What kind of interaction is it?

Timing-sensitive: the two substances can be taken on the same day but should be separated by a minimum time window.

Is this interaction backed by published research?

Yes. NutriStack lists 2 citation rows for the Cholestyramine + Iron pair, each linking to PubMed by PMID where available. Full sourcing methodology at https://nutristackapp.com/methodology/interactions.

Supplement × Prescription·timing-sensitive·Emerging evidence

Cholestyramine + Iron

Q: Can I take Cholestyramine and Iron together?

Yes, if you separate them in time. Cholestyramine and Iron have a documented timing-sensitive interaction. Cholestyramine can bind oral iron in the gastrointestinal tract and reduce its absorption when taken concurrently, potentially diminishing the efficacy of iron supplementation for treating or preventing deficiency.

Q: How does this affect a NutriStack Stack Score?

-5 to your Stack Score per scored timing-sensitive row.

Timing Sensitive Emerging evidence

Cholestyramine can bind oral iron in the gastrointestinal tract and reduce its absorption when taken concurrently, potentially diminishing the efficacy of iron supplementation for treating or preventing deficiency.

Supplement × Prescription

Open the interaction checker → Read the methodology

From the database

What the row says.

Every entry follows the same shape: what is happening, the mechanism, and the recommendation.

Substances

Cholestyramine and Iron

Pair type

Timing Sensitive

Evidence

Emerging

Source citations

Scope

Supplement × Prescription

Last verified

June 4, 2026

Timing SensitiveEmerging evidence

What is happening. Cholestyramine can bind oral iron in the gastrointestinal tract and reduce its absorption when taken concurrently, potentially diminishing the efficacy of iron supplementation for treating or preventing deficiency.

Mechanism. The cationic-binding and bulk-binding properties of the anion-exchange resin can sequester iron salts in the gut lumen, reducing dissolved iron available for absorption.

Recommendation. Take iron supplements at least 1 hour before or 4 to 6 hours after cholestyramine to avoid binding. Monitor hemoglobin and ferritin if iron deficiency is being treated during sequestrant therapy.

Timing

Timing & separation.

Space the doses apart by at least this window to avoid the conflict.

Minimum separation

240

Stack Score

How it moves the number.

Effect on the composite score

If both Cholestyramine and Iron 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 at /methodology/stack-score.

Sources

Sources, by evidence tier.

Every claim on this page is cited. PMIDs link straight to PubMed.

Reference material

1Thomas FB, et al. Inhibition of intestinal iron absorption by cholestyramine. Am J Clin Nutr. 1971.Needs sourceNo link
2Questran (cholestyramine) US prescribing information. Drug interactions: separate dosing of concomitant oral medications.Needs sourceNo link

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One pair was the worked example.

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Open the interaction checker → Browse the research index