From the databaseWhat the row says.
Every entry follows the same shape: what is happening, the mechanism, and the recommendation.
Scope
Supplement × Prescription
Last verified
June 4, 2026
CautionEmerging evidence
What is happening. Very high-dose vitamin C can increase urinary oxalate burden, which is undesirable in patients needing renal dose adjustment for famciclovir.
Mechanism. This is a renal-risk context interaction rather than a direct famciclovir pharmacokinetic interaction.
Recommendation. Avoid vitamin C megadoses in kidney disease or dehydration; routine dietary vitamin C is not a concern.
Stack Score
How it moves the number.
Effect on the composite score
If both Famciclovir and Vitamin C 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.
SourcesSources, by evidence tier.
Every claim on this page is cited. PMIDs link straight to PubMed.
Reference material
1- 1Kidney stone and renal dosing safety reviews.Needs sourceNo link