Is Vitamin C (High Dose ≥1000mg/day) Safe with Calcitriol (Active Vitamin D)?
Free · No account · based on published sources including NIH ODS, FDA drug labels, and peer-reviewed literature
Limit vitamin C supplementation to dietary sources or doses below 200mg/day when taking calcitriol. Have 24-hour urine oxalate and calcium measured if high-dose vitamin C use is suspected. Report any flank pain or blood in urine immediately.
Why this interaction occurs
Calcitriol is prescribed in CKD to manage secondary hyperparathyroidism and requires careful calcium-phosphate balance. High-dose vitamin C increases urinary oxalate excretion, and when combined with the calcitriol-mediated increase in calcium absorption, the risk of calcium oxalate supersaturation in the renal collecting system increases significantly, potentially leading to nephrolithiasis or tubular injury in already-compromised kidneys.
Evidence
Evidence level: moderate.
Reported safety data
The FDA’s adverse event reporting system (FAERS) has received 3,340,197 reports mentioning Calcitriol (Active Vitamin D). This reflects reported cases involving the medication in general — not confirmed causation, and not specific to the Calcitriol (Active Vitamin D) + 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 Vitamin C (High Dose ≥1000mg/day) interactions → · All Calcitriol (Active Vitamin D) interactions →
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Educational only — not medical advice.
Always confirm with your doctor or pharmacist.