NutriStack
Calcium and Digoxin, a caution.
Large or repeated calcium supplement doses can cause hypercalcemia in susceptible people, particularly with kidney disease, dehydration, thiazide use, or concurrent vitamin D. Hypercalcemia can increase the heart's sensitivity to digoxin and may contribute to conduction problems or arrhythmias. Routine dietary calcium is not the concern; high-dose supplementation and calcium-alkali syndrome are.
One pair, every claim cited. The two substances, the type, the mechanism, the recommendation, and the primary literature.
Same shape as the other 1,729 pairs in the public database.
From the interaction database
What the row says.
Every entry follows the same shape: what is happening, the mechanism, the recommendation, and the primary literature.
At a glance
- Pair type
- Caution
- Evidence (highest tier)
- Moderate
- Source citations
- 3 sources
- Stack Score effect
- −5 to your Stack Score (per scored caution row).
- Scope
- Supplement × Prescription
- Last verified
- May 30, 2026
Caution · Moderate evidence
Caution
What is happening. Large or repeated calcium supplement doses can cause hypercalcemia in susceptible people, particularly with kidney disease, dehydration, thiazide use, or concurrent vitamin D. Hypercalcemia can increase the heart's sensitivity to digoxin and may contribute to conduction problems or arrhythmias. Routine dietary calcium is not the concern; high-dose supplementation and calcium-alkali syndrome are.
Mechanism. Calcium excess can increase extracellular calcium and promote intracellular calcium overload in cardiac tissue. Digoxin inhibits Na+/K+-ATPase, indirectly increasing intracellular calcium; hypercalcemia can amplify this electrophysiologic vulnerability.
Recommendation. Do not take high-dose calcium supplements while on digoxin unless your clinician is monitoring calcium and kidney function. Stay within the prescribed daily elemental calcium target and avoid stacking multiple calcium-containing products. Seek urgent care for fainting, new irregular heartbeat, severe weakness, confusion, or persistent vomiting.
Sources (3)
- Vella A, Gerber TC, Hayes DL, Reeder GS. Digoxin, hypercalcaemia, and cardiac conduction. Postgrad Med J. 1999;75(887):554-556. PMID 10616693
- Picolos MK, Orlander PR. Calcium carbonate toxicity: the updated milk-alkali syndrome; report of 3 cases and review of the literature. Endocr Pract. 2005;11(4):272-280. PMID 16006300
- Walker MD, Shane E. Hypercalcemia: A Review. JAMA. 2022;328(16):1624-1636. PMID 36282253
Stack Score
How this pair moves the number.
Effect on the composite score
If both Calcium and Digoxin are in the same stack, this pair applies −5 to your Stack Score (per scored caution row).
The full algorithm, the clamping rules, and four worked stacks are documented at /methodology/stack-score.
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