Is Vitamin A Safe with Vitamin D3?
Free · No account · based on published sources including NIH ODS, FDA drug labels, and peer-reviewed literature
Avoid supplemental preformed Vitamin A (retinol) doses exceeding 1,500 mcg RAE (5,000 IU) daily when taking Vitamin D3. Prefer beta-carotene forms of Vitamin A if supplementation is needed. Have both vitamin levels monitored if taking both long-term.
Why this interaction occurs
Preformed Vitamin A (retinol) at high doses antagonizes Vitamin D3 receptor signaling by competing for shared retinoid X receptor (RXR) heterodimerization, reducing Vitamin D's ability to promote intestinal calcium absorption and bone mineralization. Epidemiological studies link high retinol intake with increased fracture risk and reduced bone mineral density, even at doses not traditionally considered toxic.
Evidence
Evidence level: strong.
Reported safety data
The FDA’s adverse event reporting system (FAERS) has received 708,274 reports mentioning Vitamin D3. This reflects reported cases involving the medication in general — not confirmed causation, and not specific to the Vitamin D3 + 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 A interactions → · All Vitamin D3 interactions →
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Educational only — not medical advice.
Always confirm with your doctor or pharmacist.