Drug interactions
Calcium + Chlorthalidone
Severity: Moderate
Calcium and Chlorthalidone: 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
Thiazide-type diuretics reduce urinary calcium excretion, so combining chlorthalidone with calcium supplements can raise serum calcium. Hypercalcemia is more likely with high calcium doses, concurrent vitamin D, or renal impairment. Milk-alkali syndrome has been described with large calcium intake.
What this interaction means in plain words
Calcium and Chlorthalidone 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; Chlorthalidone belongs to Cardiovascular.
Why it happens
Thiazide-like diuretics enhance distal tubular calcium reabsorption, reducing renal calcium clearance.
What to do
Check serum calcium at baseline and periodically, especially in patients on high-dose calcium or vitamin D. Reduce the calcium dose if calcium rises.
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 Chlorthalidone
Frequently asked questions
Can I take Calcium with Chlorthalidone?
MediHelp rates the interaction as moderate. Calcium and Chlorthalidone 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. Thiazide-type diuretics reduce urinary calcium excretion, so combining chlorthalidone with calcium supplements can raise serum calcium. Hypercalcemia is more likely with high calcium doses, concurrent vitamin D, or renal impairment. Milk-alkali syndrome has been described with large calcium intake.
How serious is the interaction between Calcium and Chlorthalidone?
MediHelp rates it moderate, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Check serum calcium at baseline and periodically, especially in patients on high-dose calcium or vitamin D. Reduce the calcium dose if calcium rises.
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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