Drug interactions
Calcium + Oxytetracycline
Severity: Moderate
Calcium and Oxytetracycline: 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
Oral calcium markedly reduces the absorption of oxytetracycline, which can lead to subtherapeutic antibiotic levels and treatment failure. Dairy-type calcium sources and supplements both contribute.
What this interaction means in plain words
Calcium and Oxytetracycline 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 belongs to Gastrointestinal Tract; Oxytetracycline belongs to Anti Bacterial.
Why it happens
Calcium cations chelate oxytetracycline in the gut, forming non-absorbable complexes.
What to do
Take oxytetracycline at least 2 hours before or 4 hours after calcium products. Consider a different antibiotic if calcium cannot be withheld.
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
Other interactions of Oxytetracycline
- Isotretinoin + Oxytetracycline Contraindicated
- Aluminum hydroxide + Oxytetracycline Moderate
- Ampicillin-sulbactam + Oxytetracycline Moderate
- Ampicillin + Oxytetracycline Moderate
- Atracurium + Oxytetracycline Moderate
- Bismuth subsalicylate + Oxytetracycline Moderate
Frequently asked questions
Can I take Calcium with Oxytetracycline?
MediHelp rates the interaction as moderate. Calcium and Oxytetracycline 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. Oral calcium markedly reduces the absorption of oxytetracycline, which can lead to subtherapeutic antibiotic levels and treatment failure. Dairy-type calcium sources and supplements both contribute.
How serious is the interaction between Calcium and Oxytetracycline?
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 oxytetracycline at least 2 hours before or 4 hours after calcium products. Consider a different antibiotic if calcium cannot be withheld.
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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