoestrogens-soy-isoflavones
Target name:
Phytoestrogens: Soy Isoflavones
Severity:
moderate
Interaction type:
diminishing
Nature:
temporal
Temporal spacing:
Hours before target:
2
Hours after target:
2
Description:
Soy products contain phytates and proteins that can significantly inhibit the absorption of iron supplements.
Actionable advice:
Doses and soy should be separated by 2 hours.
Validation status:
validated_via_pubmed
Evidence tier:
tier_b
Evidence basis:
pubmed_abstract_verbatim
Evidence anchors:
Exact phrase from label:
Iron absorption increased four- to fivefold when phytic acid was reduced from its native amount of 4.9-8.4 to less than 0.01 mg/g of isolate. Even relatively small quantities of residual phytate were strongly inhibitory and phytic acid had to be reduced to less than 0.3 mg/g of isolate (corresponding to less than 10 mg phytic acid/meal) before a meaningful increase in iron absorption was observed. However, even after removal of virtually all the phytic acid, iron absorption from the soy-protein meal was still only half that of the egg white control.
Label source:
PubMed: The American journal of clinical nutrition (1992)
Exact phrase from label:
Recent studies in normal men have demonstrated that soy products have a pronounced inhibitory effect on the absorption of nonheme dietary iron.
Label source:
PubMed: The American journal of clinical nutrition (1982)
Exact phrase from label:
Significant data indicate that inhibitors of iron absorption include phytate, polyphenols, soy protein and calcium, and enhancers include animal tissue and ascorbic acid.
Label source:
PubMed: Nutrients (2013)
Action type:
separate
Target id:
/intervention/curcumin
Target name:
Curcumin
Severity:
moderate
Interaction type:
diminishing
Nature:
temporal
Temporal spacing:
Hours before target:
3
Hours after target:
3
Description:
Curcumin is an iron chelator, meaning it can bind to iron and inhibit its absorption.
Actionable advice:
Doses should be separated by at least 3 hours.
Validation status:
anecdotal
Evidence tier:
tier_d
Evidence basis:
anecdotal_summary
Evidence anchors:
Exact phrase from label:
Turmeric may hinder iron absorption, posing difficulties for those with iron deficiency or individuals taking oral iron supplements.
Label source:
Anecdotal: Verywell Health
Action type:
separate
Target id:
/intervention/quercetin
Target name:
Quercetin
Severity:
moderate
Interaction type:
diminishing
Nature:
temporal
Temporal spacing:
Hours before target:
3
Hours after target:
3
Description:
Quercetin is a polyphenol that acts as an iron chelator, binding to it and reducing absorption.
Actionable advice:
Doses should be separated by at least 3 hours.
Validation status:
unvalidatable
Evidence tier:
tier_e
Evidence basis:
unvalidatable
Evidence anchors:
Source url:
Scientific literature support not found
Exact phrase from label:
Label source:
Action type:
separate
Target id:
/intervention/caffeine
Target name:
Caffeine
Severity:
moderate
Interaction type:
diminishing
Nature:
temporal
Temporal spacing:
Hours before target:
1
Hours after target:
1
Description:
Compounds like tannins in coffee and tea can bind to iron, reducing its absorption by over 50%.
Actionable advice:
Coffee and tea are best avoided within 1 hour before or after iron.
Validation status:
anecdotal
Evidence tier:
tier_d
Evidence basis:
anecdotal_summary
Evidence anchors:
Exact phrase from label:
They found that in women who took the supplement in the morning with coffee, iron absorption was reduced by 66%.
Label source:
Anecdotal: Healthline
Action type:
separate
Target id:
/intervention/vitamin-c
Target name:
Vitamin C
Severity:
minor
Interaction type:
synergistic
Nature:
absolute
Temporal spacing:
Hours before target:
0
Hours after target:
0
Description:
Vitamin C significantly enhances the absorption of non-heme iron by converting it to a more usable form.
Actionable advice:
They are generally best taken together for better absorption.
Validation status:
validated_via_primary_literature
Evidence tier:
tier_b
Evidence basis:
primary_literature_verbatim
Evidence anchors:
Exact phrase from label:
OBJECTIVE: Our goal was to examine the effect of vitamin C on nonheme-iron absorption from a complete diet rather than from single meals.
Label source:
PubMed: Effect of ascorbic acid intake on nonheme-iron absorption from a complete diet. (PMID 11124756)
Action type:
informational_none
Target id:
/intervention/digestive-enzymes
Target name:
Digestive Enzymes
Severity:
minor
Interaction type:
diminishing
Nature:
temporal
Temporal spacing:
Hours before target:
2
Hours after target:
2
Description:
Some enzyme formulas, particularly pancrelipase, can interfere with and reduce the absorption of iron supplements.
Actionable advice:
Doses should be separated by at least 2 hours.
Validation status:
validated_via_pubmed
Evidence tier:
tier_b
Evidence basis:
pubmed_abstract_verbatim
Evidence anchors:
Exact phrase from label:
Significant impairment of iron absorption was detected in both patients with cystic fibrosis and controls after administration of a preparation of pancreatic enzymes.
Label source:
PubMed: American journal of diseases of children (1960) (1989)
Exact phrase from label:
These findings suggest that long-term consumption of pancreatic enzymes by patients with cystic fibrosis may contribute to iron deficiency.
Label source:
PubMed: American journal of diseases of children (1960) (1989)
Action type:
separate
Target id:
/intervention/alpha-lipoic-acid
Target name:
Alpha-Lipoic Acid
Severity:
moderate
Interaction type:
diminishing
Nature:
temporal
Temporal spacing:
Hours before target:
2
Hours after target:
2
Description:
Alpha-lipoic acid can bind to iron, potentially reducing the absorption of both substances in the gut.
Actionable advice:
Doses should be separated by at least 2 hours.
Validation status:
unvalidatable
Evidence tier:
tier_e
Evidence basis:
unvalidatable
Evidence anchors:
Source url:
Scientific literature support not found
Exact phrase from label:
Label source:
Action type:
separate
Target id:
/intervention/milk-thistle
Target name:
Milk Thistle (Silymarin)
Severity:
moderate
Interaction type:
diminishing
Nature:
temporal
Temporal spacing:
Hours before target:
2
Hours after target:
2
Description:
Silymarin, the active component in milk thistle, can bind to iron and may reduce its absorption.
Actionable advice:
Doses should be separated by at least 2 hours.
Validation status:
anecdotal
Evidence tier:
tier_d
Evidence basis:
anecdotal_summary
Evidence anchors:
Exact phrase from label:
Silybin can also act as an iron chelator, further strengthening its antioxidant properties.
Label source:
Anecdotal: StatPearls
Action type:
separate
Target id:
/intervention/myo-inositol
Target name:
Myo-inositol
Severity:
minor
Interaction type:
diminishing
Nature:
temporal
Temporal spacing:
Hours before target:
2
Hours after target:
2
Description:
Inositols can form phytates that bind to iron, potentially reducing its absorption from the gut.
Actionable advice:
Doses should be separated by at least 2 hours.
Validation status:
unvalidatable
Evidence tier:
tier_e
Evidence basis:
unvalidatable
Evidence anchors:
Source url:
Scientific literature support not found
Exact phrase from label:
Label source:
Action type:
separate
Target id:
/intervention/copper
Target name:
Copper
Severity:
minor
Interaction type:
diminishing
Nature:
temporal
Temporal spacing:
Hours before target:
2
Hours after target:
2
Description:
High doses of copper can compete with iron for absorption, though this is rarely clinically significant.
Actionable advice:
High doses are best separated by 2 hours.
Validation status:
validated_via_primary_literature
Evidence tier:
tier_b
Evidence basis:
primary_literature_verbatim
Evidence anchors:
Exact phrase from label:
Copper in the presence of ascorbic acid inhibits non-heme Fe absorption at Cu/Fe 8/1 molar ratio.
Label source:
PubMed: Acute Copper and Ascorbic Acid Supplementation Inhibits Non-heme Iron Absorption in Humans. (PMID 26715577)
Action type:
separate