What kind of interaction is it?

Caution: an interaction that may reduce efficacy or raise side-effect risk and warrants monitoring.

Is this interaction backed by published research?

Yes. NutriStack lists 2 citation rows for the Losartan/Hydrochlorothiazide + Vitamin D3 pair, each linking to PubMed by PMID where available. Full sourcing methodology at https://nutristackapp.com/methodology/interactions.

Supplement × Prescription·a caution·Moderate evidence

Losartan/Hydrochlorothiazide + Vitamin D3

Q: Can I take Losartan/Hydrochlorothiazide and Vitamin D3 together?

Possibly, but with caution. Losartan/Hydrochlorothiazide and Vitamin D3 have a documented caution-tier interaction. Vitamin D3 increases intestinal calcium absorption. Combined with hydrochlorothiazide's calcium-sparing effect on the kidney, high-dose vitamin D can elevate serum calcium and precipitate hypercalcemia, particularly when calcium supplements are also used. The risk is dose-dependent and greater in patients with hyperparathyroidism or reduced renal function.

Q: How does this affect a NutriStack Stack Score?

-5 to your Stack Score per scored caution row.

Caution Moderate evidence

Vitamin D3 increases intestinal calcium absorption. Combined with hydrochlorothiazide's calcium-sparing effect on the kidney, high-dose vitamin D can elevate serum calcium and precipitate hypercalcemia, particularly when calcium supplements are also used. The risk is dose-dependent and greater in patients with hyperparathyroidism or reduced renal function.

Supplement × Prescription

Open the interaction checker → Read the methodology

From the database

What the row says.

Every entry follows the same shape: what is happening, the mechanism, and the recommendation.

Substances

Losartan/Hydrochlorothiazide and Vitamin D3

Pair type

Caution

Evidence

Moderate

Source citations

Scope

Supplement × Prescription

Last verified

June 4, 2026

CautionModerate evidence

What is happening. Vitamin D3 increases intestinal calcium absorption. Combined with hydrochlorothiazide's calcium-sparing effect on the kidney, high-dose vitamin D can elevate serum calcium and precipitate hypercalcemia, particularly when calcium supplements are also used. The risk is dose-dependent and greater in patients with hyperparathyroidism or reduced renal function.

Mechanism. Vitamin D upregulates intestinal calcium absorption while hydrochlorothiazide reduces renal calcium excretion; the two effects together raise serum calcium.

Recommendation. Standard maintenance vitamin D doses are generally acceptable, but avoid high-dose vitamin D alongside this thiazide-containing combination without monitoring serum calcium, especially if calcium supplements are co-administered. Watch for symptoms of hypercalcemia.

Stack Score

How it moves the number.

Effect on the composite score

If both Losartan/Hydrochlorothiazide 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 at /methodology/stack-score.

Sources

Sources, by evidence tier.

Every claim on this page is cited. PMIDs link straight to PubMed.

Reference material

1Drinka PJ, Nolten WE. Hazards of treating osteoporosis and hypertension concurrently with calcium, vitamin D, and distal diuretics. J Am Geriatr Soc. 1984.Needs sourceNo link
2Crowe FL, et al. Plasma concentrations of 25-hydroxyvitamin D and risk of hypercalcemia. Postgrad Med J. 2011.Needs sourceNo link

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