Peptide skincare

COSRX The 6 Peptide Skin Booster Serum

by COSRX · Value per millilitre

Ranked #5$25.00

150 mL of six peptides including copper tripeptide-1 and Argireline. The lowest cost per millilitre on our list by a wide margin.

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Our assessment

150 mL for the price most brands charge for 30, with copper tripeptide-1 and Argireline on the INCI list plus niacinamide and hyaluronic acid. The peptide concentrations are undisclosed and presumably modest at this dilution, which is why it ranks below the bottles above despite the headline ingredient overlap. As a generously sized hydrating serum with a real peptide presence, it has no peer at the price.

What the evidence supports

Cosmetic peptides are the best-credentialed corner of the anti-aging aisle, which is faint praise worth decoding: two ingredients carry real published support (palmitoyl pentapeptide-4 from a 12-week double-blind facial trial, and copper tripeptide-1/GHK-Cu from decades of wound-healing literature), while the rest run on supplier-sponsored testing. Expect modest fine-line and texture improvement over 8 to 12 weeks, not a procedural result, and read our peptides-in-skincare review for the full class-by-class grading.

Use, as reported in the trials

Peptide serums layer without conflict alongside retinoids, niacinamide and sunscreen, the better-evidenced backbone of any routine. The one documented caution: avoid applying copper peptides and strong ascorbic-acid (vitamin C) formulas in the same session, since copper can destabilize the vitamin; splitting them between morning and evening resolves it. Judge any peptide product at 12 weeks against a day-zero photo, because the published studies measured at 4 to 12 weeks and supplier claims of overnight change describe hydration, not structure.

Where it ranks