TB-500
Thymosin Beta-4 fragment
The Ground Truth Score
four plain questions, never one numberAnimal data, modest signal
Bottom line
Strong tissue-repair data in animals and essentially no human evidence, for efficacy or safety, on the synthetic fragment people actually inject.
Does the science back it?
Do real people feel it?
Is it safe?
Could it be placebo?
Can you legally get it?
Advisory: yesRecommended, not legal yetAn FDA advisory committee recommended this for the 503A Bulks List in July 2026. Read that precisely: it is a recommendation, not a rule. Nothing changed about what is legal, FDA still has to run notice-and-comment rulemaking, and it can decline. As of October 12, 2026 it is still bought the same gray-market way it was before the vote.
Recommended for the 503A Bulks List by FDA's Pharmacy Compounding Advisory Committee, 8-6 with one abstention, on July 23, 2026, for wound healing. FDA's briefing proposed not adding it and found no human exposure data for the fragment. The nominators withdrew its Category 2 listing in April 2026, so it sits in no FDA category. The vote is advisory; as of October 12, 2026 FDA has published no proposed rule, so it is still not lawfully compoundable. Also named on WADA's 2026 list (S2.3).
Legal status as of 2026-10-12. This is a separate axis from the grades above, and it does not move them. A vote about who may legally prepare a compound is not evidence that the compound works.
"Do real people feel it?" is anecdote, not proof, weighted up because the science is thin, never because it beats a trial. And "could it be placebo?" is not an insult: if you feel better, that's real to you. The point is only to know whether you're paying peptide prices for an expectation.
Why is the evidence this thin? It's mostly economics →
Dose at a glance
full dosing ↓Reported, not prescribed.
Reported, not prescribed. Verify your vial and your math.
First documented human use
No controlled human trial of TB-500 itself has ever been published. The parent molecule, Thymosin Beta-4, was tested as a topical gel in a Phase 2 venous-ulcer trial (73 patients, published 2010) and as an IV infusion in a placebo-controlled Phase 1 in healthy volunteers.
The pitch
What people claim it does
Stated plainly and neutrally, exactly as you'll hear it. We grade each one below.
- Promotes tissue repair, flexibility and recovery after muscle and tendon injury.
- Reduces inflammation and may aid cardiac tissue repair after a heart attack.
- Frequently stacked with BPC-157 as a 'healing' combination.
The data behind each bullet
What actually backs it
Promotes tissue repair and recovery.
Repair effects are documented in animal models (muscle, tendon, corneal, cardiac). There is no published human efficacy trial of TB-500.
Philp & Kleinman 2010, Tβ4 animal tissue-repair review ↗Aids cardiac repair after heart attack.
Animal post-MI data is the basis. A 2025 randomized trial of full-length recombinant thymosin beta-4 in 96 heart-attack patients found a smaller infarct only in those dosed within 8 hours; the overall difference was not significant. No heart-repair data exist for the TB-500 fragment itself.
Bock-Marquette et al., Nature 2004, post-MI cardiac repair (mouse) ↗Full-length thymosin beta-4 reduced infarct size after a heart attack only in early-treated patients.
96-patient randomized, placebo-controlled, double-blind trial of recombinant full-length human thymosin beta-4 (not TB-500). Infarct was smaller only in the subgroup dosed within 8 hours of PCI; the overall difference was not significant. Grade D for TB-500 because the fragment was not tested.
Zhang et al. 2025, Cardiovasc Res ↗Topical thymosin beta-4 gel was safe in a Phase 2 venous-ulcer trial.
73 randomized patients, dose-escalation, parent protein, topical route. The authors said the 0.03% dose may have the potential to accelerate healing, and about a quarter of patients healed within 3 months. Does not transfer to injected TB-500.
Guarnera et al. 2010, Ann N Y Acad Sci ↗Safe to use.
Phase 1 of the PARENT compound (Tβ4) showed no serious adverse events at 42–1260 mg over 14 days. No safety data exists for the synthetic fragment TB-500 in humans, and long-term effects are unknown.
Ruff et al. 2010, Tβ4 Phase 1 (IV, 42-1260 mg, no SAE) ↗Prove it
Can you tell if it's working?
The honest test: if it's working, is there any objective way to see it, a blood marker, a scan, a wearable? For a lot of peptides the answer is no, and that's worth knowing before you spend on labs or gear.
No objective way to prove TB-500 works, track the specific injury (pain, range of motion, strength, return to activity, or targeted ultrasound/MRI of that exact lesion), not any lab, blood, or wearable.
Bloodwork
Nothing on a routine panel confirms this one. Anyone who says otherwise is guessing.
TB-500 is a synthetic fragment of thymosin beta-4, an actin-sequestering peptide that acts locally at injury sites to promote cell migration, angiogenesis, and tissue repair. It produces no systemic hormone, enzyme, or metabolite that a routine panel measures, so a working dose does not register in standard bloodwork.
Read this before you spend on labs
Routine bloodwork cannot confirm TB-500 is working. Its action is local tissue repair (tendon/ligament/muscle/soft tissue), and there is no published human efficacy trial and no LabCorp/Quest analyte that tracks its biological effect. Reported benefits are largely subjective recovery feel, which makes placebo very plausible. Judge progress by functional endpoints (pain, range of motion, return to activity) or targeted imaging of the specific injury, not blood. Inflammatory markers like CRP/ESR are far too nonspecific and confounded to attribute any change to this peptide, so do not use them as a proxy.
Bottom line
TB-500 (a synthetic thymosin beta-4 fragment) is marketed for localized tissue repair, has no published human efficacy trial, and produces no systemic hormone or metabolite that any orderable lab or consumer device measures. Its claimed effects are local healing and recovery, which have no validated objective proxy on a wearable, DEXA, CGM, VO2max, urine, or stool test, nothing on those modalities changes as a signature of this peptide working, and any trend there is confounded by training, sleep, or illness, not confirmation. The only honest way to gauge whether it is helping is injury-specific: functional endpoints (pain scores, range of motion, strength, return to activity) or targeted imaging (ultrasound/MRI) of the exact tendon, muscle, or ligament being treated, compared before and after. Those are localized clinical assessments, not standing quantified-self trackers. Blood adds nothing here either (tier=none). Bottom line: there is no accessible objective tracker for TB-500 across any modality, anyone selling a biomarker for it is guessing.
Logging baseline vs retest is the whole game. The Truth Tracker is our free log for bloodwork, DEXA, genetics, and wearable data, bring your own numbers.
How to track it →Mechanism
How it's assumed to work
Assumed · theoretical pathway
Assumed, not proven in humans: TB-500 is a fragment of thymosin β4 that binds actin and is thought to promote cell migration, blood-vessel growth, and tissue repair. Shown in animals; unproven in people, and the sold fragment differs from the studied molecule.
Dosing & handling
What users and clinicians report
Reported, not prescribed. Reported protocols vary several-fold between sources. Loading: about 750 mcg–2.5 mg subcutaneously, twice weekly for 4–6 weeks (some community guides go to 5 mg). Maintenance reports range from about 750 mcg–1 mg twice monthly up to 2–2.5 mg once weekly. Dr. Bakri describes a similar loading-then-maintenance pattern. Commonly co-administered with BPC-157.
There is no established clinical dose because there is no clinical trial. Every number here is community or authority report, not medicine.
Timing & food
A loading phase (~2×/week) then maintenance; timing relative to food isn't established. The infrequent schedule comes from the longer assumed duration of action.
Half-life
Longer than BPC-157. The parent molecule (thymosin β4) shows a human half-life around 1–2 hours, plus an assumed tissue-residence effect, which is why it's dosed less often, typically a ~2×/week loading phase.
Reconstitution sensitivity
Standard peptide fragility, refrigerate the reconstituted vial, don't shake, replace BAC water ~28 days. Worth knowing: the marketed 'TB-500' fragment is not the full molecule most human safety data refers to.
Real-world signal
What people actually report
Anecdote, not proof, weighted because the science is thin. Here's the record, graded on volume, consistency, and how credible the sources are.
Volume
Moderate, but it rarely travels alone; most reports live inside the BPC-157 'Wolverine' stack.
Consistency
Recovery reports are positive but almost totally confounded by the BPC-157 co-stack, with credible 'did nothing' reports recurring.
Source credibility
Trust the mixed-outcome forums (MESO-Rx, equine boards); discount the guide sites that supply the suspiciously precise stats.
- Usually reported as half of a 'healing stack' with BPC-157, so isolated TB-500 reports are scarce.
- Users describe better flexibility and recovery, but in vague terms.
- Few specific side-effect reports, which reflects how little it's been used carefully, not proven safety.
Placebo risk, High
Reported benefits are almost entirely subjective recovery feel, and it's run inside stacks, so attribution to TB-500 specifically is weak and placebo is very plausible.
Risk panel
What could go wrong
Adverse events
No reports tied to TB-500 alone: FDA's July 2026 review found no human exposure data for the fragment and no adverse-event reports (one report involved a BPC-157 plus TB-500 product). Absence of reports is not evidence of safety here.
Theoretical concerns
As a pro-angiogenic, pro-migratory peptide, the same theoretical tumor-growth concern that applies to BPC-157 applies here, and is even less studied.
Contraindications
Active or suspected malignancy (theoretical). Pregnancy untested.
Honest unknowns
Nearly everything in humans: efficacy, dose, long-term safety, and whether the injected fragment behaves like the parent protein at all.
Confound watch
TB-500 is almost always run alongside BPC-157 and a rehab block. When the combo 'works,' there is no way to credit TB-500 specifically, the cleanest attribution any honest user can make is 'something in the stack, or time.'
History
Discovery → first use → status
Update: an FDA advisory panel voted in favor of this one on July 23-24, 2026
The FDA's Pharmacy Compounding Advisory Committee voted to recommend adding this to the 503A Bulks List, meaning compounding pharmacies could legally prepare it. The vote: 8-6, with one abstention. Now read the fine print, because it matters more than the headline. The vote is advisory and changes nothing today: FDA still has to go through formal rulemaking, which can take a year, and it has overruled its own panels before. As of October 12, 2026, eleven weeks after the vote, FDA has not published a proposed rule, so this is still not lawfully compoundable. FDA's own scientists recommended AGAINST adding it, citing thin human evidence and unassessed immunogenicity risk, and the committee voted the other way. That committee is also not neutral: it was reconstituted with recent appointees, and several work at or run clinics that sell peptide treatments. And none of this is a finding that the compound works. A compounding-eligibility vote is not drug approval, and it is not evidence. Our grade here is unchanged, because the evidence did not change.
Vote tallies as reported by the press (STAT, McDermott Will and Schulte); FDA has not posted tallies, minutes or a transcript, and its meeting materials are on its meeting page. Rechecked October 12, 2026: no proposed rule in the Federal Register through October 8, and docket FDA-2025-N-6895 closed July 22, 2026. Nothing here is final, so check the current rule before acting.
FDA, PCAC meeting, July 23-24 2026 ↗- 1960s–80sThymosin Beta-4, the parent protein, identified as an actin-regulating peptide.
- 2009Phase 2 trial of topical Tβ4 gel for venous stasis ulcers (73 patients) finished; results published in 2010.
- 2010sTB-500, a synthetic fragment, spreads through veterinary and gray-market athletic use.
- Sept 2023Placed in FDA Category 2.
- Apr 2026Dropped from Category 2 after its nominators withdrew their nominations; not placed in any other category.
- Jul 23 2026PCAC voted 8-6 (1 abstention) to recommend TB-500 for addition to the 503A Bulks List. Evaluated for wound healing; FDA staff recommended against. Advisory only: no FDA proposed rule as of Oct 12 2026, and no evidence grade moves on a compounding vote.
Verification
The COA standard, applied
Injected, so the BPC-157 standard applies in full: a batch COA with HPLC purity ≥98%, mass-spec identity, and LAL endotoxin, from an independent lab, never the vendor's own lab. Identity testing matters especially here: a peptide fragment is easy to mislabel or substitute.
The full verification standard →Sources
Where this comes from
The four lenses reflect the evidence and the real-world record as of the last review and will change as data arrives. Real-world signal and reported feedback are anecdote, not proof. Nothing here is medical advice or a prescription.