Emerging evidence · Grade B
TB-500
TB-500 (Thymosin Beta-4 Fragment)
Score
68 / 100
Half-life
Not established
Class
Thymosin β4 fragment
Status
Investigational
TL;DR
01
A synthetic fragment (amino acids 17–23) of thymosin β4, a natural actin-binding protein involved in cell migration, blood-vessel growth, and wound repair.
02
The TB-500 fragment that athletes use for systemic tendon/muscle healing has no human trials of any kind.
03
The parent protein, thymosin β4, has been tested in small human trials — but for unrelated, mostly topical uses (for example, eye drops for severe dry eye), not systemic musculoskeletal healing.
04
It is not approved as a medicine anywhere and is prohibited in sport by the World Anti-Doping Agency.
05
As with any pro-angiogenic agent, its long-term human safety is unstudied, and consumer supply is research-grade with no purity guarantee.
Human trials (fragment)
None
for TB-500 as marketed
Parent Tβ4 human data
Small / other uses
e.g., dry-eye phase 2
Sport status
WADA-banned
prohibited in competition
Evidence base
Preclinical
cell + animal for healing
Approval
None
research chemical only
Part 01 · How it works
Mechanism.
TB-500 is a piece of thymosin β4, a protein your cells use to reorganize their internal scaffolding (actin), which is central to how cells move, how new blood vessels form, and how wounds close. The theory is that supplying this active fragment could speed healing of tendon, muscle, and other tissue. In cells and animals, thymosin β4 does promote migration and repair — but the specific short fragment sold as TB-500, and its use for systemic injury healing, have never been tested in people.
It's the 'active snippet' of a natural repair protein. In the lab that protein helps cells move and rebuild — but whether injecting the snippet heals a human tendon has never actually been measured.
Actin sequestration
Thymosin β4 binds G-actin and regulates its polymerization, a core driver of cell migration and tissue remodeling.
Angiogenesis & survival
In animal models (e.g., post-infarct heart), promotes endothelial/cardiomyocyte migration and survival via ILK-Akt signaling.
Fragment vs parent
'TB-500' is a synthetic 17–23 fragment; the small human trials that exist used full-length thymosin β4 (e.g., RGN-259) in unrelated indications.
Evidence stage
Preclinical for musculoskeletal healing; no human trials of the marketed fragment.
Part 02 · Dosing & administration
How it's taken.
Community-reported · unregulatedValues below reflect commonly reported community protocols for TB-500. These are anecdotal and unregulated — not clinically validated and not a recommendation. Provided for educational purposes only — this is not medical advice and not instructions for self-administration. Consult your healthcare provider before making any health decision.
Wk 1–6
2.5–5 mg
Loading — 2× weekly
TARGET
Wk 7+
2.5 mg
Maintenance — weekly to biweekly
·
Two conventions circulate: this loading→maintenance mg schedule and a newer ~500 mcg/day protocol — both are community-derived, not from human trials.
·
TB-500 is a synthetic fragment of thymosin β-4; no human pharmacokinetic or efficacy data exist for the marketed fragment.
·
Frequently stacked with BPC-157 with zero controlled data on the combination; research-chemical supply has no dose/purity guarantee.
Need help with reconstitution?
Use the free peptide calculator for dilution, unit conversion, and injection volume.
Part 03 · Safety
Side effects, rare serious events, who shouldn't.
Common
Injection-site reactions
Anecdotal; no controlled incidence data.
Reported
Fatigue / head-rush
User-reported; uncharacterized.
Anecdotal
Serious · rare
Long-term human safety
No human safety dataset for the fragment.
Unknown
Pro-angiogenic / tumor concern
Angiogenesis-promoting mechanism carries a theoretical tumor-feeding concern; unstudied in humans.
Theoretical
Product-quality risk
Research-chemical supply may not match labeled purity or dose.
Source-dependent
Absolute · do not use
×
Active malignancy or history of cancer (thymosin beta-4 may promote angiogenesis and cell migration)
×
Pregnancy or breastfeeding
×
Children under 18
×
Known hypersensitivity to TB-500, thymosin beta-4, or any component
Relative · discuss first
!
Active or prior cancer — pro-angiogenic mechanism, theoretical concern
!
Pregnancy or breastfeeding — no data
!
Competitive athletes — prohibited by WADA
!
Anyone expecting proven human benefit — the fragment is untested in people
Interactions
Anticoagulants (warfarin, heparin, DOACs)
TB-500 promotes wound healing and tissue repair which may alter coagulation dynamics; monitor INR
Moderate
Immunosuppressants
Thymosin beta-4 modulates immune and inflammatory responses; may interfere with immunosuppressive therapy
Moderate
NSAIDs
May have additive inflammation-modulating effects; generally favorable but monitor for reduced healing inflammation
Minor
Labs to monitor
CBC with Differential
Baseline and monthly
Monitor blood counts during tissue healing
CMP (Comprehensive Metabolic Panel)
Baseline and every 3 months
Liver and kidney function
CRP / ESR
Baseline and monthly
Track inflammatory markers during healing
Coagulation Panel (PT/INR)
Baseline
TB-500 affects angiogenesis and wound healing
Part 04 · Evidence
How strong is the evidence?
68
Grade B
Grade B, Emerging — carried by a plausible mechanism and the fact that the parent protein has reached small human trials. But the specific TB-500 fragment and its marketed healing use are untested in humans, and it is banned in sport. Promise, not proof.
Mechanistic plausibility
Thymosin β4's role in cell migration and repair is well established.
76
Preclinical breadth
Solid animal/cell data for the parent protein across cardiac, corneal, and wound models.
70
Human evidence
No trials of the TB-500 fragment; parent-protein human data is small and in unrelated (topical) indications.
40
Safety & tolerability
No serious signals in the small parent-protein trials, but the fragment's human safety is uncharacterized.
68
Independence
Parent-protein work spans several groups; the fragment's healing claims are not independently trialed.
60
Part 05 · Research log
Every study we cite.
We list each study with its methodology, funding source, and our quality grade. Flagged studies aren't dismissed — they're tagged so you can weigh them.
01
2004
Nature Flagged
Thymosin β4 promotes cardiac cell migration, survival, and repair
Thymosin β4 enhanced myocyte migration and survival (ILK-Akt) and improved cardiac function after injury in mice — foundational mechanism, in animals.
Mouse (coronary ligation) + embryonic/postnatal cardiomyocyte models · Landmark mechanism paper for the parent protein, not the TB-500 fragment.
PMID 15565145 ↗
High (preclinical)
02
2015
Cornea Flagged
Thymosin β4 (RGN-259) eye drops for severe dry eye — phase 2 RCT
Topical thymosin β4 improved dry-eye signs and symptoms vs vehicle and was well tolerated — a genuine human trial, but of the full protein, topically, for an unrelated indication.
Randomized, double-masked, placebo-controlled phase 2, 56 days · n = 9 · Small (n=9) trial of topical parent protein; does not speak to systemic TB-500 healing use.
PMID 25826322 ↗
Moderate
Evidence against
What didn't work, and where the evidence is thin.
Every publication is incentivized to tell you a peptide works. We catalogue the null results, failed trials, and mechanism limits we found in the same literature — so you can weigh them against the upside, with your provider.
01
The marketed fragment has no human trials — the human data is a different molecule and use
Mechanism limit Cornea · 2015
The only human RCTs in this space used full-length thymosin β4 delivered topically for dry eye — not the systemic TB-500 fragment injected for tendon or muscle healing. Those are different molecules, routes, and indications.
What this means: Pointing to 'thymosin β4 human trials' to justify TB-500 conflates two different things. For TB-500 as actually used, the human evidence is zero.
PMID 25826322 ↗
02
Banned in sport and pro-angiogenic
Safety signal Nature (mechanism) · 2004
TB-500 is on the World Anti-Doping Agency prohibited list, and its core mechanism promotes angiogenesis — a healing signal that carries a theoretical concern for feeding abnormal tissue. Long-term human safety is unstudied and supply is unregulated.
What this means: Beyond the missing efficacy data, athletes face sanctions and everyone faces an uncharacterized long-term risk profile.
PMID 15565145 ↗
Part 06 · Cost & access
Where it's available, at what price.
United States
Not approved
Not an approved drug; sold as a research chemical. Prohibited in sport. No legal consumer medicine.
Grey-market; unregulated
European Union
Not approved
No approved product; prohibited in sport.
N/A
United Kingdom
Not approved
No approved product; prohibited in sport.
N/A
Canada
Not approved
No approved product; prohibited in sport.
N/A
The Peptide Column takes no affiliate commission from any source. TB-500 is not approved as a medicine anywhere and is banned in sport by WADA; material sold to individuals is research-grade and unregulated, and its healing benefits are unproven in people. We link only to clinician-directed care, never to sellers.
Part 07 · Your appointment
Questions to bring.
01
Are there any human clinical trials of Thymosin Beta-4 or TB-500 underway that I might be eligible for?
02
Given TB-500's pro-angiogenic properties, is there any concern given my personal health history?
03
How does TB-500 compare to BPC-157 for my specific injury or recovery goal?
04
Is there an evidence-based alternative with completed human trials for my condition?
References
Every citation, numbered.
Citation list. For our editorial read of each study — including bias flags and quality grades — see the Research log above.
- 01.
- 02.
- 03.