Peptide guide
KLOW: what it is and what the research actually shows
KLOW is a name research-chemical sellers use for one vial that mixes four peptides: GHK-Cu, BPC-157, TB-500 and KPV. It is not one peptide, and no published study has tested the four together.
Byline: PeptideGauge Editors. Sources checked 2026-08-22. Every claim below links to its PubMed record or FDA page.
Quick facts
- What is in it
- GHK-Cu
- BPC-157
- TB-500 (thymosin beta-4 fragment)
- KPV
Three sellers we checked on 2026-08-22 list the same four peptides and describe GHK-Cu as the largest share. We did not test any product, so we cannot say what any given vial actually contains.
Seller pages that state this:
- Studied for
- Skin and wound repair (GHK-Cu, TB-500), gut and tendon healing (BPC-157), gut and skin inflammation (KPV). Almost all of it in cells or animals.
- Studies of the blend itself
- None. A PubMed search on 2026-08-22 for the four-peptide combination found no study that gave them together.
- Human evidence, part by part
- GHK-CuLimited1 human study foundBPC-157Limited2 human studies foundTB-500 (thymosin beta-4 fragment)Limited2 human studies foundKPVNone0 human studies found
- Approved by the FDA?
- No. See where it stands.
What this page does
- Says what sellers mean by the name
- Lists what was studied, in whom, and what was found
- Grades each study: cells, animals, small human study, or trial
- Links every claim to PubMed or FDA
What it will not do
- Tell you how much to use or how often
- Tell you how to mix it or how much water
- Tell you where to buy it
- Guess where the research is silent
How to read the grades
Each study gets a tag. Cells in a dish means it never touched a living animal. Animals means mice or rats, usually. Small human study means a handful of people with no comparison group. Human trial means people were randomly split into treated and untreated groups, which is the only kind that can show an effect is real. Review and Systematic review sum up other studies. The full rule is on How we check.
GHK-Cu
A small natural peptide (three amino acids) that binds copper. Found in human blood; levels fall with age. Studied mostly for skin and tissue repair.
Human evidence: Limited. 1 human study found in our search.
What has been studied
| Who or what was studied | What was found, and the catch | Source |
|---|---|---|
| Review | Reviews cell and gene studies suggesting GHK-Cu nudges pathways tied to tissue repair and inflammation. Limit: Written by the peptide's discoverer; mostly lab-dish and gene data, no controlled patient outcomes. | Pickart 2018 PMID 29986520 |
| Review | Summarizes lab evidence that GHK can raise collagen and other skin-structure molecules. Limit: Same author group; no controlled human trial evaluated. | Pickart 2015 PMID 26236730 |
| Human trial n = 13 people | After laser skin resurfacing, a copper-peptide cream did not beat control on measured redness or wrinkles; patients did report liking it more. Limit: Thirteen people, a skin cream, and the only win was a satisfaction score. | Miller 2006 PMID 16847171 |
| Review | Questions whether GHK in skin products reaches where it would need to act, and calls the effectiveness data thin and inconsistent. Limit: Narrative review. | Mortazavi 2025 PMID 39963574 |
Safety signals in the studies
- No skin reactions flagged in the one small trial (a cream, not an injection). PMID 16847171
- We found no published human safety data for injected GHK-Cu.
BPC-157
A lab-made peptide (15 amino acids) copied from a piece of a protein in human stomach fluid. Studied mostly in rats for gut and tendon healing.
Human evidence: Limited. 2 human studies found in our search.
What has been studied
| Who or what was studied | What was found, and the catch | Source |
|---|---|---|
| Systematic review n = 36 studies, 1 human | Of 36 studies, 35 were in animals, where healing of tendon, ligament, muscle and bone improved. The one human study was small and retrospective. Limit: Review says plainly: no clinical safety data exist for BPC-157. | Vasireddi 2025 PMID 40756949 |
| Small human study n = 16 people | Patients given BPC-157 for knee pain mostly said they felt better when phoned months later. Limit: No control group, no imaging, relies on memory by phone. | Lee 2021 PMID 34324435 |
| Small human study n = 12 people | Women with stubborn bladder pain reported big improvements after BPC-157; no side effects were reported. Limit: Twelve people, one clinic, no comparison group, self-reported outcome. | Lee 2024 PMID 39325560 |
| Review | Rodent studies suggest faster healing of tendon, ligament and muscle. Limit: Animal data only; not confirmed in people. | Gwyer 2019 PMID 30915550 |
| Review | Describes proposed ways BPC-157 might help wounds heal, such as nitric oxide signaling and new blood vessels. Limit: Mechanisms come from rat models. | Seiwerth 2021 PMID 34267654 |
Safety signals in the studies
- Systematic review: animal studies show no harm across organs, but there is no human safety data. PMID 40756949
- No adverse events in a 12-person pilot. PMID 39325560
TB-500 (thymosin beta-4 fragment)
Thymosin beta-4 is a natural protein in almost every cell that helps cells move and rebuild. TB-500 is the name sellers use for a lab-made piece of it. Most studies used the full protein, not the fragment.
Human evidence: Limited. 2 human studies found in our search.
What has been studied
| Who or what was studied | What was found, and the catch | Source |
|---|---|---|
| Human trial n = 73 people | In people with leg ulcers, thymosin beta-4 was as safe as placebo and a minority of treated patients healed fully. Limit: One mid-stage trial; benefit over placebo was modest. | Guarnera 2010 PMID 20536470 |
| Review | Summarizes thymosin beta-4's role in cell movement and tissue repair and lists trials then under way. Limit: Author helped develop the compound. | Goldstein 2012 PMID 22074294 |
| Review | Animal studies suggest faster skin wound healing and less inflammation. Limit: Large controlled human trials for skin wounds are missing. | Kleinman 2016 PMID 27450738 |
| Review | Animal studies suggest less heart damage after injury. Limit: No human heart outcome trials cited. | Pipes 2016 PMID 27450736 |
| Review | Explains how thymosin beta-4 binds actin, the cell's scaffolding protein. Limit: Structure only, not a treatment study. | Bubb 2003 PMID 12852258 |
Safety signals in the studies
- Safety comparable to placebo in a 73-person trial of the full protein. PMID 20536470
- We found no human study of the shorter TB-500 fragment that sellers actually offer.
KPV
A three-amino-acid piece of a natural hormone (alpha-MSH). Studied in mice and cells for calming gut and skin inflammation.
Human evidence: None. 0 human studies found in our search.
What has been studied
| Who or what was studied | What was found, and the catch | Source |
|---|---|---|
| Animals | In two mouse models of bowel inflammation, KPV reduced colitis severity. Limit: Mice only; paper notes KPV is hard to deliver and unstable. | Kannengiesser 2008 PMID 18092346 |
| Animals | A gut transporter moved KPV into intestinal cells, and that uptake went with less inflammation. Limit: Mice only. | Dalmasso 2008 PMID 18061177 |
| Animals | KPV packed into nanoparticles eased mouse colitis better than KPV alone. Limit: Results may owe as much to the nanoparticle as to KPV. | Xiao 2017 PMID 28143741 |
| Animals | KPV reduced inflammatory cell build-up in mice about as well as the full hormone. Limit: Mechanism study, not a disease outcome. | Getting 2003 PMID 12750433 |
| Cells in a dish | In human skin cells in a dish, KPV switched on an anti-inflammatory signal. Limit: Cells only. | Elliott 2004 PMID 15102092 |
Safety signals in the studies
- No human study found. FDA says it has no human exposure data for KPV (see regulatory note).
Where it stands with regulators
- All four peptides appear on the FDA's list of bulk drug substances nominated for compounding and then withdrawn. FDA's stated concerns: possible immune reactions for some routes and peptide-related impurities (BPC-157, TB-500, GHK-Cu); for KPV, FDA says it has found no human exposure data at all. None of the four is an FDA-approved drug. Page last updated 2026-04-22. Source
- A 2025 systematic review notes BPC-157 is not approved by any regulator and is banned in professional sport. Source
What is missing
No study of the blend itself. No large human trial of any part in the form that is sold. No long-term safety data in people for any part. Where this page says "limited," read it as "a few small studies that cannot settle the question."
Common questions
Is KLOW one peptide?
No. It is a seller's name for a mix of four peptides in one vial. Each one has its own research; the mix has none.
Has KLOW been tested in people?
Not as a blend. Of the four parts, KPV has no human studies at all, and the other three have a handful of small ones, mostly skin creams, eye drops or the full thymosin protein rather than what is sold.
Is it FDA approved?
No. All four peptides are on the FDA's list of compounding substances that were nominated and withdrawn over safety questions.
Will this page tell me how much to use?
No. We do not publish amounts or schedules for any peptide. That belongs with a licensed doctor.
Sources
- Bubb (2003). PMID 12852258
- Dalmasso (2008). PMID 18061177
- Elliott (2004). PMID 15102092
- Getting (2003). PMID 12750433
- Goldstein (2012). PMID 22074294
- Guarnera (2010). PMID 20536470
- Gwyer (2019). PMID 30915550
- Kannengiesser (2008). PMID 18092346
- Kleinman (2016). PMID 27450738
- Lee (2021). PMID 34324435
- Lee (2024). PMID 39325560
- Miller (2006). PMID 16847171
- Mortazavi (2025). PMID 39963574
- Pickart (2015). PMID 26236730
- Pickart (2018). PMID 29986520
- Pipes (2016). PMID 27450736
- Seiwerth (2021). PMID 34267654
- Vasireddi (2025). PMID 40756949
- Xiao (2017). PMID 28143741
FDA list of bulk drug substances nominated for compounding and withdrawn, last updated 2026-04-22: fda.gov.
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