NutriStack
Iron and Risedronate, timing-sensitive.
Iron (Fe2+/Fe3+) forms tight, non-absorbable complexes with risedronate's phosphonate groups in the gut, blocking its already poor oral absorption. Taking the two together can wipe out most of the risedronate dose and leave bones unprotected.
One pair, every claim cited. The two substances, the type, the mechanism, the recommendation, and the primary literature.
Same shape as the other 1,729 pairs in the public database.
From the interaction database
What the row says.
Every entry follows the same shape: what is happening, the mechanism, the recommendation, and the primary literature.
At a glance
- Substances
- Iron and Risedronate
- Pair type
- Timing Sensitive
- Evidence (highest tier)
- Strong
- Source citations
- 2 sources
- Stack Score effect
- −5 to your Stack Score (per scored timing-sensitive row).
- Scope
- Supplement × Prescription
- Last verified
- May 30, 2026
Timing Sensitive · Strong evidence
Timing Sensitive
What is happening. Iron (Fe2+/Fe3+) forms tight, non-absorbable complexes with risedronate's phosphonate groups in the gut, blocking its already poor oral absorption. Taking the two together can wipe out most of the risedronate dose and leave bones unprotected.
Mechanism. Bisphosphonate phosphonate groups chelate polyvalent metal cations including Fe2+ and Fe3+, generating insoluble complexes that cannot be absorbed across the intestinal epithelium.
Recommendation. Take risedronate alone with plain water on an empty stomach, then wait at least 60 minutes before any iron supplement or iron-fortified food. If you take iron in the evening, you can dose risedronate the next morning without issue.
Minimum separation. 60
Sources (2)
- Kim JS, Jang SW, Son M, Kim BM, Kang MJ. Enteric-coated tablet of risedronate sodium in combination with phytic acid, a natural chelating agent, for improved oral bioavailability. Eur J Pharm Sci. 2016;82:36-42. PMID 26594027
- Wiesner A, Szuta M, Galanty A, Paśko P. Optimal Dosing Regimen of Osteoporosis Drugs in Relation to Food Intake as the Key for the Enhancement of the Treatment Effectiveness-A Concise Literature Review. Foods. 2021;10(4):720. PMID 33805435
Stack Score
How this pair moves the number.
Effect on the composite score
If both Iron and Risedronate are in the same stack, this pair applies −5 to your Stack Score (per scored timing-sensitive row).
The full algorithm, the clamping rules, and four worked stacks are documented at /methodology/stack-score.
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