NutriStack
Calcium and Hydrochlorothiazide, a caution.
Hydrochlorothiazide reduces urinary calcium excretion and can raise serum calcium. Adding high-dose calcium supplements can increase the risk of hypercalcemia, especially in older adults or people with kidney disease, hyperparathyroidism, dehydration, or heavy calcium antacid use. Symptoms can include nausea, constipation, thirst, confusion, kidney injury, and rhythm problems when severe.
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
- Calcium and Hydrochlorothiazide
- 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. Hydrochlorothiazide reduces urinary calcium excretion and can raise serum calcium. Adding high-dose calcium supplements can increase the risk of hypercalcemia, especially in older adults or people with kidney disease, hyperparathyroidism, dehydration, or heavy calcium antacid use. Symptoms can include nausea, constipation, thirst, confusion, kidney injury, and rhythm problems when severe.
Mechanism. Thiazides increase distal tubular calcium reabsorption and lower urinary calcium loss. Calcium supplements increase calcium load, so the combination can exceed renal and hormonal buffering capacity in susceptible patients.
Recommendation. Avoid high-dose calcium supplementation while taking hydrochlorothiazide unless your prescriber recommends it. Keep total calcium intake within your goal range and ask for serum calcium monitoring if you use calcium daily, have kidney stones, or develop hypercalcemia symptoms.
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
- Desai HV, Gandhi K, Sharma M, Jennine M, Singh P, Brogan M. Thiazide-induced severe hypercalcemia: a case report and review of literature. Am J Ther. 2010;17(6):e234-e236. PMID 20068444
Stack Score
How this pair moves the number.
Effect on the composite score
If both Calcium and Hydrochlorothiazide 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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