Polydeoxyribonucleotide. That is the whole word, and it is not a marketing term.

PDRN is short for polydeoxyribonucleotide. In plain English: fragments of DNA. In skincare it is usually taken from salmon, which is where the “salmon DNA” headlines come from.

Ours is from salmon. So it isn't vegan.

Here is the part that matters and that almost nobody mentions. PDRN is not simply the name of a substance — it describes DNA fragments within a particular size range. The word is a specification.

Our label says Sodium DNA, which is the broader name. We do not have the fragment length of ours confirmed in writing. So when we use the word PDRN, we are using the word this whole category uses — not a measurement we can hand you. You would have worked that out eventually. I would rather you read it here first.

There is a vegan version, made by fermenting bacteria instead of taking it from fish. It is not the same material — shorter fragments, a different organism — though it carries the same name on an ingredient list, Sodium DNA, so a label will not tell you which one you are holding. One published paper puts the two side by side and the fermented one comes out ahead, in test tubes and cell culture. Nobody has compared the two on human skin, and two of that paper's authors work for the companies that sell the fermented version. Ours is from salmon. If that ever changes, it goes on this page first.

1%. Printed, on every page we have.

Most brands in this category will not tell you theirs. That is legal, and it is worth understanding why. An ingredient list has to be ordered by concentration, but it does not have to carry a single number. So a spectacular-sounding ingredient can be present in a trace amount and every word on the box stays technically true.

Ours is 1%. Whether 1% impresses you is genuinely yours to decide — I would just rather you got to decide it.

Ask the last brand you bought from for their number. See what comes back.

Nearly all of it is injections, not serums.

Most of what's known about PDRN comes from injections, not from serums.

Applied to skin, the published human work is three studies and 74 people in total. One of the three used peony DNA rather than salmon, so it isn't about our raw material at all. Two of the three came from the same group of authors. Every one of them was run by people who sell the ingredient or sell a product made from it. We are counting them here because we would rather you got the real number from us than found it somewhere else — not because three is a lot. Three small studies with no outside group repeating them is still a thin file, and we are not going to build a promise on it.

Injected and applied are not the same question. When a doctor puts something underneath the skin, the skin is no longer in the way. A bottle on your bathroom shelf has to get past it first.

And one piece of honesty that cuts in our favor, which is exactly why I want to be careful with it: the one published this July did measure the ingredient moving into skin rather than just sitting on top of it — a few percent, into the outer living layer of the skin, in a small pilot on human forearms. The authors say themselves that their method cannot fully tell their ingredient apart from the DNA your own skin already contains. One paper. One industry group. A preparation with a stated fragment size, which ours does not have. That is what the file holds, and I am not going to dress it up as anything else.

The ingredient with the famous name is not the ingredient with the evidence.

Our niacinamide is at 2%. That's the lower of the two levels tested in the published split-face work on the appearance of facial spots — 2% and 5%. We're telling you where we sit on that scale. We're not telling you what it will do for your face.

Niacinamide is one of the few ingredients in this category where somebody actually tested two different amounts and published the difference. Most ingredients on most labels have never had that done. That's why we're willing to print our number next to it.

PDRN is the word on the front of this entire category. Niacinamide is the one somebody actually measured twice and published. We would rather tell you that ourselves than let the flashier word quietly do the work.

The part of this bottle that needs no asterisk.

Glycerin at 5%, plus hyaluronic acid and squalane. That part holds water at the surface of your skin and softens it. It's a moisturizing claim, and it's the one thing in this bottle we can say without an asterisk.

The FDA itself describes moisturizing as a cosmetic claim. It is the plainest, best-understood ground in this whole business, and it is where we are standing.

The peptides — including the part that does us no favors.

Six peptides, 3% between them. Two of the six have peer-reviewed human data behind them. Four don't — what exists for those comes from the companies that sell them. We're printing that too.

Which is why we do not put them at the front of anything. They are on the list below with their amounts, like everything else, and you can weigh that up yourself.

Every ingredient, with its amount.

Fragrance — none. SPF — none. The two colorants are printed in red because that is the line most likely to matter to you, not because it helps us. Patch test on your inner arm, twenty-four hours, before it goes near your face.