The Ingredient Files
Peptides, and what they are actually signalling.
Short chains of amino acids, chosen for what they do inside a formula rather than for how they read on a box. Here is what the published work actually examined, what it did not, and why peptides sit in four of our seven products.
500
The dalton figure above which compounds struggle to cross intact skin at all
12
Weeks, roughly, over which published peptide studies run, rather than days
4
PureNeem formulas that carry peptides, out of seven in the range
Short chains, doing a specific job.
Peptides are short chains of amino acids. Longer chains of the same building blocks form the structural proteins in skin, including collagen, elastin and keratin, and that relationship is where the whole reputation comes from.
Applied topically they behave as signalling ingredients. They resemble fragments that skin already recognises, and formulators use them on exactly that basis, to support the look of smoother, firmer looking skin rather than to sit on the surface as an occlusive.
Size is a large part of why they are useful at all. There is a long standing rule of thumb in topical formulation that compounds much above five hundred daltons struggle to move through intact skin (Bos and Meinardi, 2000). Peptides are designed around that constraint. Whole proteins, including the collagen printed on a great many labels, are not.
Encouraging, and worth reading precisely.
Palmitoyl pentapeptide-4 has been examined in a double blind randomised controlled trial looking at the appearance of photoaged skin (Watson et al., 2009). Acetyl hexapeptide-8 has its own literature concerned with the look of expression lines (Blanes-Mira et al., 2002). Reviews have since mapped the main families and what each has and has not been shown to do (Schagen, 2017).
What that means in an actual routine is worth stating plainly, because almost nobody does. Peptide outcomes are visible rather than dramatic, gradual rather than immediate, and measured across months rather than weeks. The studies run for twelve weeks or more for a reason.
They are also cumulative and reversible. Stop using them and the look drifts back. That is true of most of skincare and it is unfashionable to say so, but it is the honest frame for anyone deciding whether a peptide formula is worth the shelf space.
They get along with everything.
Peptides are unusually easy to build a formula around. They are well tolerated across skin types, they carry no scent or colour of their own, and they sit comfortably beside niacinamide, ceramides and retinoids rather than competing with them for room.
That makes them useful in two opposite situations. For skin that cannot tolerate a stronger resurfacing active, peptides are a gentle route to the look of firmness. Inside a formula that already carries a strong active, they add a second line of work without adding irritation, which is why they appear alongside retinol in our night cream and alongside snail secretion filtrate in our day cream.
Stabilisation has improved considerably as well. A peptide in a well built modern formula is a good deal more reliable than one from a decade ago, which is part of why the same two or three names now turn up across an entire category.
Chosen for what they do, not for how they sound.
Not all peptides are the same thing.
Peptide is a category, not an ingredient, and the differences between the families are larger than the similarities. This is the map.
| Family | Example | What formulators use it for |
|---|---|---|
| Signal peptides | Palmitoyl tripeptide-1 | The look of firmer, smoother skin over months |
| Signal peptides | Tetrapeptide-7 and Tetrapeptide-38 | Supporting a calm, even looking surface |
| Expression line peptides | Acetyl hexapeptide-8 | Softening the look of movement lines |
| Carrier peptides | Copper tripeptide-1 | Carrying trace minerals through a formula |
We use the first two rows. Palmitoyl Tripeptide-1 and Tetrapeptide-7 are the base pairing across our range, with Tetrapeptide-38 added in the night cream and Tetrapeptide-30 in the radiance serum. We do not use expression line peptides, because we would rather a formula worked on the look of the skin itself than on the way you move your face.
Four products, four different reasons.
Peptides are also in Amra Nourishing Body Balm, where Palmitoyl Tripeptide-1 and Tetrapeptide-7 sit with ceramides and panthenol so body skin gets the same care as face skin, and in Luminara C Radiance Serum, where Tetrapeptide-30 works underneath the tone actives. These two are where they do the most visible work.
Paired with retinol and ceramides, so the barrier has support while the retinol does the assertive work overnight. This is the pairing that makes a retinol formula wearable rather than something you push through.
With snail secretion filtrate, snow mushroom and centella, supporting the look of plump, comfortable skin underneath a silky, clean finish that layers without pilling.
A practical note on pairing
Peptides and retinol belong in the same routine, which is exactly why they are in the same jar in Rejuvence. The peptides and ceramides support the barrier while the retinol works, and that is the thing most first time retinol users are missing.
If you are starting from nothing, our retinol guide sets out the four week ramp that prevents most of the dryness people give up over in the first fortnight.
Common questions
Peptides, answered plainly.
What do peptides actually do for skin?
They act as signalling ingredients, resembling fragments the skin already recognises. In cosmetic terms that translates to supporting the look of firmer, smoother skin, gradually, alongside everything else in the formula.
How long do peptides take to work?
Longer than most people are told. Published studies typically run twelve weeks or more, and the changes described are visible rather than dramatic. Anything promising a shorter timeline is describing hydration, not peptides.
Can you use peptides with retinol?
Yes, and it is one of the better pairings available. They work on different pathways and do not cancel each other out. In a well built formula they sit in the same product, which is simpler than layering two.
Are peptides better than retinol?
They are not competitors. Retinol is the more assertive ingredient with the larger evidence base and the higher tolerance cost. Peptides are gentler, slower and easier to live with. Most good routines end up with both.
Do peptides work in a wash off product?
Not usefully. Peptides need contact time, so they belong in a serum, cream or balm that stays on the skin. A peptide named on a cleanser is doing more for the label than for your face, which is why ours are not in one.
References
- Blanes-Mira, C., Clemente, J., Jodas, G., Gil, A., Fernandez-Ballester, G., Ponsati, B., and Ferrer-Montiel, A. (2002). A synthetic hexapeptide with antiwrinkle activity. International Journal of Cosmetic Science, 24(5), 303 to 310.
- Bos, J. D., and Meinardi, M. M. (2000). The 500 Dalton rule for the skin penetration of chemical compounds and drugs. Experimental Dermatology, 9(3), 165 to 169.
- Schagen, S. K. (2017). Topical peptide applications with effective anti-ageing results. Cosmetics, 4(2), 16.
- Watson, R. E. B., Ogden, S., Cotterell, L. F., Bowden, J. J., and Griffiths, C. E. M. (2009). A cosmetic antiaging product improves photoaged skin: A double blind, randomised controlled trial. British Journal of Dermatology, 161(2), 419 to 426.
Peptides in Action: Explore Our Formulations
