Peptide
TB-500
TB-500 (Thymosin Beta-4 fragment)
A synthetic peptide fragment of thymosin beta-4, an endogenous 43-amino-acid protein involved in actin regulation and tissue repair. Anecdotal wound-healing use, no completed human RCT.
Summary Does TB-500 help injuries heal, and is it safe? Show / hide ↓
TB-500 is a synthetic peptide, meaning a lab-made chain of amino acids, related to a natural body protein involved in tissue repair. Research on the full natural protein and regulated versions has shown some safety in small human trials for dry eye and heart problems, but no approved treatment or proven dose. The TB-500 fragment sold online has not been tested in completed human trials. Community use commonly involves 2 to 5 mg injected under the skin once or twice weekly for 4 to 8 weeks, but its benefits and long-term safety are unknown. Because it may affect angiogenesis, the growth of new blood vessels, there is a theoretical concern about helping undiagnosed tumors grow.
What this means for you: There is not enough evidence to buy TB-500 for injury healing. The online product is unregulated, and its safety and effectiveness remain uncertain.
weak evidenceTB-500 sits at the intersection of solid preclinical biology and unregulated biohacker practice. Native thymosin beta-4 (TB4) is a real endogenous protein with well-characterized roles: it sequesters G-actin, modulates actin cytoskeleton dynamics, and participates in tissue repair, angiogenesis, and anti-inflammatory responses across skin, cornea, heart, and muscle.
RegenRx Biopharmaceuticals developed synthetic full-length TB4 (RGN-259 for ophthalmology, RGN-352 for cardiac) and reached phase 2 trials in the mid-2000s for dry eye disease and cardiac ischemia. Both programs produced favorable safety data. RGN-259 has shown modest efficacy in phase 3 dry eye trials as of the mid-2020s but has not yet reached FDA approval. RGN-352 was shelved for lack of definitive cardiac efficacy signals in the trials that were completed.
What is sold in the peptide underground as TB-500 is typically the LKKTETQ fragment or a full-length synthetic version, without regulated manufacturing or purity documentation. Community protocols use 2 to 5 mg subcutaneous once or twice per week for 4 to 8 weeks around a soft-tissue injury. Reports focus on accelerated healing of tendon, ligament, and muscle strains. This maps mechanistically to the TB4 preclinical literature, but the effective dose, injection frequency, and long-term consequences have not been established in human trials.
WADA banned TB-500 for competitive athletes in 2011 alongside other growth factors and tissue-repair agents. The ban did not prevent broad adoption in recreational and professional non-competitive contexts.
Safety data is limited. Phase 2 trials of the regulated pharmaceutical forms tolerated the peptide well. Long-term community use has not surfaced obvious harm signals, but no formal surveillance exists. Theoretical concerns include effects on angiogenesis in the presence of undiagnosed tumors, since angiogenic peptides can accelerate tumor growth if they are present.
Our position: TB-500 sits at Tier 5 for community use. The regulated pharmaceutical program produced Tier 2-3 evidence for narrow indications (dry eye, cardiac) but has not yielded an approved drug or a validated dosing scheme for the fragment sold as TB-500.
TB-500 (a thymosin beta-4 fragment) has an FDA advisory committee vote in its favor and a newly registered cardiovascular trial, but zero completed human efficacy studies as of August 2026.
Verified 2026-08-06. We update this section as PCAC decisions, ClinicalTrials.gov entries, and new peer-reviewed studies land.
FDA / PCAC (July 2026)
Reviewed July 23-24, 2026. The PCAC voted 8-6-1 to recommend TB-500 for the 503A Bulks List, contrary to FDA staff's own briefing document, which recommended against inclusion for all seven reviewed peptides (https://www.fda.gov/media/193343/download). The vote is advisory, non-binding, and no rulemaking has begun (https://validusbio.com/learn/pcac-2026-peptide-vote-results/); STAT News described the panel's action as a win for compounding proponents despite the FDA's own negative staff position (https://www.statnews.com/2026/07/23/fda-panel-okays-peptides-compound-pharmacies-bpc-157-kpv/).
US status
Not FDA approved for any indication; sold almost exclusively as an unregulated research chemical. It was not on FDA's April 2026 Category 2 removal list in the same way as other peptides, but remains outside legal compounding channels pending any future rulemaking.
EU status
Not authorised for human use in EU as of 2026.
Best-supported claim
A phase 1/2 randomized, double-blind, placebo-controlled dose-escalation trial evaluating TB-500 in adults with stable atherosclerotic cardiovascular disease is registered and recruiting under sponsor Hudson Biotech, testing safety, tolerability, pharmacokinetics, and exploratory cardiovascular biomarkers (https://clinicaltrials.gov/study/NCT07487363). Until this trial reports, the strongest support for TB-500 remains its parent molecule thymosin beta-4's role in actin regulation and cell migration in animal wound-healing models, not human outcome data.
Not supported by the evidence base
Peptide vendors market TB-500 for tendon and ligament repair, hair regrowth, and cardiac recovery using language borrowed from unrelated thymosin beta-4 animal studies. A 2026 vendor blog post frames a 2026 human trial as showing "cardiac recovery" results when the registered trial (NCT07487363) has not yet reported any results and is still in the recruiting phase (https://peptiq.io/blog/tb500-cardiac-recovery-human-trials-2026). No published human RCT supports any of these claims; the compound has no completed efficacy data in any indication.
Typical usage
2-2.5 mg subcutaneous injection twice weekly, 4-6 week cycles, in compounding-pharmacy and research-chemical protocols; there is no clinically validated dose because no completed human efficacy trial exists.
Safety
No completed human trial has reported a safety profile; the only registered study (NCT07487363) is in early recruitment and has not posted results (https://clinicaltrials.gov/study/NCT07487363). FDA's July 2026 briefing document lists TB-500 among the peptides with unassessed immunogenicity risk for repeated injectable dosing. Injection-site swelling and redness are the most common adverse reports in self-administration forums, but these are uncontrolled and unverified. Pregnant people, and anyone with active cancer given the actin-remodeling and angiogenic mechanism shared with related thymosin peptides, should avoid it.
Interactions worth flagging
- No formal drug-interaction studies exist
- Theoretical overlap with anticoagulant and antiplatelet agents through cell-migration/angiogenesis pathways
- Unknown interaction when combined with other unregulated peptides in stacking protocols
Three recent studies to know
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TB-500 (Thymosin Beta 4 17-23 Fragment) for Cardiovascular Biomarkers in Stable ASCVD (TBRIDGE-CV)
Phase 1/2 randomized, double-blind, placebo-controlled dose-escalation study now recruiting to test safety, tolerability, pharmacokinetics, and cardiovascular biomarkers in adults with stable atherosclerotic disease.
Read study → -
What the FDA's July 2026 PCAC Peptide Review Decided
PCAC voted 8-6-1 to recommend TB-500 for the 503A Bulks List against FDA staff's own negative recommendation; the vote is non-binding.
Read study → -
FDA Briefing Document, Pharmacy Compounding Advisory Committee Meeting
FDA staff recommended against adding TB-500 to the 503A Bulks List, citing insufficient characterization and unassessed immunogenicity risk.
Read study →
Further reading
Curated external sources for a deeper dive. External links open in a new tab.