Drug interactions
Calcium + Diltiazem
Severity: Moderate
Calcium and Diltiazem: 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
Intravenous calcium can reverse the hemodynamic and conduction effects of diltiazem, and calcium salts are used as an antidote in calcium channel blocker overdose. Oral calcium at usual supplement doses is unlikely to blunt the antihypertensive effect meaningfully, but IV doses may reduce efficacy.
What this interaction means in plain words
Calcium and Diltiazem 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; Diltiazem belongs to Cardiovascular.
Why it happens
Increased extracellular calcium opposes L-type calcium channel blockade by diltiazem (pharmacodynamic antagonism).
What to do
Monitor blood pressure, heart rate and ECG when IV calcium is given to a patient on diltiazem, and avoid unnecessary IV calcium unless treating toxicity or hypocalcemia. Routine oral calcium supplements generally need no adjustment.
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 Diltiazem
- Diltiazem + Flibanserin Contraindicated
- Diltiazem + Ivabradine Contraindicated
- Diltiazem + Lomitapide Contraindicated
- Diltiazem + Lonafarnib Contraindicated
- Acebutolol + Diltiazem Major
- Alfentanil + Diltiazem Major
Frequently asked questions
Can I take Calcium with Diltiazem?
MediHelp rates the interaction as moderate. Calcium and Diltiazem 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. Intravenous calcium can reverse the hemodynamic and conduction effects of diltiazem, and calcium salts are used as an antidote in calcium channel blocker overdose. Oral calcium at usual supplement doses is unlikely to blunt the antihypertensive effect meaningfully, but IV doses may reduce efficacy.
How serious is the interaction between Calcium and Diltiazem?
MediHelp rates it moderate, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Monitor blood pressure, heart rate and ECG when IV calcium is given to a patient on diltiazem, and avoid unnecessary IV calcium unless treating toxicity or hypocalcemia. Routine oral calcium supplements generally need no adjustment.
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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