What it is
TB-500 is a lab-made peptide sold for its supposed tissue-repair and recovery effects. Chemically, the 'TB-500' name refers to a short synthetic fragment (Ac-LKKTETQ) copying the central actin-binding region of Thymosin Beta-4 (Tβ4), a 43-amino-acid protein your body makes naturally that is involved in cell movement, wound repair, and inflammation control.
In practice the research-peptide market blurs the line: many products labeled 'TB-500' are described as, or sold as, the full Tβ4 protein rather than the short fragment. This matters because the human clinical data that exists was generated with full-length Tβ4, not the TB-500 fragment — so you can't cleanly transfer those findings to a vial labeled 'TB-500.'
It is sold strictly 'for laboratory research use only.' It is not an approved medicine, and it is not a dietary supplement.
How it works
Thymosin Beta-4's best-understood job is binding G-actin, a building-block protein cells use to build their internal scaffolding. By regulating actin, Tβ4 helps cells migrate into a wound, which is a key early step in healing. In animal and lab studies it also appears to promote angiogenesis (new blood-vessel growth), reduce inflammation, and blunt apoptosis (programmed cell death), which is why researchers describe it as a broad 'master regulator' of repair rather than a single-target drug.
Interestingly, recent research suggests some of Tβ4's wound-healing activity may come from a small breakdown product (the metabolite Ac-LKKTE) rather than the parent molecule — meaning how the peptide is processed in the body may matter as much as the peptide itself. Much of this mechanism work is preclinical, so the human-relevant details remain uncertain.
What people research it for
Faster skin/wound repair
Animal studiesIn a rat full-thickness wound model, Thymosin Beta-4 increased reepithelialization by 42% at day 4 and up to 61% at day 7 vs saline, with more wound contraction, collagen and new blood vessels. Full-length Tβ4, animal model.
Corneal / eye-surface healing
Early human dataThe one setting with real human data: full-length Tβ4 (as RGN-259 eye drops) improved signs and symptoms of severe dry eye in a small phase 2 trial and helped some neurotrophic keratopathy patients — but a later European phase 3 missed its primary endpoint.
Muscle, tendon and soft-tissue recovery
Preclinical / theorizedThe popular 'injury recovery' use is almost entirely extrapolated from animal repair studies and community reports. A recent scoping review found direct TB-500 (fragment) evidence limited to essentially a single study; most literature is preclinical.
Reduced inflammation
Animal studiesTβ4 lowers inflammatory signaling and cell death in animal cardiac, neural and skin injury models, contributing to its repair effects — not demonstrated as a standalone anti-inflammatory therapy in humans.
What the research actually shows
The strongest and most consistent findings are preclinical: across rat and mouse models, Thymosin Beta-4 accelerates skin, corneal, cardiac and neural repair. The classic wound-healing paper reported large gains in reepithelialization (up to 61% at day 7) and contraction in rats.
Human evidence is narrow and specific to the eye. Full-length Tβ4 as RGN-259 ophthalmic drops showed statistically significant improvements in a small (9-patient) phase 2 dry-eye trial with no serious adverse events, and helped a majority of patients in one phase 3 neurotrophic-keratopathy trial — though a separate European phase 3 failed its primary endpoint.
Two big honesty points: (1) that human data used the full natural protein, not the TB-500 fragment sold to researchers; and (2) there are essentially no controlled human trials of TB-500 for muscle, tendon or systemic 'recovery,' which is its most-marketed use. Reviewers describe the overall literature as largely preclinical and unevenly distributed.
Research handling & storage
TB-500 is typically supplied as a lyophilized (freeze-dried) white powder in sealed vials, most commonly 2 mg or 5 mg. In research settings it is reconstituted with bacteriostatic water (sterile water containing 0.9% benzyl alcohol as a preservative), added slowly against the vial wall and swirled rather than shaken to avoid degrading the peptide.
Lyophilized vials are generally stored refrigerated or frozen and protected from light; once reconstituted, the solution is kept refrigerated and used within a few weeks. Reported half-life is relatively short (on the order of hours), which is one reason community protocols use intermittent dosing — but these are literature/community-reported handling notes for research use, not medical instructions or a dosing recommendation.
Safety & cautions
TB-500 is not approved by the FDA (or any major regulator) for human use, and no product on the research market has undergone the safety review a medicine requires. Purity, sterility and actual peptide identity vary between vendors, and injectable use of unregulated products carries infection and contamination risks. The limited human safety data (dry-eye eye drops) was for full-length Tβ4 given topically, not for injected TB-500, so it does not establish safety for how the peptide is commonly used.
There is a specific, well-founded theoretical concern that potent pro-angiogenic, pro-migration signaling could be undesirable in the presence of cancer, and long-term human safety is simply unknown. It is also banned in sport: WADA prohibits 'Thymosin-β4 and its derivatives (e.g. TB-500)' at all times under Section S2 (growth factors). Athletes in tested sport who use it risk sanctions.
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Frequently asked questions
Is TB-500 FDA approved?
No. It is not approved for any medical use and is sold only 'for laboratory research use only.' It is not a supplement or a medicine.
Is there human evidence it works?
Only narrowly, and with a caveat: full-length Thymosin Beta-4 (as RGN-259 eye drops) has early human trial data for dry eye and corneal healing. There is essentially no controlled human trial evidence for the TB-500 fragment used for muscle/tendon/injury recovery — that use rests on animal studies and anecdote.
Is TB-500 the same thing as Thymosin Beta-4?
Not exactly. 'TB-500' technically means a short synthetic fragment (Ac-LKKTETQ) of Tβ4, but many products sold as TB-500 are described as the full 43-amino-acid protein. The two differ in chemistry, pharmacokinetics and which evidence applies.
Is TB-500 banned in sports?
Yes. WADA lists Thymosin-β4 and its derivatives, explicitly naming TB-500, as prohibited at all times under Section S2. Tested athletes risk a doping violation.
What are the main safety concerns?
Unapproved status and unregulated product quality (purity/sterility), unknown long-term effects, a theoretical cancer-growth concern from its pro-angiogenic activity, and infection risk from injecting non-pharmaceutical products. Long-term human safety is not established.
Sources
- Malinda et al., FASEB J — 'Thymosin beta4 accelerates wound healing' (rat model)
- Sosne et al., PubMed — Phase 2 trial: Thymosin β4 (RGN-259) for severe dry eye
- MDPI Applied Sciences — Scoping review: Thymosin Beta-4 and TB-500 in tissue healing and musculoskeletal repair
- BSCG — TB-500 status, risks, and WADA/anti-doping bans in sport
Last reviewed 2026-07-07. This guide is educational and research-focused — not medical advice. TB-500 products referenced on PeptidePub are sold by third parties as materials for laboratory research use only, not for human or animal consumption.
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