Yarai › Conflict library › Niacinamide and vitamin C

Can you use niacinamide and vitamin C together?

Not a conflict

Yes. This pair is fine together, and Yarai deliberately does not flag it.

Not a conflict. Modern formulations combine them routinely and the pair is well tolerated. We shipped this as a rule, found the evidence did not hold, and removed it.

This is the single most repeated piece of skincare misinformation on the internet, and it is worth saying plainly: you can use them together. The two are combined in finished products by formulators who know exactly what they are doing. We are not neutral observers here, because Yarai shipped this as a conflict rule and then deleted it once we went back to the source.

What Yarai records for this pair

StatusNot a conflict. No rule exists in the engine for this pair.
HistoryShipped as rule 4, then removed once the evidence was reassessed.
BasisReassessment of the 1960s unstabilized-ascorbic-acid literature

Why we don't flag it

Where the claim came from: A 1960s study using pure unstabilized ascorbic acid at extreme temperatures, conditions that do not resemble a finished cosmetic formulation.

Most ingredient apps grow their conflict list forever, because adding a warning feels responsible and removing one feels risky. A rule that turns out to be wrong is worse than no rule: it sends you rearranging a routine that was already fine. Yarai's list is shorter on purpose, and what we removed is written down in the same file as what we kept.

What to do

  1. Use them together if you want to. Same routine, same layer order as any two serums, thinnest first.
  2. If you prefer them apart, that is a preference rather than a precaution, and nothing is going wrong either way.
  3. Judge by your own skin. Some people find high-strength ascorbic acid stinging on its own, which is about that product rather than about niacinamide.
  4. Ignore any app or article that flags this pair. It tells you something about their sourcing.

Related questions

Where did the myth come from?

A 1960s study using pure unstabilized ascorbic acid held at extreme temperatures, conditions that do not resemble a finished cosmetic formulation. The finding got repeated for decades without anyone revisiting the conditions it required.

Why did Yarai have this rule and then remove it?

Because we checked. It was rule 4 in our engine, it did not survive review, and it is now recorded in the same file as a pair we deliberately do not flag, so it cannot quietly reappear. A conflict list that only ever grows is not being maintained, it is being padded.

What about niacinamide with exfoliating acids?

Also fine. There are no niacinamide pairwise rules in Yarai's engine at all.

One pair is the easy part

Answering a single question like this one is straightforward. The harder question is the one you actually have: not whether these two work together, but whether the seven things on your shelf work together. Conflicts compound. Two moderate ones in the same evening are not two separate problems, they're one irritated face, and no single-pair answer anywhere on the internet can tell you that.

Yarai scans your products, builds them into an AM and PM routine, and checks every product against every other one, using these same graded rules with the same sources attached. You get the whole picture rather than one pair at a time.

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More pairs: Retinol and glycolic acid, Retinol and salicylic acid, Retinol and lactic acid. Or see the full conflict library.