GHK-Cu peptide for skin aging: what TikTok gets wrong

What did @drjennyliu actually say?

@drjennyliu laid out a full AM and PM anti-aging skincare routine using drugstore products, all priced to stay under $100. The morning lineup: a gentle cleanser, vitamin C serum, moisturizer, and SPF. The evening lineup: micellar water, optional double cleanse, a retinol-moisturizer combo (different picks for oily vs. dry skin), and a once or twice weekly swap to "lactic acid 10%" from The Ordinary as an exfoliant. She positioned retinol as "the OG anti-aging" ingredient, and the whole framing is that solid, evidence-based skincare doesn't require a dermatologist-priced product lineup.

There's nothing experimental here. No peptide injections, no prescription compounds. This is a consumer-facing OTC routine built around ingredients with actual clinical histories. That framing is worth taking seriously before picking it apart.

Does the science back this up?

Largely, yes. The core ingredients she recommends, retinol, vitamin C, SPF, and an AHA exfoliant, are among the most studied actives in dermatology. The evidence base is real, not influencer mythology.

Retinoids are the most clinically validated topical anti-aging ingredients in existence. Kafi et al. (2007, Archives of Dermatology) showed that low-concentration retinol applied over 24 weeks significantly improved fine lines and increased collagen production in older skin. Vitamin C (L-ascorbic acid) at concentrations above 10% has been shown to stimulate collagen synthesis and provide antioxidant protection against UV-induced oxidative stress (Pullar et al., 2017, Nutrients). Daily broad-spectrum SPF is not optional in any credible anti-aging conversation. Photoaging accounts for the majority of visible skin aging, and the landmark Weinstock et al. and Hughes et al. (2013, Annals of Internal Medicine) randomized trial showed that daily sunscreen use measurably slowed photoaging over 4.5 years. Lactic acid at 10% is a well-tolerated AHA with evidence for surface exfoliation and modest collagen stimulation (Smith, 1996, Journal of the American Academy of Dermatology).

What did they get wrong (or right)?

She got the fundamentals right. Where the routine gets slightly sloppy is in the detail layer, specifically the lack of guidance on retinol frequency and the vitamin C placement.

Retinol and vitamin C are both good ingredients. Using them without context, though, sets some viewers up for irritation. Vitamin C serums (especially L-ascorbic acid formulas) are most effective at low pH, which can increase skin sensitivity. Applying retinol the same night after a vitamin C serum used in the morning is generally fine, but she doesn't flag that retinol should be introduced slowly, typically two to three nights per week before building up, especially for beginners. Kligman and Kligman's foundational retinoid research consistently showed that barrier disruption is the primary side effect of rushing frequency. The lactic acid 10% substitution once or twice a week is a smart call for beginners, but using it the same week as frequent retinol without a buffer can tip sensitive skin into over-exfoliation. She never addresses this. That's not a minor omission for a 137K-view skincare tutorial.

What should you actually know?

The ingredient logic here is sound. SPF daily, retinol at night, vitamin C in the AM, and a gentle AHA weekly is a routine that dermatology literature supports. The under-$100 price point is achievable and the product categories she chose are reasonable.

A few real-world caveats worth knowing: Olay Retinol24 and Neutrogena Rapid Wrinkle Repair both use retinol rather than prescription tretinoin, which means they work through a slower conversion pathway and are less potent. That's not a knock, it means they're more tolerable, but expectations should match. For people with active acne, rosacea, or compromised barriers, some of these products need medical guidance before use, not a TikTok routine. And SPF should always be the last step in AM, applied after moisturizer, not skipped because "the dewy finish feels heavy." Elf's Halo Glow SPF has been independently tested and does provide broad-spectrum coverage, so that choice is defensible. One more note: lactic acid 10% from The Ordinary is a legitimate AHA exfoliant with a straightforward formula, but 10% is not beginner-light. New users should patch test and start once weekly.