Verdict: GHK-Cu is a copper peptide with small topical human trials. GLOW (GHK-Cu, BPC-157, TB-500) and KLOW (GLOW plus KPV) are unapproved blends that no human trial has ever tested. None of the three is an FDA-approved drug, and both blends contain peptides banned in sport.
GLOW and KLOW are product names used by sellers, not drugs defined by any regulator or journal. The evidence behind them comes from each ingredient tested alone, mostly in cells and animals. As of 2026-09-30, the FDA’s compounding page lists GHK-Cu, BPC-157, TB-500 and KPV only as “withdrawn by nominators” from Category 2 (FDA). None of the four has been placed in Category 1.
| Item | GHK-Cu | GLOW | KLOW |
|---|---|---|---|
| US FDA status | Not an approved drug | Not approved | Not approved |
| Compounding (503A/503B) | Injectable GHK-Cu withdrawn from Category 2; not on the 503A bulks list. PCAC voted on 2026-07-23 to recommend BPC-157 and TB-500 for 503A listing (8–6 each); advisory only, no FDA rule yet (FDA PCAC meeting) | All three parts withdrawn from Category 2; none on the bulks list. PCAC voted on 2026-07-23 to recommend BPC-157, TB-500 and KPV for 503A listing (8–6 each); advisory only, no FDA rule yet (FDA PCAC meeting) | All four parts withdrawn from Category 2; none on the bulks list |
| WADA 2026 | Not named; USADA lists cosmetic GHK as not prohibited | Prohibited: BPC-157 (S0), TB-500 (S2) | Prohibited: BPC-157 (S0), TB-500 (S2) |
| Strongest evidence | Human RCT (topical, small) | No study of the blend | No study of the blend |
| Human trials | 2 published topical RCTs; 1 registered, not yet recruiting: NCT07706361 | 0 of the blend | 0 of the blend |
| Last checked | 2026-10-18 | 2026-09-30 | 2026-09-30 |
Sources for the table: FDA Category 2 page (updated 2026-04-22), WADA Prohibited List, USADA, and the trials cited below.
Key points:
- The only thing that separates GLOW from KLOW is KPV. The FDA says it has found no human exposure data for KPV by any route (FDA).
- The FDA flags a possible immunogenicity risk (an unwanted immune reaction) for GHK-Cu, BPC-157 and TB-500 given by certain routes, linked to peptide clumping and impurities (FDA).
- In a 2026 rat tendon study, BPC-157 and TB-500 together did no better than either one alone [Animal] (Biçer 2026).
- In a small randomized trial after laser resurfacing, topical GHK-Cu did not improve redness, wrinkles or skin quality on objective measures [Human RCT, n=13] (Miller 2006).
- For athletes, both blends contain two substances that WADA prohibits at all times (WADA).
KLOW vs GLOW vs GHK-Cu at a glance
| Feature | GHK-Cu | GLOW | KLOW |
|---|---|---|---|
| What it is | One copper-binding tripeptide | Blend: GHK-Cu, BPC-157, TB-500 | Blend: GLOW plus KPV |
| Class | Copper peptide | Multi-peptide mix | Multi-peptide mix |
| Main research focus | Skin repair, wound healing | Parts studied for skin, tendon, gut | Same, plus gut inflammation (KPV) |
| Human evidence | Small topical RCTs | None for the blend | None for the blend |
| Best evidence for any part | Human RCT (topical) | BPC-157: case series; TB-500: none | Same as GLOW; KPV: animal only |
| Routes studied in people | Topical gel, skin products | No blend route studied | No blend route studied |
| FDA approval | No | No | No |
| WADA | Not named | Contains S0 and S2 substances | Contains S0 and S2 substances |
| Timelines reported | 12 weeks (laser trial) | None for the blend | None for the blend |
| Main safety concerns | Immunogenicity if injected; limited human data | Immunogenicity, impurities, unknown interactions | As GLOW, plus no human KPV data |
What is GHK-Cu?
GHK-Cu is the tripeptide glycyl-L-histidyl-L-lysine bound to copper. GHK occurs naturally in the human body. In lab and animal work it stimulated the growth of blood vessels and nerves, raised collagen, elastin and glycosaminoglycan production, and supported dermal fibroblasts, the cells that build skin’s support structure [Lab/Animal] (Pickart 2018). It is widely used in cosmetics, and USADA lists non-palmitoylated tripeptide-1 (GHK) among cosmetic peptides that are not prohibited (USADA). Injectable GHK-Cu is a separate matter: the FDA says there are “limited data in humans to inform safety-related considerations” (FDA).
What is GLOW?
GLOW is a seller’s name for a mix of GHK-Cu, BPC-157 and TB-500. BPC-157 is a synthetic 15-amino-acid peptide. A 2025 review of it found strong regenerative results in animals but only three small human pilot studies (McGuire 2025). TB-500 is a short synthetic copy of one active region of thymosin beta-4, a natural repair protein (Ho 2012). No published study has tested the three-part blend. Our BPC-157 vs TB-500 comparison covers those two peptides in more depth.
What is KLOW?
KLOW is GLOW with KPV added. KPV is the tripeptide lysine-proline-valine, which is linked to the anti-inflammatory hormone α-MSH (alpha-melanocyte-stimulating hormone) (Gravina 2023). In cells, KPV entered through the PepT1 transporter and dampened inflammatory signaling at nanomolar concentrations. In mice, oral KPV reduced chemically induced colitis [Lab; Animal] (Dalmasso 2008). The FDA states that it “has not identified any human exposure data on drug products containing KPV administered via any route of administration” (FDA).
How do they work differently?
These mechanisms come from lab and animal studies. No study has measured how the ingredients act together inside the human body.
- GHK-Cu: a copper-carrying peptide that raised collagen and elastin production and supported fibroblast function in lab studies [Lab] (Pickart 2018).
- BPC-157 (in GLOW and KLOW): reported to protect cells and aid repair in animal models of musculoskeletal injury [Animal] (McGuire 2025).
- TB-500 (in GLOW and KLOW): comes from thymosin beta-4, which sped up skin healing in normal, diabetic, aged and steroid-treated animals [Animal] (Treadwell 2012).
- KPV (KLOW only): taken up by gut cells through PepT1, where it lowered inflammatory signaling [Lab; Animal] (Dalmasso 2008).
Evidence head-to-head
This table scores the best evidence for each outcome. For the blends, the cells show the best evidence for any single ingredient, because the blends themselves have none.
| Outcome | GHK-Cu | GLOW | KLOW |
|---|---|---|---|
| Chronic wound / ulcer healing | Human RCT: diabetic ulcers closed faster than vehicle (Mulder 1994) | Human RCT of full thymosin beta-4 gel, not TB-500 (Guarnera 2010) | Same as GLOW |
| Recovery after laser resurfacing | Human RCT, n=13: no objective benefit (Miller 2006) | No data | No data |
| Tendon repair | No data | Animal (rat): parts helped alone, no added benefit together (Biçer 2026) | Same as GLOW |
| Knee pain | No data | BPC-157: Human case series, n=16, uncontrolled (Lee 2021) | Same as GLOW |
| Gut inflammation | No data | No human data | KPV: Animal (mouse colitis) (Dalmasso 2008) |
| Human safety data | Topical trials only | BPC-157: IV pilot, n=2 (Lee 2025) | As GLOW; KPV: none (FDA) |
Some details matter here. The diabetic-ulcer trial was multicenter, randomized, evaluator-blinded and placebo-controlled. Median ulcer closure was 98.5% with GHK-Cu gel versus 60.8% with vehicle, and among plantar ulcers treated immediately after debridement, infections occurred in 7% versus 34% [Human RCT] (Mulder 1994). The thymosin beta-4 ulcer trial used the full protein as a gel, not the TB-500 fragment. In its posted results, 12 of 55 treated patients and 4 of 17 placebo patients had closed wounds by day 84 [Human RCT, n=72] (NCT00832091). That is roughly the same rate in both groups. A 2026 scoping review of peptides in sports medicine concluded that current human trials do not back up their claimed benefits (Tewari 2026).
Registered trials to watch
- GHK-Cu, registered and not yet recruiting (NCT07706361).
- BPC-157 after rotator cuff repair surgery, phase 1, not yet recruiting (NCT07803250).
- Oral BPC-157 safety study, phase 1, status unknown since 2015 (NCT02637284).
- A third registered BPC-157 trial (NCT07752381); none of the three has posted results.
- TB-500: no registered trial tests the fragment; the 19 registered thymosin beta-4 trials all use the full-length protein. NCT07487363, earlier listed here as a TB-500 trial, describes itself as a fictional example study.
No registered trial on ClinicalTrials.gov tests GLOW, KLOW or any mix of these four peptides (search run 2026-09-30).
Which fits which goal?
These are statements about evidence, not recommendations.
- GHK-Cu has more evidence for topical skin and wound outcomes. It is the only one of the three with randomized human trials, and those trials tested creams and gels, not injections (Mulder 1994; Miller 2006).
- GLOW’s ingredients have more evidence for tendon and soft-tissue repair, but only in animals and in one uncontrolled human case series (Biçer 2026; Lee 2021).
- KLOW adds KPV, which has evidence for reduced gut inflammation in mice and none in people (Dalmasso 2008).
Adding ingredients does not add evidence. Each extra peptide brings its own unknowns, and no study shows that the blends work better than GHK-Cu alone. A clinician is the person to decide whether any of these fits a specific health situation.
Can they be combined?
GLOW and KLOW are themselves combinations. Only two studies touch on combining any of their ingredients. In the knee-pain chart review, 4 patients received BPC-157 with thymosin beta-4, and 3 of them reported improvement. The study had no control group [Human case series] (Lee 2021). In rats with repaired Achilles tendons, the BPC-157 plus TB-500 pairing gave no additional benefit over either peptide alone [Animal] (Biçer 2026). No controlled human study has tested GLOW, KLOW, or GHK-Cu combined with any of the other three peptides.
Safety and regulatory status
United States (FDA)
None of the four peptides is an approved drug. On its compounding safety page, updated 2026-04-22, the FDA lists GHK-Cu (for injectable routes), BPC-157, KPV and TB-500 as “previously in Category 2 – withdrawn by nominators.” It still describes its concerns for each: possible immunogenicity from aggregation and peptide-related impurities for GHK-Cu and TB-500, impurity and characterization problems plus insufficient human safety data for BPC-157, and no human exposure data at all for KPV (FDA). Being withdrawn from Category 2 is not the same as approval. BPC-157, KPV and TB-500 were reviewed by the FDA’s Pharmacy Compounding Advisory Committee on 2026-07-23. GHK-Cu was not on the agenda (FDA PCAC). The committee’s advice is non-binding, and none of the four had been added to the 503A bulks list as of 2026-09-30.
Product quality
Reviews published in 2026 warn that unregulated peptides carry risks of contamination, manufacturing impurities and inaccurate dosing, and that they lack established human safety profiles (Moiz 2026). Gray-market products are of uncertain identity, purity, potency and sterility (Hailu 2026). In a blend, a problem with any one ingredient becomes a problem with the whole product.
Sport (WADA and USADA)
WADA’s 2026 list names BPC-157 under S0 (non-approved substances) and “thymosin-β4 and its derivatives, e.g. TB-500” under S2.3 (growth factors). Both are prohibited at all times (WADA; USADA). That makes both GLOW and KLOW prohibited for tested athletes. KPV is not named, but S0 covers any pharmacological substance without approval for human therapeutic use (WADA). USADA notes that topical use of a prohibited peptide is “just as prohibited” as injected or oral use, and it tells athletes to check products on Global DRO (USADA).
How long do effects take in studies?
- GHK-Cu, laser-resurfaced skin: assessed over 12 weeks, with no objective difference from the comparison regimen [Human RCT, n=13] (Miller 2006).
- Thymosin beta-4 gel, venous ulcers: the authors reported complete healing within 3 months in about 25% of patients (Guarnera 2010). The posted day-84 results showed similar closure rates with placebo (NCT00832091).
- BPC-157 and TB-500, rat tendon: the biomechanical difference for TB-500 appeared at four weeks [Animal] (Biçer 2026).
No study reports a timeline for GLOW or KLOW.
What users report
Reports about KLOW, GLOW, and standalone GHK-Cu circulating on Reddit, X, YouTube, and bodybuilding or biohacking forums are unverified self-reports from people who mostly obtained these products from unregulated sellers, and none of it counts as clinical evidence. People who post about GLOW commonly report brighter, smoother-looking skin and softer fine lines within about four weeks, with fuller effects on skin texture and recovery described over eight to twelve weeks; those who discuss KLOW tend to focus more on hair, describing reduced shedding and slow regrowth over a similar or longer timeframe. Posts about plain GHK-Cu skew toward topical skin use, with people describing gradual firmness and glow rather than dramatic change.
A recurring complaint across all three is that results feel underwhelming compared to marketing claims, and some users say they noticed nothing at all. Others describe injection-site soreness, redness, or bruising, and a subset report headaches, fatigue, or skin irritation they attribute to the product. Cost is a frequent gripe, especially for KLOW and GLOW blends, which people say are pricier than single-peptide options for uncertain payoff.
Much of the online arguing centers on product quality: people trade warnings about underdosed or fake vials, inconsistent batches between sellers, and whether visible effects are real or placebo. Some also debate whether GLOW’s or KLOW’s added ingredients meaningfully outperform GHK-Cu alone, with no consensus reached in these discussions.
Frequently asked questions
What is the difference between GLOW and KLOW?
KLOW contains everything in GLOW (GHK-Cu, BPC-157 and TB-500) plus KPV, an anti-inflammatory tripeptide. KPV’s evidence comes from cells and mice: in mice, oral KPV reduced chemically induced colitis. The FDA says it has found no human exposure data for KPV by any route, so KLOW’s extra ingredient is its least-studied one (FDA).
Is KLOW or GLOW FDA approved?
No. Neither blend, nor any of its ingredients, is an FDA-approved drug. The FDA lists GHK-Cu, BPC-157, TB-500 and KPV as withdrawn by nominators from its Category 2 compounding list. It has not moved them to Category 1 or added them to the 503A bulks list, and it still cites immunogenicity and impurity concerns (FDA).
Is GHK-Cu alone better studied than GLOW or KLOW?
Yes. GHK-Cu has small randomized human trials, all of topical products. In one, a GHK-Cu gel sped closure of diabetic foot ulcers compared with a vehicle gel. No trial has tested GLOW or KLOW, and no study shows that either blend outperforms GHK-Cu alone (Mulder 1994).
Are GLOW and KLOW banned in sports?
Yes, for athletes under WADA rules. Both blends contain BPC-157, which is prohibited under S0, and TB-500, which WADA lists under S2.3 as a thymosin-β4 derivative. Both are prohibited in and out of competition. USADA states that topical use of a prohibited peptide carries the same status as injected use (USADA).
Is topical GHK-Cu different from injected GHK-Cu?
Yes. The human trials of GHK-Cu used gels and skincare products, and USADA lists cosmetic GHK among non-prohibited peptides. Injected GHK-Cu has no published controlled human trials. The FDA’s concerns about immunogenicity, aggregation and impurities apply specifically to injectable routes, where it says human data are limited (FDA).
References
- US Food and Drug Administration. Certain bulk drug substances for use in compounding that may present significant safety risks (updated 2026-04-22). fda.gov
- US Food and Drug Administration. July 23–24, 2026 meeting of the Pharmacy Compounding Advisory Committee. fda.gov
- World Anti-Doping Agency. The Prohibited List (2026). wada-ama.org
- USADA. BPC-157: peptide prohibited. usada.org
- USADA. Peptides and growth factors in cosmetics: are they banned? usada.org
- Mulder GD, Patt LM, Sanders L, et al. 1994. Enhanced healing of ulcers in patients with diabetes by topical treatment with glycyl-L-histidyl-L-lysine copper. Wound Repair Regen. PubMed 17147644
- Miller TR, Wagner JD, Baack BR, Eisbach KJ. 2006. Effects of topical copper tripeptide complex on CO2 laser-resurfaced skin. Arch Facial Plast Surg. PubMed 16847171
- Pickart L, Margolina A. 2018. Regenerative and protective actions of the GHK-Cu peptide in the light of the new gene data. Int J Mol Sci. PubMed 29986520
- Dalmasso G, Charrier-Hisamuddin L, Nguyen HT, et al. 2008. PepT1-mediated tripeptide KPV uptake reduces intestinal inflammation. Gastroenterology. PubMed 18061177
- Gravina AG, et al. 2023. Melanocortin system in inflammatory bowel diseases. Cells. PubMed 37508552
- McGuire FP, Martinez R, Lenz A, Skinner L, Cushman DM. 2025. Regeneration or risk? A narrative review of BPC-157 for musculoskeletal healing. Curr Rev Musculoskelet Med. PubMed 40789979
- Lee E, Padgett B. 2021. Intra-articular injection of BPC 157 for multiple types of knee pain. Altern Ther Health Med. PubMed 34324435
- Lee E, Burgess K. 2025. Safety of intravenous infusion of BPC157 in humans: a pilot study. Altern Ther Health Med. PubMed 40131143
- Treadwell T, Kleinman HK, Crockford D, et al. 2012. The regenerative peptide thymosin β4 accelerates the rate of dermal healing in preclinical animal models and in patients. Ann N Y Acad Sci. PubMed 23050815
- Guarnera G, DeRosa A, Camerini R, et al. 2010. The effect of thymosin treatment of venous ulcers. Ann N Y Acad Sci. PubMed 20536470
- RegeneRx Biopharmaceuticals. Study of thymosin beta 4 in patients with venous stasis ulcers (results posted 2010). ClinicalTrials.gov. NCT00832091
- Biçer O, Adanir O, Güleryüz Y, et al. 2026. Effects of BPC-157 and TB-500 on Achilles tendon healing in rats: a histopathological and biomechanical study. Jt Dis Relat Surg. PubMed 42542926
- Tewari K, Liu TP, Im C, et al. 2026. Peptide supplements and therapeutic applications in sports medicine: a scoping review. Am J Sports Med. PubMed 42578445
- Moiz A, O’Keefe EL, O’Keefe JH. 2026. Dangers of injectable peptides and other unregulated “biohacking” drugs. Mo Med. PubMed 42757290
- Hailu KT, Abriha FN, Duguma YM, et al. 2026. Unregulated peptide use in the age of biohacking. Cureus. PubMed 42437212
- Ho EN, et al. 2012. Doping control analysis of TB-500, a synthetic version of an active region of thymosin β4, in equine urine and plasma. J Chromatogr A. PubMed 23084823
- University of Arkansas. Impact of BPC-157 on recovery from rotator cuff repair surgery. ClinicalTrials.gov. NCT07803250
- PharmaCotherapia d.o.o. PCO-02: safety and pharmacokinetics trial. ClinicalTrials.gov. NCT02637284
Change log
2026-10-26: links to related entries added; no change to the facts.
2026-10-18: removed ClinicalTrials.gov records NCT07437586, NCT07437547 and NCT07487363, whose sponsor posts example records (NCT07487363 describes itself as fictional); TB-500 definition now cites Ho 2012; registered trials now GHK-Cu 1, not yet recruiting, BPC-157 3, none with posted results, and none of the TB-500 fragment; reviewed by the editorial team.
2026-10-18: diabetic ulcer infection figures limited to the ulcers treated right after debridement, as in Mulder 1994; reviewed by the editorial team.
2026-10-13: links corrected (a link inside a citation or on a generic word removed); no change to the facts.
2026-10-12: links to related entries added; no change to the facts.
2026-10-05: status box re-checked; GHK-Cu registered trials corrected to 2 (NCT07437586, NCT07706361); reviewed by the editorial team.
2026-09-30: status box updated with the FDA advisory committee vote / next regulatory step (Study loop L-2).
2026-09-30: added “What users report” (summarised public anecdote, labelled as such).
2026-09-30: first published after review by the editorial team.