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

Supplement × Prescription·timing-sensitive·Moderate evidence

Ampicillin + Calcium

Q: Can I take Ampicillin and Calcium together?

Yes, if you separate them in time. Ampicillin and Calcium have a documented timing-sensitive interaction. Calcium is a divalent cation that can theoretically chelate beta-lactam antibiotics, and large meals or dairy can reduce ampicillin absorption. Ampicillin bioavailability is improved on an empty stomach. The chelation effect with calcium is much weaker than with tetracyclines and is rarely clinically significant for ampicillin.

Q: How does this affect a NutriStack Stack Score?

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

Timing Sensitive Moderate evidence

Calcium is a divalent cation that can theoretically chelate beta-lactam antibiotics, and large meals or dairy can reduce ampicillin absorption. Ampicillin bioavailability is improved on an empty stomach. The chelation effect with calcium is much weaker than with tetracyclines and is rarely clinically significant for ampicillin.

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

Ampicillin and Calcium

Pair type

Timing Sensitive

Evidence

Moderate

Source citations

Scope

Supplement × Prescription

Last verified

June 4, 2026

Timing SensitiveModerate evidence

What is happening. Calcium is a divalent cation that can theoretically chelate beta-lactam antibiotics, and large meals or dairy can reduce ampicillin absorption. Ampicillin bioavailability is improved on an empty stomach. The chelation effect with calcium is much weaker than with tetracyclines and is rarely clinically significant for ampicillin.

Mechanism. Food and divalent calcium reduce gastrointestinal absorption of ampicillin; calcium may also form weak complexes with the beta-lactam in the gut lumen.

Recommendation. Take ampicillin on an empty stomach, at least 1 hour before or 2 hours after food and calcium-containing supplements or dairy products, to maximize absorption. Separate calcium supplements from ampicillin by about 2 hours.

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 Ampicillin and Calcium 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

1Welling PG, Huang H, Koch PA, et al. Bioavailability of ampicillin and amoxicillin in fasted and nonfasted subjects. J Pharm Sci. 1977.Needs sourceNo link

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Open the interaction checker → Browse the research index