Drug interactions
Calcium carbonate + Rifampin
Severity: Moderate
Calcium carbonate and Rifampin: 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
Antacids taken with rifampin can lower its absorption and blood concentrations, which may reduce its effectiveness in treating infections such as tuberculosis. The reduction is modest but undesirable when treating serious infections.
What this interaction means in plain words
Calcium carbonate and Rifampin 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.
Why it happens
Antacids reduce gastrointestinal absorption of rifampin, possibly through adsorption or altered gastric conditions.
What to do
Give rifampin at least 1 hour before the antacid, preferably on an empty stomach, and monitor clinical response.
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
Frequently asked questions
Can I take Calcium carbonate with Rifampin?
MediHelp rates the interaction as moderate. Calcium carbonate and Rifampin 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. Antacids taken with rifampin can lower its absorption and blood concentrations, which may reduce its effectiveness in treating infections such as tuberculosis. The reduction is modest but undesirable when treating serious infections.
How serious is the interaction between Calcium carbonate and Rifampin?
MediHelp rates it moderate, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Give rifampin at least 1 hour before the antacid, preferably on an empty stomach, and monitor clinical response.
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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