Drug interactions
calcium salts (with magnesium) + oral iron (ferrous salts)
For healthcare professionals — reference only. This page is a brief summary, not medical advice and not a substitute for official labeling or clinical judgement. Always verify before prescribing or dispensing.
Overview
Calcium (and magnesium) can reduce gastrointestinal absorption of oral ferrous iron, potentially diminishing hematologic response.
Mechanism of action
Polyvalent cations (Ca2+, Mg2+) interfere with iron absorption via GI complexation/competition, lowering bioavailability.
Clinical management
Avoid coadministration; separate doses by at least 2 hours (prefer iron on empty stomach). Monitor hemoglobin and ferritin in 4–8 weeks; adjust timing or therapy if response is suboptimal.
References
- Calcium carbonate and ferrous sulfate Interactions — Drugs.com
- Lexicomp Interactions: Calcium Salts + Iron Salts — Lexicomp
Frequently asked questions
Can I take calcium salts (with magnesium) with oral iron (ferrous salts)?
The interaction is rated: Moderate. Calcium (and magnesium) can reduce gastrointestinal absorption of oral ferrous iron, potentially diminishing hematologic response.
How serious is the interaction between calcium salts (with magnesium) and oral iron (ferrous salts)?
The interaction is rated: Moderate. Evidence level: High.
How is the interaction between calcium salts (with magnesium) and oral iron (ferrous salts) managed?
Avoid coadministration; separate doses by at least 2 hours (prefer iron on empty stomach). Monitor hemoglobin and ferritin in 4–8 weeks; adjust timing or therapy if response is suboptimal.
Why do calcium salts (with magnesium) and oral iron (ferrous salts) interact?
Polyvalent cations (Ca2+, Mg2+) interfere with iron absorption via GI complexation/competition, lowering bioavailability.
Full monographs, dosing and an interaction checker in the MediHelp app
Open the complete reference, check multi-drug interactions and use dosing tools in the MediHelp app.