Is Calcium Safe with Hydrochlorothiazide?
Free · No account · based on published sources including NIH ODS, FDA drug labels, and peer-reviewed literature
Unlike most diuretics, HCTZ reduces urinary calcium excretion, so avoid taking high-dose calcium supplements (>1200 mg/day) unless directed by your doctor. Excessive calcium combined with HCTZ can contribute to hypercalcemia or kidney stones in susceptible individuals.
Why this interaction occurs
Thiazide diuretics uniquely stimulate calcium reabsorption in the distal convoluted tubule by increasing the electrochemical gradient for calcium entry. This distinguishes them from loop diuretics which promote calciuresis. While this can be therapeutic in osteoporosis, supplemental calcium should be monitored to avoid hypercalcemia, particularly in patients with primary hyperparathyroidism or vitamin D toxicity.
Evidence
Evidence level: strong.
Reported safety data
The FDA’s adverse event reporting system (FAERS) has received 215,975 reports mentioning Hydrochlorothiazide. This reflects reported cases involving the medication in general — not confirmed causation, and not specific to the Hydrochlorothiazide + supplement combination on this page.
FAERS reports are voluntary and cannot prove that a drug caused an event. Do not use report counts to assess the safety of this specific drug-supplement pair.
Frequently asked questions
Related interactions
All Calcium interactions → · All Hydrochlorothiazide interactions →
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Educational only — not medical advice.
Always confirm with your doctor or pharmacist.