10 peptides in this category. Click any to open its calculator.
Cosmetic peptides are studied almost entirely as topical ingredients at parts-per-million concentrations, and the trial data belong to creams and serums rather than to injections. Argireline's pivotal wrinkle figure came from an industry-funded study of ten people without a placebo, and the one independent split-face trial found no significant effect. GHK-Cu has the strongest controlled evidence in this group, and it too is topical. The calculators cover the injectable arithmetic where a research vial exists; the notes explain what the concentration figures really refer to. Two practical points follow from that. First, a concentration quoted as a percentage usually refers to a diluted commercial solution rather than to active peptide, and the two differ by around a thousandfold — the pivotal Matrixyl trial used 3 ppm, not 3 per cent. Second, molecular weight decides whether a topical peptide reaches anything at all: above roughly 500 daltons, skin penetration becomes the limiting step, and several popular ingredients sit well above it. The melanocortin compounds in this group are a separate matter again, with documented harms that have nothing to do with cosmetics.
