Medik8 Liquid Peptides

Ingredient-list position is the one honest signal you have about peptide dosing, and this product passes that test better than any other here.

All ten peptides appear at positions 4 through 14 — before the hyaluronic acid, and far before the preservatives. Ingredients above 1% must be listed in descending order, so peptides listed after the preservatives are present in trace amounts. These are not.

The peptides are real, named technologies: Matrixyl 3000 and Matrixyl Synthe'6 (the most-studied collagen-signaling peptides), Argireline, a copper peptide, and several others.

If you have decided to buy a peptide serum, this is a well-constructed one.

Peptides are the most oversold category in skincare, and this is the honest picture.

A 2026 systematic review in Frontiers in Medicine pooled 19 randomized trials of peptides. Only two of them tested topical peptides — the rest tested oral collagen supplements. And the wrinkle benefit the review found was driven almost entirely by the oral studies, not the topical ones. Elasticity showed no meaningful effect at all.

There is also a physical problem. Peptides are large molecules, and the skin barrier is very good at keeping large molecules out. Independent reviews of the penetration data are blunt about it: most topical peptides concentrate in the outermost dead layer of skin and drop off sharply below that — nowhere near the depth where collagen is actually made.

And most of the foundational research comes from the companies that sell the peptides — Sederma, Lipotec — rather than from independent labs.

None of this means peptides do nothing. They are gentle, they are well tolerated, and there is a real argument for them in skin that cannot handle retinoids. But be clear on the comparison: retinoids have decades of large, independent, randomized evidence for wrinkles and photoaging. Peptides do not. Gentler, yes. Equally proven, no — not close.

The "30% peptide complex" claim is not what it sounds like. That almost certainly refers to a pre-blended delivery complex used at 30% of the formula — not 30% pure peptide, which would be extraordinary. Treat the number as marketing shorthand.

$62–$95 is a lot for a category where the evidence is this thin and mostly supplier-funded.

Two products with nearly the same name. "Liquid Peptides" and "Liquid Peptides Advanced MP" are different formulas at different prices. Check which you are buying.

No independent clinical trial on this formula — only generic ingredient-supplier data.

🧬 Peptide Complex — collagen-boosting

Formulation Notes

Palmitoylation is the trick behind most of these — attaching a fatty acid tail (the "palmitoyl" in palmitoyl tripeptide-1) to help a water-loving peptide cross an oil-loving skin barrier.

It helps. It does not solve the problem. The penetration data still shows most peptide staying in the upper layers, which is the central unresolved issue for the entire category — not a flaw specific to this product.