Drug interactions
Calcium + Rifampin
Severity: Moderate
Calcium 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 such as calcium carbonate may lower rifampin absorption, which could reduce its antibacterial effect. This matters in tuberculosis treatment, where subtherapeutic levels risk treatment failure and resistance.
What this interaction means in plain words
Calcium 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
Reduced gastrointestinal absorption of rifampin when given with antacids.
What to do
Give rifampin at least 1 hour before calcium-containing antacids. Monitor clinical response in patients with serious infection.
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
- Calcium + Ceftriaxone Contraindicated
- Acalabrutinib + Calcium Moderate
- Alendronate + Calcium Moderate
- Atazanavir + Calcium Moderate
- Baloxavir marboxil + Calcium Moderate
- Bendroflumethiazide + Calcium Moderate
Frequently asked questions
Can I take Calcium with Rifampin?
MediHelp rates the interaction as moderate. Calcium 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 such as calcium carbonate may lower rifampin absorption, which could reduce its antibacterial effect. This matters in tuberculosis treatment, where subtherapeutic levels risk treatment failure and resistance.
How serious is the interaction between Calcium 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 calcium-containing antacids. Monitor clinical response in patients with serious infection.
What other medicines interact with Calcium?
MediHelp also lists interactions of Calcium with, for example, Ceftriaxone, Acalabrutinib, Alendronate. The full list is on the Calcium page.
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