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 Calcium + Itraconazole pair, each linking to PubMed by PMID where available. Full sourcing methodology at https://nutristackapp.com/methodology/interactions.

Supplement × Prescription·timing-sensitive·Moderate evidence

Calcium + Itraconazole

Q: Can I take Calcium and Itraconazole together?

Yes, if you separate them in time. Calcium and Itraconazole have a documented timing-sensitive interaction. Calcium supplements, particularly calcium carbonate, raise gastric pH and can substantially reduce the dissolution and absorption of itraconazole capsules, which require an acidic stomach environment to dissolve. This may lead to subtherapeutic antifungal concentrations and treatment failure.

Q: How does this affect a NutriStack Stack Score?

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

Timing Sensitive Moderate evidence

Calcium supplements, particularly calcium carbonate, raise gastric pH and can substantially reduce the dissolution and absorption of itraconazole capsules, which require an acidic stomach environment to dissolve. This may lead to subtherapeutic antifungal concentrations and treatment failure.

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 Itraconazole

Pair type

Timing Sensitive

Evidence

Moderate

Source citations

Scope

Supplement × Prescription

Last verified

June 4, 2026

Timing SensitiveModerate evidence

What is happening. Calcium supplements, particularly calcium carbonate, raise gastric pH and can substantially reduce the dissolution and absorption of itraconazole capsules, which require an acidic stomach environment to dissolve. This may lead to subtherapeutic antifungal concentrations and treatment failure.

Mechanism. Calcium carbonate neutralizes gastric acid and increases intragastric pH; itraconazole capsule dissolution and oral bioavailability are highly acid-dependent, so elevated pH decreases drug absorption.

Recommendation. Separate calcium supplements from itraconazole capsules by at least 2 hours. Take itraconazole capsules with food and an acidic beverage (such as a cola) when possible. The oral solution and SUBA formulation are less pH-dependent and may be preferred if frequent calcium use is required. Discuss persistent infections with the prescriber.

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 Itraconazole 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

1Jaruratanasirikul S, Kleepkaew A. Influence of an acidic beverage (Coca-Cola) on the absorption of itraconazole. Eur J Clin Pharmacol. 1997.Needs sourceNo link
2Lange D, et al. Effect of a cola beverage on the bioavailability of itraconazole in the presence of H2 blockers. J Clin Pharmacol. 1997.Needs sourceNo link

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Open the interaction checker → Browse the research index