Can You Take Vitamin C and Vitamin D3 Together?

Dose or timing may matter

The short answer

Vitamin D3 increases calcium absorption leading to higher urinary calcium, while high-dose vitamin C generates oxalate. Together they may synergistically raise calcium oxalate kidney stone risk.

How to arrange timing

Keep vitamin C under 1,000 mg/day and vitamin D3 at standard doses (1,000-2,000 IU/day). Monitor if prone to kidney stones.

Reference

Reference noted for this combination: Thomas LD et al. JAMA Intern Med. 2013;173(5):386-388; Gallagher JC et al. Ann Intern Med. 2014;160(1):11-17

Important context

Whether supplements suit you together also depends on dose, product formulation, health conditions, and medication use. Ask a doctor or pharmacist first if you take medication, are pregnant or breastfeeding, or have a chronic condition.