GHK-Cu peptide skincare claims: what TikTok gets wrong

What did @dermguru actually say?

The creator laid out a two-part routine: morning starts with a gentle cleanser, vitamin C, snail mucin, niacinamide, moisturizer, and sunscreen. Evening runs through a cleansing balm, water-based cleanser, retinoid, peptides, eye cream, hyaluronic acid, and moisturizer. That is the entire claim. No dosages, no brand names, just an ordered ingredient list delivered in under 30 seconds.

The framing is a dermatologist teaching you the correct sequence. That carries authority, and with 3.6 million views, a lot of people are taking notes. So the sequence actually matters here, and a few of the calls deserve scrutiny.

Does the science back this up?

Mostly, but with some real problems hiding in that evening line-up. The morning stack is largely defensible. The evening ordering, specifically putting hyaluronic acid after a moisturizer, contradicts the basic logic of layering thin-to-thick and conflicts with how HA actually functions.

Vitamin C in the morning is well-supported. A 2017 study by Pullar, Carr, and Vissers in Nutrients confirmed topical L-ascorbic acid stabilizes under UV exposure better than once believed and contributes to photoprotection alongside sunscreen. Niacinamide is one of the more rigorously tested topical actives, with Bissett et al. (2005, International Journal of Cosmetic Science) showing meaningful reductions in hyperpigmentation and fine lines at 5% concentration. Retinoids at night are textbook-correct and supported by decades of evidence going back to Kligman's original tretinoin work in the 1980s.

Peptides are where things get more complicated. GHK-Cu, for example, has shown some dermal remodeling activity in vitro and in small clinical trials (Pickart and Margolina, 2018, Symmetry), but the topical bioavailability data is inconsistent. The creator does not specify which peptides, which is a significant omission when the word carries very different meanings across product categories.

What did they get wrong (or right)?

The sequencing error is the biggest issue. Listing hyaluronic acid after moisturizer in the evening routine is backwards. Hyaluronic acid works by drawing water into the stratum corneum, but it needs to be applied to damp skin and then sealed in. Applying it after a moisturizer means it sits on top of an occlusive layer and cannot do its job. This is not a minor quibble. It is the kind of mistake that makes an expensive product functionally useless.

The morning combination of vitamin C followed immediately by snail mucin is also worth questioning. Snail mucin is slightly acidic and contains proteins that may reduce the stability of ascorbic acid formulations, though the research here is not definitive. A cautious approach would be to wait a few minutes between the two.

What they got right: double cleansing in the evening is well-supported for removing sunscreen and oil-based debris without stripping the barrier, as noted by Ananthapadmanabhan et al. (2004, Dermatitis). Retinoids at night, not morning, is correct. Sunscreen as the final morning step is correct.

What should you actually know?

Routine order is not arbitrary. The general principle is water-based and low-viscosity products first, heavier occlusives last. That means hyaluronic acid belongs before your moisturizer, not after it, regardless of what a 25-second TikTok suggests.

The peptides recommendation is vague in a way that matters. Topical peptides like Matrixyl (palmitoyl pentapeptide-4) and GHK-Cu have different mechanisms and different evidence bases. Matrixyl has some of the stronger topical data, including a double-blind trial by Robinson et al. (2005, International Journal of Cosmetic Science) showing wrinkle depth reduction. Lumping all peptides together as an evening step is the kind of shorthand that sells products without informing decisions.

If you are on a prescription retinoid, the question of what goes on before and after it matters clinically. Applying a heavy moisturizer before tretinoin, for instance, can reduce absorption and efficacy. That nuance is completely absent here. For anything beyond an OTC retinol, talk to a licensed provider rather than reverse-engineering a routine from a viral video.

• Apply hyaluronic acid to damp skin before moisturizer, not after it.
• Vitamin C and niacinamide can be used together despite older claims of incompatibility, but give vitamin C a few minutes to absorb first.
• Not all peptides are the same. Ask which peptide a product contains before assuming it matches the research.