TB-500
Thymosin Beta-4 · Thymosin β4 · Tβ4 · TMSB4X · Ac-LKKTETQ
Actin-regulating thymosin peptide used for soft-tissue repair and range of motion.
Typical dose
2.5 mg
2x weekly during loading, then once every 1-2 weeks for maintenance
Range
2–5
mg
Half-life
2 h
see Dosing
Evidence
Early human
Subcutaneous · Intramuscular
What it is
Thymosin beta-4 is a 43-amino-acid peptide found in essentially every human cell and in high concentration in platelets and wound fluid. It is the main intracellular actin-sequestering protein, and it is released at sites of injury where it promotes cell migration, new blood-vessel formation and a shift away from scar-type healing.
There is a labelling problem worth understanding before you buy. "TB-500" strictly refers to a short synthetic fragment, the acetylated 7-mer Ac-LKKTETQ (roughly 889 Da), which is the actin-binding motif from positions 17-23. In practice most research-chemical vendors sell full-length 43-amino-acid Tβ4 under the TB-500 name. The two are not interchangeable on a milligram basis, and vendors frequently do not say which one is in the vial. Ask for the certificate of analysis and look at the stated molecular weight.
Unlike BPC-157, Tβ4 has actually been into human trials — phase 1 and 2 work in dry eye, corneal wounds, epidermolysis bullosa and cardiac injury, plus a first-in-human IV pharmacokinetic study. None of that covers the tendon and joint use the lifting world buys it for, and dosing there is entirely community-derived.
How it works
The central LKKTETQ motif binds monomeric G-actin and controls how much of it is available to polymerise into filaments. Regulating that pool is what lets cells reorganise their cytoskeleton and migrate, which is the first step in closing a wound and in repopulating damaged tendon or muscle with repair cells.
On top of that it upregulates VEGF-driven angiogenesis, promotes endothelial cell migration and differentiation, and dampens inflammatory signalling in part by promoting autophagy in macrophages. The practical result reported in animal models is faster closure with less fibrosis, which is the basis for the flexibility and range-of-motion effects people describe.
Dosing
If your vial is the short Ac-LKKTETQ fragment rather than full-length Tβ4, these milligram figures do not transfer — the fragment is about one fifth the molecular weight, so the same mass is roughly five times the molar dose.
Reconstitution calculator
Pre-loaded with TB-500’s vial size, water volume and typical dose. Change anything.
Typical: 2.5 mg · range 2–5
Draw to
50 u
0.5 mL · 2.5 mg
Concentration
5 mg/mL
50 mcg per unit
Doses per vial
2
Vial lasts
7 days
CheckThe draw fills more than 90% of the barrel. Workable, but there is no room for an air bubble or a correction.
Once mixed
Refrigerate at 2-8 C and use within 4-6 weeks; keep it out of the fridge door where temperature swings are worst.
Run the bacteriostatic water slowly down the vial wall and swirl until clear; Tβ4 is a long peptide and shaking will shear it. 5 mg in 1 mL gives 5 mg/mL, so a 2.5 mg dose is 0.5 mL, or 50 units on a U-100 insulin syringe — use 2 mL instead if you would rather inject a smaller mass per unit of volume.
Storage
Before mixing
Sealed and dry at 2-8 C for two years or more; it tolerates short periods at room temperature during shipping but should go back in the fridge on arrival.
After mixing
Refrigerate at 2-8 C and use within 4-6 weeks; keep it out of the fridge door where temperature swings are worst.
Reported benefits
- ▪Promotes cell migration and angiogenesis into injured soft tissue
- ▪Reduces fibrotic scar formation in animal wound and cardiac models
- ▪Commonly reported to improve joint range of motion and reduce stiffness
- ▪Anti-inflammatory action independent of immunosuppression
- ▪Systemic rather than local action, so injection site does not have to match injury site
- ▪Twice-weekly dosing schedule, far less frequent than most repair peptides
Side effects
- ▪Injection-site stinging, redness or a small lump
- ▪Transient fatigue or a flu-like feeling for a day after injecting, most common during loading
- ▪Head rush or light-headedness shortly after the shot
- ▪Occasional reports of temporary joint aching before symptoms improve
- ▪Theoretical tumour-growth risk from angiogenic and cell-migration activity
- ▪No long-term human safety data at repeated multi-milligram doses
Do not use if
- ▪Active or previously treated cancer — Tβ4 promotes both angiogenesis and cell migration
- ▪Pregnancy and breastfeeding — no data
- ▪Tested athletes, since it is explicitly prohibited in sport
- ▪Known hypersensitivity to the peptide or to benzyl alcohol
Evidence level — Early human
Small or early-phase human studies only.
Not approved as a drug in any market, sold as a research chemical, and prohibited at all times in WADA-tested sport.
Commonly run with
BPC-157
Gastric-juice-derived pentadecapeptide studied for tendon, ligament and gut healing.
250 mcg · 1x daily (some split into 2x daily during an acute injury)
GHK-Cu
Copper-carrying tripeptide studied for collagen synthesis, wound repair and skin remodelling.
2 mg · 1x daily
KPV
Tripeptide tail of alpha-MSH used to damp gut and skin inflammation.
500 mcg · 1x daily
TB-500 FAQ
How do I know whether I bought the full peptide or the 7-mer fragment?+
Check the certificate of analysis for molecular weight. Full-length thymosin beta-4 is about 4964 Da; the Ac-LKKTETQ fragment is about 889 Da. If the vendor cannot produce a COA or gives you no molecular weight, you do not know what you are dosing.
Why is it dosed twice a week if the half-life is only a couple of hours?+
Because the effect is on cell behaviour — migration, vessel growth, gene expression — and those changes persist well beyond the peptide's residence in plasma. The twice-weekly schedule comes from animal work and community practice, not from a pharmacokinetic argument.
Is it worth stacking with BPC-157?+
It is the most common pairing in the injury-repair space, and the rationale is that they act through partly different mechanisms — BPC-157 primarily on local angiogenesis and fibroblast behaviour, TB-500 systemically on actin dynamics and cell migration. No study has tested the combination, so the synergy is a reasonable hypothesis rather than an established fact.
Do I need a maintenance phase?+
Only if the loading phase clearly helped and symptoms return after stopping. Most people run 4-6 weeks of twice-weekly loading and then either stop entirely or drop to 2-2.5 mg every one to two weeks.
References
- 1.A first-in-human, randomized, double-blind, single- and multiple-dose, phase I study of recombinant human thymosin β4 in healthy Chinese volunteers — Journal of Cellular and Molecular Medicine (2021) PMID 34346165
- 2.Animal studies with thymosin beta, a multifunctional tissue repair and regeneration peptide — Annals of the New York Academy of Sciences (2010) PMID 20536453
- 3.Advances in the basic and clinical applications of thymosin β4 — Expert Opinion on Biological Therapy (2015) PMID 26096726
More healing & recovery
BPC-157
Gastric-juice-derived pentadecapeptide studied for tendon, ligament and gut healing.
250 mcg · 1x daily (some split into 2x daily during an acute injury)
GHK-Cu
Copper-carrying tripeptide studied for collagen synthesis, wound repair and skin remodelling.
2 mg · 1x daily
KPV
Tripeptide tail of alpha-MSH used to damp gut and skin inflammation.
500 mcg · 1x daily