Collagen Supplements for Skin: What the Trials Show and Who Funded Them

Direct answer: When you pool the trials, collagen supplements for skin show modest gains in hydration and elasticity over 8–12 weeks. But the best-designed and independently funded trials show no clear effect. A 2025 meta-analysis of 23 RCTs found that the benefit disappeared when the authors looked only at non-industry-funded or high-quality studies. Evidence: Mixed / contested.

Key takeaways

• Three meta-analyses pooled 19 to 26 randomized trials each, and all three found average improvements in skin hydration and elasticity with hydrolyzed collagen (Pu et al., 2023; de Miranda et al., 2021; Myung & Park, 2025).
• The most recent one split the trials by funding and quality. Studies without industry funding, and studies rated high quality, showed no significant effect on hydration, elasticity or wrinkles (Myung & Park, 2025).
• In most of the individual trials we review below, at least some authors came from collagen manufacturers or contract research firms.
• Collagen fragments such as Pro-Hyp do reach the blood after you swallow them (Iwai et al., 2005). The lab studies showing they act on skin cells used higher concentrations than were measured in blood (Shigemura et al., 2009).
• Trial doses ranged from 1,000 mg to 5 g a day. No study in our sources shows that more is better, and one pooled analysis found no significant difference between collagen sources for elasticity (Pu et al., 2023).

Why this guide starts with the disagreement

Most articles about collagen supplements for skin pick one of two lines: "the studies prove it works" or "it's all just digested protein." Neither fits the data. The trial record is large enough to take seriously, and it is also skewed enough that you shouldn't take it at face value.

So we put the tension up front. Below you'll find each major randomized trial with its sample size, duration, dose and funding. Then come the three meta-analyses, the absorption science, and the practical questions readers keep asking. This page is the hub for our Collagen & Oral Peptides pillar. If you're weighing a supplement against a serum, our guide to the peptide ingredients that have human data is the topical counterpart.

What is hydrolyzed collagen?

Collagen is the main structural protein in the dermis, the deeper layer of skin that gives it firmness. Intact collagen is a very large molecule. Hydrolyzed collagen, also sold as collagen peptides or collagen hydrolysate, has been broken down by enzymes into much smaller protein fragments that dissolve in water.

Commercial hydrolysates come from animal tissues. The trials in this guide used products from porcine skin, chicken feet and cartilage (Iwai et al., 2005), freshwater fish (Evans et al., 2021; Lee et al., 2024) and tuna (Morakul et al., 2024). Several abstracts don't report the source.

Products also differ in their peptide content. One trial used a "low-molecular-weight" collagen peptide standardized to more than 15% Gly-X-Y tripeptides, including 3% Gly-Pro-Hyp (Kim et al., 2018). Another compared two hydrolysates that differed mainly in how much Pro-Hyp and Hyp-Gly they contained (Inoue et al., 2016). These fragments come up again below, because they're the basis of the main theory for how oral collagen could reach skin.

Do collagen supplements for skin work in randomized trials?

Many individual trials report modest gains in hydration and elasticity, but most were industry-funded. Independent, high-quality trials show no clear effect.

The 7 controlled collagen trials below are the ones in our verified source set. Several were double-blind and placebo-controlled. All measured skin outcomes such as hydration, elasticity or wrinkle scores. We report only what the abstracts state.

Proksch et al., 2014: two doses, 8 weeks

In a double-blind, placebo-controlled RCT, 69 women aged 35–55 took 2.5 g or 5.0 g of collagen hydrolysate, or placebo, daily for 8 weeks (23 per group) (Proksch et al., 2014). Skin elasticity improved compared with placebo at both doses. Skin moisture and transepidermal water loss (TEWL, the rate water evaporates through skin) moved in a favorable direction only in a subgroup, and that change wasn't statistically significant.

The first author is from the University of Kiel. Funding is not reported in the abstract. Evidence: Limited.

Asserin et al., 2015: imaging of dermal collagen

This paper combined 2 placebo-controlled clinical trials with lab work on ex vivo skin explants (skin tissue kept alive outside the body) (Asserin et al., 2015). Hydration rose after 8 weeks. Ultrasound and confocal imaging showed higher dermal collagen density and less collagen fragmentation after 4 weeks, and the effect held at 12 weeks.

Sample sizes and dose are not reported in the abstract. The authors were affiliated with COSderma, BIO-EC, Unitec Foods and Rousselot, a collagen manufacturer. Evidence: Limited.

Kim et al., 2018: 1,000 mg of a tripeptide-rich product

In a double-blind RCT, 64 participants took 1,000 mg of low-molecular-weight collagen peptide or placebo daily for 12 weeks (Kim et al., 2018). Hydration was higher than placebo at 6 and 12 weeks. At 12 weeks, the visual wrinkle score and 3 wrinkle parameters had improved, and 2 of 3 elasticity measures were better than placebo.

The authors came from Newtree, the manufacturer, and Jellice. Evidence: Limited.

Inoue et al., 2016: does peptide content matter?

This double-blind, placebo-controlled RCT compared 2 collagen hydrolysates, one high and one low in Pro-Hyp and Hyp-Gly, over 8 weeks (Inoue et al., 2016). The high-content version improved facial moisture, elasticity, wrinkles and roughness more than both the low-content version and placebo.

Sample size and dose are not reported in the abstract. The first author is from Nitta Gelatin Inc. Evidence: Limited.

Evans et al., 2021: freshwater fish collagen, women 45–60

In a randomized, triple-blind, placebo-controlled trial, women aged 45–60 took hydrolyzed freshwater fish collagen (Vinh Wellness Collagen) for 12 weeks (Evans et al., 2021). Wrinkle scores fell 35% from baseline (P = .035), and the reduction on the right side of the face was 24% greater than with placebo. Elasticity improved only in the 45–54 subgroup.

Watch the comparison here. The 35% figure is change from the participants' own starting point, which is a weaker comparison than change against placebo. KGK Science, a contract research organization, ran the trial, and copyright is held by Vinh Hoan Corp, the manufacturer. Sample size and dose are not reported in the abstract. Evidence: Limited.

Lee et al., 2024: liquid fish collagen, industry-designed

In a double-blind RCT, 85 adults were randomized (78 completed) to 1,000 mg of liquid fish collagen (Tripep20, from freshwater Pangasius fish skin) or placebo daily for 12 weeks (Lee et al., 2024). Crow's-feet scores and skin roughness improved compared with placebo at 12 weeks. Elasticity was better than placebo at 6 weeks.

Amicogen Inc. fully funded the study, most authors were employees, and the funder was involved in the study design. Evidence: Limited.

Morakul et al., 2024: tuna collagen, university-led

In a double-blind, placebo-controlled RCT, 72 women (36 per group) took tuna collagen peptides for 8 weeks, then had 2 weeks of follow-up (Morakul et al., 2024). At 8 weeks the collagen group did significantly better than placebo on hydration, elasticity, skin density and every other measured parameter except facial TEWL.

The authors are from Mahidol University. Dose and funding are not reported in the abstract. Of the 7 trials, this is the one where the abstract shows a university team without a listed manufacturer affiliation. Evidence: Limited.

Who funded the collagen supplement trials?

The table below summarizes what each collagen trial's abstract says about who ran and funded it. "Not reported" means the abstract doesn't say. It doesn't mean there was no industry involvement.

Industry funding doesn't automatically make a trial wrong. Manufacturers pay for most supplement research because few other funders will. But it does affect which products get tested, which outcomes get reported and which studies get published. That's why the funding-split analysis in the next section matters.

Why don't the collagen meta-analyses agree?

A meta-analysis pools results from many trials to estimate an average effect. All 3 in our sources found benefits overall. They differ in how hard they looked at study quality and funding.

de Miranda et al., 2021: favorable overall

This meta-analysis (about 126 citations on Semantic Scholar) pooled 19 RCTs with 1,125 participants aged 20–70, 95% of them women (de Miranda et al., 2021). Results favored hydrolyzed collagen for hydration, elasticity and wrinkles, and the authors concluded that 90 days of use was effective.

Note who was studied. With 95% women, the results say little about men.

Pu et al., 2023: favorable, with bias flagged

This meta-analysis (about 105 citations) pooled 26 RCTs with 1,721 patients (Pu et al., 2023). Hydrolyzed collagen improved hydration and elasticity compared with placebo. The hydration effect varied by collagen source and by how long people took it.

The authors, from Taipei Medical University and Cochrane Taiwan, declared no conflicts of interest. They also flagged several biases in the underlying trials and called for larger RCTs. So an independent team found a pooled benefit, but warned that it rests on imperfect trials.

Myung & Park, 2025: the benefit disappears in the better trials

This meta-analysis pooled 23 RCTs with 1,474 participants (Myung & Park, 2025). Its methods are solid, but it is early: published in 2025, it has about 20 citations so far and hasn't yet been replicated or debated much in the literature. Across all 23, collagen significantly improved hydration, elasticity and wrinkles, which matches the earlier reviews.

Then the authors split the trials into subgroups:

• Funding: trials not funded by pharmaceutical companies showed no effect on hydration, elasticity or wrinkles. Industry-funded trials showed significant effects.
• Quality: high-quality trials showed no significant effect in any category. Low-quality trials showed an improvement in elasticity.

The authors concluded there is "no clinical evidence to support the use of collagen supplements to prevent or treat skin aging." Evidence: Mixed / contested.

How to read the split

The pooled averages are positive, and the subgroups most protected from bias are null. Usually that pattern means the pooled effect is at least partly inflated by weaker or sponsor-run studies. It doesn't prove collagen does nothing. Subgroup analyses have less statistical power, and "no significant effect" isn't the same as "proven zero effect."

Here is our honest read. The case for collagen supplements for skin is weaker than the headline numbers suggest, and the independent, high-quality evidence doesn't yet show a benefit. Morakul 2024, a university-led trial, did report positive results (Morakul et al., 2024). One trial doesn't settle the disagreement, though, and we don't know from the abstract how it was funded.

Does swallowed collagen reach your skin?

The usual objection is that collagen is just protein, so digestion breaks it into amino acids like any other food. That's only partly right.

What shows up in blood: Iwai 2005

Healthy volunteers who had fasted for 12 hours drank 9.4–23 g of gelatin hydrolysates made from porcine skin, chicken feet or cartilage (Iwai et al., 2005). Hydroxyproline (an amino acid found almost only in collagen) appeared in blood still bound in small peptides. It peaked at 20–60 nmol/mL of plasma at 1–2 hours and fell by half by 4 hours. The main peptide was Pro-Hyp, along with Ala-Hyp, Ala-Hyp-Gly, Pro-Hyp-Gly, Leu-Hyp, Ile-Hyp and Phe-Hyp.

So some collagen does get past digestion as short peptides, not just single amino acids. The number of volunteers is not reported in the abstract. This is the foundational paper on collagen peptide absorption, with about 399 citations. Evidence: Early / preliminary (for absorption; this study measured blood levels, not skin outcomes).

What those peptides do in a dish: Shigemura 2009

In mouse skin discs and cultured fibroblasts (the cells that make collagen), Pro-Hyp at 200 nmol/mL increased the number of fibroblasts migrating out of the skin (Shigemura et al., 2009). Across 0–1,000 nmol/mL, it boosted fibroblast growth on collagen gel, and higher doses had larger effects. Evidence: Lab / animal only.

The concentration gap

Put the 2 numbers next to each other. The migration effect used 200 nmol/mL of Pro-Hyp. In Iwai's volunteers, all peptide-bound hydroxyproline combined peaked at 20–60 nmol/mL, and it came from doses of 9.4–23 g. That's more than most skin trials used. Pro-Hyp is only part of that total.

So the lab effect showed up at a concentration several times higher than the peak blood level, and blood levels dropped by half within 4 hours. Neither study measured how much Pro-Hyp reaches the dermis in people. The mechanism is plausible, but it isn't proven in human skin.

How much of a collagen supplement for skin did the trials use?

Trial doses vary, and several abstracts don't report them at all:

• 2.5 g or 5.0 g daily for 8 weeks (Proksch et al., 2014)
• 1,000 mg daily of a tripeptide-standardized product for 12 weeks (Kim et al., 2018)
• 1,000 mg daily of liquid fish collagen for 12 weeks (Lee et al., 2024)
• The Asserin, Inoue, Evans and Morakul abstracts don't state the dose.

Proksch is the only trial here that compared 2 doses, and both beat placebo for elasticity. The abstract information we have doesn't show 5 g doing better than 2.5 g. No trial in our sources established a dose-response curve, a minimum effective dose or an upper limit where benefits level off. Evidence: Limited.

What this means for you: the trials don't tell you that a bigger scoop works better. Doses in the 1,000 mg–5 g range are the ones that were tested. Results with standardized products such as Kim's tripeptide-rich peptide may not carry over to a generic powder at the same weight.

How long before you'd expect to see anything?

A recurring question in skincare communities comes from people who took collagen for about a month, saw nothing, and want to know whether to keep going. The trial timelines give a partial answer.

• The earliest reported changes were in imaging, not appearance: higher dermal collagen density at 4 weeks (Asserin et al., 2015).
• Hydration and elasticity differences first showed up at 6 weeks in 2 trials (Kim et al., 2018; Lee et al., 2024).
• Most primary endpoints were at 8 weeks (Proksch et al., 2014; Inoue et al., 2016; Morakul et al., 2024) or 12 weeks (Evans et al., 2021; Lee et al., 2024).
• One meta-analysis concluded that 90 days was the effective period (de Miranda et al., 2021).

So 1 month is shorter than nearly every trial's endpoint, and seeing nothing at that point doesn't tell you much. Keep in mind that these changes were measured with instruments such as corneometers, elastometers and skin imaging. A statistically significant change on a device may not be something you notice in the mirror. And the independent-trial subgroup in Myung 2025 found no effect at any duration (Myung & Park, 2025).

Is marine, bovine or porcine collagen better for skin?

Another frequent question is whether marine collagen beats bovine. The marketing usually says yes. Our sources don't support a clear answer.

• No head-to-head trial. None of the trials in our source set randomized people to marine versus bovine or porcine collagen.
• Pooled comparison by source: in the Pu 2023 meta-analysis, collagen source made no significant difference for elasticity (p = 0.21). Hydration effects did vary by source and duration (Pu et al., 2023). That's a comparison across different studies, which can differ in many ways besides the collagen source.
• Fish-derived products in the trials: Evans (freshwater fish), Lee (Pangasius fish skin) and Morakul (tuna) all tested fish collagen, and all 3 reported positive results (Evans et al., 2021; Lee et al., 2024; Morakul et al., 2024). Two of those 3 were manufacturer-linked, so this doesn't show marine collagen is better.

Evidence: Limited. If you choose between sources, base it on dietary preference, allergies, price and third-party testing. The trial data doesn't pick a winner. If you have a fish or shellfish allergy, ask your clinician before trying marine products.

Does the brand or a "clinically studied" peptide matter?

People often ask whether a branded collagen ingredient is worth paying more for. The honest answer has 2 parts.

Composition may matter. In Inoue 2016, a hydrolysate high in Pro-Hyp and Hyp-Gly beat a low-content version on several skin measures (Inoue et al., 2016). Kim 2018 tested a product standardized to Gly-X-Y tripeptides (Kim et al., 2018). So "collagen" isn't one interchangeable ingredient. A study of one product doesn't automatically apply to another.

But "studied" often means "studied by the maker." The Inoue first author is from a gelatin company, the Kim authors are from the manufacturer, and Lee was fully funded by Amicogen, which helped design it (Lee et al., 2024). None of these product-specific results has an independent replication in our sources.

A useful filter: when a label says "clinically studied," look for the trial. Check whether it tested that exact ingredient at the dose in your product, how many people were in it, how long it ran, whether outcomes were compared with placebo or only with baseline, and who paid for it. The 7 abstracts above are a reasonable template for those questions.

Are collagen supplements safe, and who should check with a clinician first?

The abstracts in our source set focus on skin outcomes. They don't give enough adverse-event detail for us to summarize side effect rates, so we won't claim any.

Practical points that don't depend on trial data: collagen is an animal-derived protein, so source matters if you have food allergies or dietary restrictions. If you're pregnant, nursing, managing kidney disease or have been told to limit protein, check with a clinician before adding a protein supplement.

Is oral collagen better than topical peptides?

Oral collagen and topical peptides often get treated as rivals. They're different interventions with different evidence problems.

Oral collagen has a relatively large trial record (3 meta-analyses with 19–26 RCTs each), but the independent, high-quality subset is null (Myung & Park, 2025).

Topical peptides have a different gap: fewer human trials. A 2025 review noted a surprising absence of clinical studies for topical GHK-Cu, the copper peptide (Mortazavi et al., 2025; a narrative review with about 12 citations so far. Evidence: limited.). GHK-Cu is also very water-loving (log D about −2.4), which makes it harder to get through the skin's oily outer layer (Badenhorst et al., 2016). Some topical peptides do have small human studies. In one study of 24 volunteers over 60 days, acetyl hexapeptide-3 (Argireline) lowered TEWL (Raikou et al., 2017). Evidence: Early / preliminary.

So neither route has clear superiority on current evidence. We dig into the topical side in our copper peptides for skin guide, which covers what GHK-Cu data exists and where it's mostly lab-based. Our peptide ingredients guide compares Matrixyl, Argireline and others by the human evidence behind each.

Hydration: a cheaper, better-tested lever

Many collagen trials list skin hydration as a main outcome. If hydration is your main goal, moisturizers have stronger evidence in at least one population. A Cochrane review of 77 RCTs with 6,603 people with eczema found that moisturizers lowered investigator-rated severity and reduced flares (RR 0.33) compared with no moisturizer (van Zuuren et al., 2017). The authors found no reliable evidence that any one moisturizer beats another. Evidence: Well-established (in eczema; healthy skin wasn't the population studied).

Our skin hydration and barrier guide explains humectants, occlusives and barrier lipids. If you want to see where an optional supplement could fit alongside sunscreen, moisturizer and actives, our step-by-step skincare protocol puts the pieces in order.

Do collagen supplements help skin on GLP-1 medications?

Readers on semaglutide or tirzepatide often ask whether collagen can offset facial changes during weight loss. Here's what our sources support, and what they don't.

A 2026 systematic review of 40 human studies, including case reports and observational studies, described facial volume loss, dermal thinning and reduced elasticity in GLP-1 users. Risk factors included advanced age, rapid weight loss, poor hydration and insufficient protein intake. The authors recommended nutritional optimization and called for prospective studies (Barone et al., 2026). The review is brand new and has no citations yet. A 2024 narrative review suggested that fat loss and changes in adipose-derived stem cells may affect skin structure and barrier function. That's a hypothesis, not trial data (Ridha et al., 2024).

No study in our sources tests collagen supplements in GLP-1 users. Whether collagen helps in that setting is unknown. Protein intake and medication decisions belong with your prescribing clinician. Never start, stop or change a GLP-1 medication based on skincare concerns.

Where the evidence stops

• Independent replication. The funding-split result in Myung 2025 needs testing in large, independently funded, preregistered trials (Myung & Park, 2025).
• Dose-response. No trial in our sources maps how effect size changes with dose, or establishes a minimum dose.
• Source comparisons. No head-to-head marine vs bovine vs porcine trial in our sources. The source comparison in Pu 2023 is indirect (Pu et al., 2023).
• Skin-level exposure. We know what peptide levels look like in blood (Iwai et al., 2005). We don't know what reaches human dermis, or whether it matches the concentrations that worked in mouse tissue (Shigemura et al., 2009).
• Who was studied. Participants were mostly women, mostly middle-aged (de Miranda et al., 2021). Data on men, younger adults and people with darker skin types is thin in these abstracts.
• Durability. Most trials stopped at 8–12 weeks. We don't know what happens after a year, or after you stop.
• Perceptible change. Instrument-measured gains aren't the same as visible change, and few abstracts report whether participants noticed a difference.
• GLP-1 users. Collagen supplements haven't been tested in this group in our sources.

FAQ

Do collagen supplements for skin actually work? Pooled across all trials, they show modest improvements in hydration and elasticity (Pu et al., 2023). But when one 2025 meta-analysis looked only at non-industry-funded or high-quality trials, the effect disappeared (Myung & Park, 2025). The fair summary is "contested," not "proven" or "useless."

Is marine collagen better than bovine collagen for skin? No trial in our sources compared them directly. In a meta-analysis of 26 RCTs, source made no significant difference for elasticity (p = 0.21), though hydration effects varied by source (Pu et al., 2023). Choose based on diet, allergies and quality testing, not marketing.

I took collagen for a month and saw nothing. How long should I wait? Most trials measured results at 8–12 weeks. The earliest instrument-detected changes in hydration or elasticity appeared at 6 weeks (Kim et al., 2018; Lee et al., 2024). One month is too short to judge. Even at 12 weeks, though, changes measured on a device may not be visible in the mirror.

Does a branded or "clinically studied" peptide matter? Composition may matter. A hydrolysate high in Pro-Hyp beat a low-content version in one trial (Inoue et al., 2016). But most product-specific trials were run or funded by the maker, such as Lee 2024, which Amicogen fully funded (Lee et al., 2024). Check the exact trial, its n, dose, comparator and funder.

How much collagen did the skin trials use? Doses ranged from 1,000 mg daily (Kim et al., 2018; Lee et al., 2024) to 2.5–5 g daily (Proksch et al., 2014). Several abstracts don't report a dose. No trial in our sources showed that a higher dose works better.

Should I use oral collagen or topical peptides? Each has a different evidence gap. Oral collagen has many trials but a null independent subset. Topical peptides like GHK-Cu have few clinical studies (Mortazavi et al., 2025). See our copper peptides guide and peptide ingredients guide to compare.

Can collagen supplements help skin changes on GLP-1 medications? We don't know. No study in our sources tests that. A 2026 systematic review lists insufficient protein intake and rapid weight loss among risk factors for skin changes in GLP-1 users (Barone et al., 2026). Discuss nutrition and medication questions with your prescribing clinician.

Go deeper

• Copper peptides for skin: what GHK-Cu research shows
• The peptide ingredients with human data, compared
• Skin hydration and barrier repair: humectants, occlusives and lipids
• A step-by-step skincare protocol

References

Full titles and author lists are on each PubMed page.

1. Myung SK, Park Y. Am J Med. 2025. Meta-analysis of 23 RCTs, 1,474 participants; subgroups by funding and study quality. https://pubmed.ncbi.nlm.nih.gov/40324552/
2. Pu SY, et al. Nutrients. 2023. Meta-analysis of 26 RCTs, 1,721 patients; authors declare no conflicts of interest. https://pubmed.ncbi.nlm.nih.gov/37432180/
3. de Miranda RB, et al. Int J Dermatol. 2021. Meta-analysis of 19 RCTs, 1,125 participants aged 20–70 (95% women). https://pubmed.ncbi.nlm.nih.gov/33742704/
4. Proksch E, et al. Skin Pharmacol Physiol. 2014. Double-blind placebo-controlled RCT, n = 69 women, 8 weeks, 2.5 g or 5.0 g daily. https://pubmed.ncbi.nlm.nih.gov/23949208/
5. Asserin J, et al. J Cosmet Dermatol. 2015. Two placebo-controlled trials plus ex vivo explants; n not reported in the abstract; authors include Rousselot affiliation. https://pubmed.ncbi.nlm.nih.gov/26362110/
6. Kim DU, et al. Nutrients. 2018. Double-blind RCT, n = 64, 12 weeks, 1,000 mg daily; authors from Newtree and Jellice. https://pubmed.ncbi.nlm.nih.gov/29949889/
7. Inoue N, et al. J Sci Food Agric. 2016. Double-blind placebo-controlled RCT, 8 weeks, high vs low Pro-Hyp hydrolysates; n not reported in the abstract; first author Nitta Gelatin Inc. https://pubmed.ncbi.nlm.nih.gov/26840887/
8. Evans M, et al. J Cosmet Dermatol. 2021. Triple-blind placebo-controlled RCT, women 45–60, 12 weeks; n not reported in the abstract; run by KGK Science, copyright Vinh Hoan Corp. https://pubmed.ncbi.nlm.nih.gov/32799362/
9. Lee JS, et al. Nutr Res Pract. 2024. Double-blind RCT, n = 85 randomized (78 completers), 12 weeks, 1,000 mg daily; funded by Amicogen Inc. https://pubmed.ncbi.nlm.nih.gov/38854476/
10. Morakul B, et al. J Cosmet Dermatol. 2024. Double-blind placebo-controlled RCT, n = 72 women, 8 weeks plus 2-week follow-up; Mahidol University. https://pubmed.ncbi.nlm.nih.gov/39075819/
11. Iwai K, et al. J Agric Food Chem. 2005. Human ingestion study, 9.4–23 g gelatin hydrolysates; n not reported in the abstract. https://pubmed.ncbi.nlm.nih.gov/16076145/
12. Shigemura Y, et al. J Agric Food Chem. 2009. In vitro / animal study, mouse skin and fibroblasts. https://pubmed.ncbi.nlm.nih.gov/19128041/
13. Mortazavi, et al. 2025. Review of GHK-Cu, noting a lack of clinical studies for topical use. https://pubmed.ncbi.nlm.nih.gov/39963574/
14. Badenhorst, et al. 2016. Physicochemical study of GHK-Cu (log D about −2.4). https://pubmed.ncbi.nlm.nih.gov/25384620/
15. Raikou, et al. 2017. Human study, n = 24, 60 days, acetyl hexapeptide-3 and TEWL. https://pubmed.ncbi.nlm.nih.gov/28150423/
16. van Zuuren EJ, et al. Cochrane Database Syst Rev. 2017. Systematic review of 77 RCTs, 6,603 participants with eczema. https://pubmed.ncbi.nlm.nih.gov/28166390/
17. Barone M, et al. Aesthetic Plast Surg. 2026. Systematic review of 40 human studies on GLP-1-associated facial and skin changes. https://pubmed.ncbi.nlm.nih.gov/42162206/
18. Ridha Z, et al. Aesthet Surg J. 2024. Narrative review of GLP-1 receptor agonists and facial aging. https://pubmed.ncbi.nlm.nih.gov/38874170/

Disclosure: This article is for general information only and is not medical advice. It summarizes published research and does not replace advice from a dermatologist, physician or registered dietitian. Talk to a qualified clinician before starting a supplement, especially if you are pregnant, nursing, have food allergies, have kidney disease or take prescription medication. Never start, stop or change a GLP-1 medication without your prescriber. This article contains no affiliate links, and no manufacturer reviewed or paid for it.

For educational purposes only; not medical advice. See our disclaimer and research method.