Drug interactions
Calcium carbonate + Doxycycline
Severity: Moderate
Calcium carbonate and Doxycycline: moderate interaction.
Last updated
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.
Summary
Calcium carbonate can reduce doxycycline absorption, risking subtherapeutic antibiotic levels. The effect is generally less pronounced than with tetracycline but is still relevant.
What this interaction means in plain words
Calcium carbonate and Doxycycline can affect each other. The combination is often manageable, but it may need a change of dose, a change of timing, or extra checks while both are taken.
Calcium carbonate belongs to Gastrointestinal Tract; Doxycycline belongs to Anti Bacterial.
Why it happens
Calcium ions chelate doxycycline in the gut, forming poorly absorbed complexes, and raised gastric pH may further reduce absorption.
What to do
Take doxycycline at least 2 hours before or 4 hours after calcium carbonate.
What to ask your pharmacist
- Should I take them at different times of day?
- Does the dose of either medicine need to change?
- Is there anything I should avoid, such as alcohol or certain foods, while on both?
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Other interactions of Calcium carbonate
Other interactions of Doxycycline
- Acitretin + Doxycycline Contraindicated
- Aminolevulinic acid + Doxycycline Major
- Cholera vaccine + Doxycycline Major
- Doxycycline + Isotretinoin Major
- Doxycycline + Methoxyflurane Major
- Doxycycline + Microbiota Major
Frequently asked questions
Can I take Calcium carbonate with Doxycycline?
MediHelp rates the interaction as moderate. Calcium carbonate and Doxycycline can affect each other. The combination is often manageable, but it may need a change of dose, a change of timing, or extra checks while both are taken. Calcium carbonate can reduce doxycycline absorption, risking subtherapeutic antibiotic levels. The effect is generally less pronounced than with tetracycline but is still relevant.
How serious is the interaction between Calcium carbonate and Doxycycline?
MediHelp rates it moderate, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Take doxycycline at least 2 hours before or 4 hours after calcium carbonate.
What other medicines interact with Calcium carbonate?
MediHelp also lists interactions of Calcium carbonate with, for example, Acalabrutinib, Alendronate, Amlodipine-hydrochlorothiazide-valsartan. The full list is on the Calcium carbonate page.
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