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 1 citation row for the Calcium + Erythromycin pair, each linking to PubMed by PMID where available. Full sourcing methodology at https://nutristackapp.com/methodology/interactions.

Supplement × Prescription·timing-sensitive·Insufficient evidence

Calcium + Erythromycin

Q: Can I take Calcium and Erythromycin together?

Yes, if you separate them in time. Calcium and Erythromycin have a documented timing-sensitive interaction. Polyvalent cations such as calcium can bind to some oral antibiotics and reduce absorption. While erythromycin is less prone to cation chelation than tetracyclines or fluoroquinolones, separating high-dose calcium supplements from oral erythromycin is a prudent precaution to ensure consistent absorption.

Q: How does this affect a NutriStack Stack Score?

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

Timing Sensitive Insufficient evidence

Polyvalent cations such as calcium can bind to some oral antibiotics and reduce absorption. While erythromycin is less prone to cation chelation than tetracyclines or fluoroquinolones, separating high-dose calcium supplements from oral erythromycin is a prudent precaution to ensure consistent absorption.

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

Calcium and Erythromycin

Pair type

Timing Sensitive

Evidence

Insufficient

Source citations

Scope

Supplement × Prescription

Last verified

June 4, 2026

Timing SensitiveInsufficient evidence

What is happening. Polyvalent cations such as calcium can bind to some oral antibiotics and reduce absorption. While erythromycin is less prone to cation chelation than tetracyclines or fluoroquinolones, separating high-dose calcium supplements from oral erythromycin is a prudent precaution to ensure consistent absorption.

Mechanism. Potential formation of poorly absorbed complexes between calcium and the antibiotic in the gut, reducing antibiotic bioavailability.

Recommendation. Separate calcium supplements from oral erythromycin by at least 2 hours where practical. Take erythromycin as directed relative to food per the specific formulation instructions.

Timing

Timing & separation.

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

Minimum separation

120

Stack Score

How it moves the number.

Effect on the composite score

If both Calcium and Erythromycin 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

1Neuvonen PJ. Interactions with the absorption of tetracyclines and other antibacterials. Drugs. 1976.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