Clear serum droplets of many different sizes suspended against pale blue

The Best Peptides for Skin: How to Tell Which One You're Actually Buying

Every good cream says peptides. She finally read the back of hers — and found the number that tells you which one you're actually paying for.

Your esthetician said the new serum has peptides, and you nodded, because everyone nods. It is a word that sounds like it settled something.

It settles about as much as gluten-free on a bag of almonds.

Which would be fine, except that you have been nodding at that word for about six years. And paying for it. Three things on your counter say it — the serum, the eye cream, and the one you took home from a facial — and one Sunday, for no particular reason, you turned all three over and read the backs.

What the Three Jars Had in Common

Not much. The forty-dollar serum had a peptide four links long. The ninety-dollar eye cream had one six links long. And the one from the facial, the one that cost more than the facial, had — after the water and the glycerin and a word you had to look up — a peptide four links long. The same one as the serum.

You had paid three prices for two ingredients. The word on the front had covered for all of it.

Peptides on the front of a box is not information. It is a category.

The Number Is in the Name

You could read them because the length is hiding in the name, in a language you already half speak. Tri is three, like triple. Tetra is four. Penta is five. Hexa is six. And when a name reaches oligo or poly, the counting has gone past the point of counting.

That number is most of the price. The short ones a brand can buy by the bucket. The long ones it has to explain to its accountant. Both get the same word on the front, in the same confident font, said out loud in the same confident voice.

Woman in a towel turban studying her skin closely in the bathroom mirror

The Long Peptides Your Body Already Makes

That was the other thing you found. None of your three went past six. And the long ones exist — fifty links, a hundred, a hundred and forty. Your body has been making them since long before you had a skincare routine, free of charge, without being asked. They are called growth factors, and the science that found them won the 1986 Nobel Prize.

Everything shorter came afterward. Copies, in effect — cheaper to make, sturdier in a jar, far easier to fit on a label. We wrote about why so few creams carry the originals, and the reason is duller than a conspiracy: they cost a fortune and they are difficult to keep alive.

So your three jars were not lying. They were just all short, and using the long word.

The Number Everyone Quotes

Somewhere in the reading you also met the figure. 27% fewer wrinkles in thirty days. It belongs to Argireline — the six-link one, which is a good ingredient, good enough that it is in both of our creams — and it has been reprinted for twenty years.

It came from a study of ten women.

The peptide was never the problem. The problem is that an entire industry found one small number in 2002 and has been quoting it at you ever since, with the same face your friend makes when she is repeating something she read once. So when a brand hands you a number, the useful question is how many women it came from. That is worth knowing before you spend two hundred dollars on the strength of it.

What the Long Ones Actually Do

Ours, then — since we have opinions about everyone else's numbers.

The honest size of it. The biggest review of growth factors so far pooled 33 studies and 1,180 people. Investigators put the improvement in skin texture at under 50%, and in fine lines at under 35%. Real. Visible. Worth it to a great many women — and nothing like the way this category talks. Most of the flattering studies were paid for by the people selling the ingredient. We have not run one either.

We would rather you hear that from us than find it on your own later.

The Next Facial

She says the new serum has peptides. And you say — pleasantly, because she is lovely and none of this is her fault — which one?

She goes to check.

You have never once seen her go to check.

Keep this oneThe front of the box gives you the word. The ingredient list gives you the number, and the number is most of what you paid for. Tri, tetra, penta, hexa — and past that, the long ones. One second, any brand, any counter, for the rest of your life.

Which of Ours Has the Long Ones

If you go looking for them — and now you can — there are two of ours to choose between, both at medical-grade amounts, which is the number a front panel never has room for.

The SKINWIT Firming & Illuminating Eye Cream carries the short ones you already know — Matrixyl 3000 and Argireline, for expression lines — alongside EGF, and a gentle retinol.

SKINWIT THE EYE CREAM carries EGF and FGF — both of the long ones — with bakuchiol instead of a retinoid, for skin that would rather not negotiate.

Both come with the Empty-the-Bottle Guarantee: finish the jar, and if your skin disagrees, it's on us.

Sources. Blanes-Mira et al., International Journal of Cosmetic Science 2002 (acetyl hexapeptide, n=10, 30 days) · Quinlan, Ghanem & Hassan, Journal of Cosmetic Dermatology 2023 (systematic review of topical growth factors: 33 studies, 1,180 participants) · Pai, Bhandari & Shukla, Indian Journal of Dermatology, Venereology and Leprology 2017 (classification of cosmeceutical peptides) · The Nobel Prize in Physiology or Medicine 1986, awarded for the discovery of growth factors (NobelPrize.org).