TB-500 myths: what the research does not show
TB-500 is a short synthetic fragment of thymosin beta-4, and almost all of the human research people quote was done with the full-length protein, not with TB-500. This page separates what was studied in the fragment from what was studied in the parent protein, and shows where popular claims overreach.
Findings
- Full-length thymosin beta-4 eye drops reduced dry-eye discomfort by 27% against placebo on a secondary measure in a 72-person randomized trial (Clin Ophthalmol, 2015).
- In 6 of 9 compassionate-use cases of a chronic corneal defect, thymosin beta-4 eye drops were followed by marked healing (2010).
- In mice, thymosin beta-4 improved heart function after an induced heart attack (Nature, 2004).
- The biggest gap: a 2026 orthopaedic review found no controlled human evidence for TB-500 or thymosin beta-4 in muscle, tendon or joint injury.
View product →Myth: TB-500 and thymosin beta-4 are the same thing
False. Thymosin beta-4 is a 43-amino-acid protein the body makes. A 2012 analysis of a product sold as TB-500 identified the acetylated 17-23 fragment of that protein, a seven-amino-acid peptide written Ac-LKKTETQ. A 2026 review in an orthopaedic journal noted that the two are often conflated even though no study has shown they behave the same. The names are related; the molecules are not interchangeable.
Myth: human trials prove TB-500 heals injuries
We found no published human trial of TB-500 itself. The human trials that do exist used full-length thymosin beta-4, in eye, skin and heart research, and none studied sports injuries. The 2026 review put it plainly: direct musculoskeletal evidence for thymosin beta-4 is limited to cell and rodent studies. Healing claims for TB-500 in people rest on borrowed evidence.
Myth: TB-500 repairs a damaged heart
Partly true for the parent protein in animals. In a 2004 mouse study, thymosin beta-4 given after a blocked coronary artery improved heart cell survival and heart function. In 2025, a randomized double-blind trial gave recombinant human thymosin beta-4 or placebo to 96 people after a heart attack. Infarct size was smaller in the subgroup that started early, but across the whole trial the difference was not significant. None of this was done with TB-500.
Myth: thymosin beta-4 research shows TB-500 heals eyes and wounds
The eye work is real, and it is thymosin beta-4 work. In a 2015 phase II dry-eye trial of 72 people, the two primary endpoints did not differ from placebo, but several secondary measures did, including 27% lower discomfort and better corneal staining scores. In nine compassionate-use cases of nonhealing corneal defects, six with one defect type showed marked healing. These results support further eye research on the full protein. They say nothing direct about the fragment.
Myth: TB-500 is safe because the body already makes it
The body makes thymosin beta-4, not TB-500. The fragment is a synthetic peptide, and a 2026 sports medicine review described rigorous human safety data for unapproved repair peptides, TB-500 among them, as scarce. The thymosin beta-4 eye trial reported no adverse events, which is useful for that protein in that form only. Being related to a natural molecule does not establish safety.
Myth: everything sold as TB-500 is the same molecule
Not according to a 2023 analysis. Researchers tested products sold online as TB500 and TB1000 and reported that their content was not consistently what the labels described. This is a reason to know exactly which molecule a research material contains, and it is one more reason TB-500 and thymosin beta-4 findings should not be mixed together.
What TB-500 cannot promise
TB-500 sits on the research record as a fragment of a well-studied protein, with very little work on the fragment itself.
- It cannot promise the results of thymosin beta-4 trials; those used a different molecule.
- It cannot promise faster recovery from muscle, tendon or joint injury; no controlled human study exists.
- It cannot promise heart repair; the human heart trial used the full protein and missed its overall comparison.
- It cannot promise a known human safety profile.
Where the evidence stands
TB-500 is not an approved medicine in Canada for any use, and neither is thymosin beta-4. Full-length thymosin beta-4 has early human trials in eye, skin and heart research. TB-500 has analytical and laboratory studies and no published human trials. TB-500 is available only as a material for laboratory research.
Vistara Labs supplies TB-500 as a laboratory research material. The page above is about the published research, not a claim about our product.
Frequently asked questions
Is TB-500 the same as thymosin beta-4?
No. Thymosin beta-4 is a 43-amino-acid protein. Analyses of material sold as TB-500 identified a seven-amino-acid fragment of it, Ac-LKKTETQ.
Has TB-500 been tested in humans?
We found no published human trial of TB-500. The human trials people cite used full-length thymosin beta-4, mainly in eye and heart research.
What did the thymosin beta-4 eye trials show?
In a 72-person dry-eye trial, the primary endpoints did not differ from placebo, but discomfort was 27% lower on a secondary measure. In nine compassionate-use cases of corneal defects, six showed marked healing.
Sources: Esposito S, Deventer K, Goeman J, et al. Synthesis and characterization of the N-terminal acetylated 17-23 fragment of thymosin beta 4 identified in TB-500, a product suspected to possess doping potential. Drug Test Anal. 2012. PMID 22962027. Tham A, Hodgkins CW, Kennedy JG. Investigational peptides in orthopaedic practice: evidence, safety, and patient counseling for BPC-157, thymosin beta-4, and TB-500. J Am Acad Orthop Surg. 2026. PMID 42937313. Sosne G, Ousler GW. Thymosin beta 4 ophthalmic solution for dry eye: a randomized, placebo-controlled, phase II clinical trial conducted using the controlled adverse environment model. Clin Ophthalmol. 2015. PMID 26056426. Dunn SP, Heidemann DG, Chow CY, et al. Treatment of chronic nonhealing neurotrophic corneal epithelial defects with thymosin beta4. Ann N Y Acad Sci. 2010. PMID 20536469. Bock-Marquette I, Saxena A, White MD, et al. Thymosin beta4 activates integrin-linked kinase and promotes cardiac cell migration, survival and cardiac repair. Nature. 2004. PMID 15565145. Zhang Y, Dong Q, Bian X, et al. Recombinant human thymosin beta 4 improves ischemic cardiac dysfunction in mice and patients with acute ST-segment elevation myocardial infarction after reperfusion. Cardiovasc Res. 2025. PMID 41229390. Mendias CL, Awan TM. Safety and efficacy of approved and unapproved peptide therapies for musculoskeletal injuries and athletic performance. Sports Med. 2026. PMID 41966639. Delcourt V, Garcia P, Chabot B, et al. TB500/TB1000 and SGF1000: a scientific approach for a better understanding of misbranded and adulterated drugs. Drug Test Anal. 2023. PMID 36482504.
All products supplied by Vistara Labs are intended for laboratory research use only. They are not drugs, are not approved for human or veterinary use, and are not intended to diagnose, treat, cure or prevent any condition. Nothing on this page constitutes medical advice or guidance for use in humans.
References
TB-500 and thymosin β4 are not the same molecule. TB-500 is a thymosin β4-derived fragment (Ac-LKKTETQ); the human trials below studied full-length thymosin β4 and are related research rather than trials of TB-500 itself.
- Synthesis and characterization of the N-terminal acetylated 17-23 fragment of thymosin beta 4 identified in TB-500, a product suspected to possess doping potentialAnalytical chemistry: characterises TB-500 as the N-terminally acetylated 17-23 fragment of thymosin β4 (Ac-LKKTETQ), not the intact 43-amino-acid protein.
- A first-in-human, randomized, double-blind, single- and multiple-dose, phase I study of recombinant human thymosin β4 in healthy Chinese volunteersFirst-in-human randomised, double-blind phase 1; 54 single-dose and 30 multiple-dose subjects; recombinant human thymosin β4.
- The effect of thymosin treatment of venous ulcersRandomised, double-blind, placebo-controlled phase 2 trial; 73 patients, eight European centres; topical full-length thymosin β4.
- Thymosin beta 4 ophthalmic solution for dry eye: a randomized, placebo-controlled, Phase II clinical trial conducted using the controlled adverse environment (CAE™) modelRandomised, double-masked, placebo-controlled phase 2 trial; 72 subjects; thymosin β4 ophthalmic solution.
- Thymosin β4 significantly improves signs and symptoms of severe dry eye in a phase 2 randomized trialRandomised phase 2 trial in severe dry eye; 9 patients.
Links open the study record on PubMed so the source can be checked directly. Listing a study is not a claim that its findings apply to any other use, product or route of administration. Research use only.
