NutriStack
Chlorthalidone and Vitamin D3, a caution.
Chlorthalidone can increase serum calcium by lowering urinary calcium excretion, while Vitamin D3 increases intestinal calcium absorption. Usual Vitamin D3 replacement is often tolerated, but high-dose supplementation or combined calcium use can increase hypercalcemia risk. This matters most in kidney disease, hyperparathyroidism, granulomatous disease, or dehydration.
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
- Substances
- Chlorthalidone and Vitamin D3
- Pair type
- Caution
- Evidence (highest tier)
- Moderate
- Source citations
- 2 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. Chlorthalidone can increase serum calcium by lowering urinary calcium excretion, while Vitamin D3 increases intestinal calcium absorption. Usual Vitamin D3 replacement is often tolerated, but high-dose supplementation or combined calcium use can increase hypercalcemia risk. This matters most in kidney disease, hyperparathyroidism, granulomatous disease, or dehydration.
Mechanism. Chlorthalidone shares thiazide-like calcium-retaining effects in the distal nephron. Vitamin D3 increases calcium absorption, so the pathways can add together and raise serum calcium.
Recommendation. Use Vitamin D3 with a monitoring plan if you take chlorthalidone and need high-dose therapy. Ask about checking serum calcium after starting Vitamin D3, increasing the dose, or adding calcium.
Sources (2)
- Wermers RA, Kearns AE, Jenkins GD, Melton LJ 3rd. Incidence and clinical spectrum of thiazide-associated hypercalcemia. Am J Med. 2007;120(10):911.e9-911.e15. PMID 17904464
- Chandler PD, Scott JB, Drake BF, Ng K, Forman JP, Chan AT, et al. Risk of hypercalcemia in blacks taking hydrochlorothiazide and vitamin D. Am J Med. 2014;127(8):772-778. PMID 24657333
Stack Score
How this pair moves the number.
Effect on the composite score
If both Chlorthalidone and Vitamin D3 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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