Mutual absorption reduction
Take tetracyclines 2 hours before or 4 hours after iron.
Reduces antibiotic absorption
Take fluoroquinolones 2 hours before or 4-8 hours after iron.
Reduces drug absorption
Separate administration. Monitor drug levels.
Reduces drug absorption
Separate dosing times.
Reduces drug absorption
Separate by 4+ hours.
Reduces drug absorption
Take levothyroxine 2+ hours before iron.
Reduces drug absorption
Separate administration.
Reduces iron absorption
May need higher iron doses or alternate-day dosing.
Reduces drug absorption
Separate by 2+ hours.
Reduces iron absorption
Take at separate times if using calcium citrate.
Reduces drug absorption
Separate by 2+ hours.
Reduces drug absorption
Separate by 2+ hours.
Reduces iron absorption
Take at separate times.
Reduces iron absorption
Don't take iron with yerba mate.
Mixed evidence
Monitor iron levels if taking high-dose curcumin.
Mutual absorption reduction
Take at separate times if concerned.
Reduces absorption
No action needed.
△ KEY RULE: Iron chelates many drugs in the gut. Take iron at least 2 hours before or 3 hours after medications.
Not Prohibited. Not on the 2026 WADA list.
Reference identifiers on this page are being re-verified against PubMed. Some may not yet link to the paper named beside them.
**, Stoffel NU et al. "Iron absorption from oral iron supplements given on consecutive versus alternate days and as single morning doses versus twice-daily split doses." *Lancet Haematol*, 2017. Key finding: Alternate-day iron dosing results in better fractional absorption than daily dosing.
Iron absorption from oral iron supplements given on consecutive versus alternate days and as single morning doses versus twice-daily split doses.. (2017). PMID: 33232588
**, Moretti D et al. "Oral iron supplements increase hepcidin and decrease iron absorption from daily or twice-daily doses." *Blood*, 2015. Key finding: Single daily dose in the morning maximizes absorption; twice-daily dosing paradoxically reduces total absorption.
Oral iron supplements increase hepcidin and decrease iron absorption from daily or twice-daily doses.. (2015). PMID: 29323692
**, Camaschella C. "Iron deficiency." *Blood*, 2019. Key finding: Comprehensive review of iron deficiency pathophysiology, diagnosis, and treatment, the go-to reference for iron metabolism.
Iron deficiency.. (2019). PMID: 31447418
**, Pasricha SR et al. "Iron deficiency." *Lancet*, 2021. Key finding: Iron deficiency affects >1 billion people globally. Ferritin <30 μg/L is the most useful single test for iron deficiency.
Iron deficiency.. (2021). PMID: 32098519
**, Ponikowski P et al. "Ferric carboxymaltose for iron deficiency at discharge after acute heart failure." *Lancet*, 2020. Key finding: IV iron at discharge reduced heart failure hospitalizations by 26%.
Ferric carboxymaltose for iron deficiency at discharge after acute heart failure.. (2020). PMID: 30879237
Based on independent third-party laboratory analysis
Category pass rate: ~85% pass rate. Form and absorption are more important than label accuracy.
Independently graded against 178,763 indexed supplements and 757 reviewed supplement and medication pairs, sourced from PubMed, FDA CAERS, openFDA, and NIH DSLD | Last updated: April 5, 2026
Not medical advice. Based on published clinical research and systematic reviews.
Safety
Levothyroxine
Take at different times
Separate from thyroid hormone dose by at least 4 hours. Take Levothyroxine on an empty stomach 30 to 60 minutes before food, coffee, or supplements.
Simultaneous ingestion of ferrous sulfate and thyroxine causes a variable reduction in thyroxine efficacy that is clinically significant in some patients, leading to hypothyroidism.
Take Levothyroxine at least 4 hours apart from iron supplements. Iron can reduce Levothyroxine absorption by 30 to 50 percent.
Iron binds to levothyroxine in the gastrointestinal tract, forming an insoluble complex that reduces the absorption and bioavailability of the thyroid hormone.
Tetracycline and doxycycline
Take at different times
Take ciprofloxacin at least 2 hours before or 6 hours after iron. Take levofloxacin at least 2 hours before or after iron. Take moxifloxacin at least 4 hours before or 8 hours after iron. For any other fluoroquinolone or a tetracycline, ask your pharmacist how far apart to take them, because iron reduces how much of the antibiotic is absorbed.
Concomitant use of iron supplements and fluoroquinolones or tetracyclines significantly impairs the oral absorption and bioavailability of the antibiotics, potentially leading to treatment failure.
Iron forms insoluble chelates with fluoroquinolones and tetracyclines in the gastrointestinal tract. This chelation prevents the absorption of both the antibiotic and the iron into the bloodstream.
Fluoroquinolones
Take at different times
Take ciprofloxacin at least 2 hours before or 6 hours after iron. Take levofloxacin at least 2 hours before or after iron. Take moxifloxacin at least 4 hours before or 8 hours after iron. For any other fluoroquinolone or a tetracycline, ask your pharmacist how far apart to take them, because iron reduces how much of the antibiotic is absorbed.
Concomitant use of iron supplements and fluoroquinolones or tetracyclines significantly impairs the oral absorption and bioavailability of the antibiotics, potentially leading to treatment failure.
Iron forms insoluble chelates with fluoroquinolones and tetracyclines in the gastrointestinal tract. This chelation prevents the absorption of both the antibiotic and the iron into the bloodstream.
Antacids, PPIs, H2 blockers
Levodopa (Parkinson's)
Methyldopa
Timing Separation Rules
Educational information only. This is not medical advice. These statements have not been evaluated by the FDA. Talk to your prescriber before starting, stopping, or combining any supplement with prescription medication.