Moderate interactionModerateSeparate by 3h

Calcium citrate and Tetracycline antibiotic: interaction, severity and spacing

Calcium citrate and Tetracycline antibiotic interact because calcium chelates tetracyclines in the intestinal lumen and reduces absorption. Take them 3 hours apart. Moderate risk.

Last reviewed: 2026-09-20Reviewed by: StackingRight clinical review

The interaction in detail

Summary of the Calcium citrate and Tetracycline antibiotic interaction
PairCalcium citrate and Tetracycline antibiotic
TypeNutrient–drug interaction
SeverityModerate
Required spacing3 hours minimum
OnsetAt the time of dosing

Mechanism

Calcium chelates tetracyclines in the intestinal lumen and reduces absorption.

What to do

Separate calcium from tetracycline by at least 2 hours.

Citationhttps://pubmed.ncbi.nlm.nih.gov/20017486/

How to fit both into one day

Calcium citrate
middaywith food

Calcium absorbs better with food and in doses at or below 500 mg. Take it with vitamin D3, and separate it from iron, zinc and thyroid medication.

Putting Calcium citrate in the midday and Tetracycline antibiotic in the evening satisfies the 3-hour separation without disrupting either one's absorption window.

Calcium citrate and Tetracycline antibiotic: common questions