TB-500

BPC-157’s usual partner. It travels through the body to injured tissue and acts through the cell’s own skeleton.

Evidence: ELab & animal what's this?
Grade E for the injected fragment. Most human data are for the full parent protein.
Also known as: Thymosin β4 fragment · Ac-LKKTETQ · Tβ4 fragment
Class: Synthetic heptapeptide, the actin-binding region of Thymosin Beta-4

The 30-second version

WhatThe short active piece of Thymosin β4, a 43-amino-acid repair protein found throughout the body.

Why people use itMuscle, tendon, ligament and post-surgical recovery, usually together with BPC-157.

The honest catchThe human trials studied the full protein for eyes and wounds, not this fragment for injuries.

What it is

Thymosin β4 (Tβ4) is a natural repair protein. Researchers traced much of its healing activity to a short region built around the motif LKKTETQ, and TB-500 is a synthetic copy of that fragment. The aim was the parent protein’s repair effects in a smaller, cheaper molecule. Whether the fragment does everything the full protein does, at the doses people inject, isn’t settled.

How it works

Binds actin. Holds G-actin, the building block of the cell skeleton, and controls how cells change shape and move.

Cells migrate. Stem and progenitor cells travel more readily to injured tissue.

New vessels. Promotes angiogenesis, bringing blood supply to the repair site.

Less scarring. Dampens inflammation and myofibroblasts, which favours organised tissue over fibrosis.

Systemic. Homes to injury through the bloodstream, so the injection site matters less.

BPC-157 works mainly through nitric-oxide and growth-factor pathways, and TB-500 works through actin and cell migration. Because they cover different parts of repair, they’re commonly combined, and both appear in the GLOW and KLOW blends.

What the research shows

In people. The full Tβ4 protein reached advanced trials as topical products for dry eye (RGN-259) and chronic wounds (RGN-137), and an intravenous safety study in healthy volunteers found it well tolerated³. Cardiac-repair trials after heart attack were mixed. There are no completed human efficacy trials of injected TB-500 for musculoskeletal recovery.

In animals. Strong and replicated across independent labs. Tβ4 sped wound healing, angiogenesis, and cardiac and muscle repair through a consistent actin-based mechanism^1,2.

The repair biology is real and well replicated. The fragment people inject has never been tested in a human trial.

Evidence at a glance

Use	Grade	Best evidence	Main gap	Read
Soft-tissue repair	ELab & animal	Faster healing and angiogenesis in animals^1,2	Fragment untested in humans	Strong preclinical
Eye and wound (parent Tβ4)	BHuman trials	Human trials, well tolerated³	Not the fragment	Useful context
Cardiac repair	ELab & animal	Strong in animals, mixed in humans	Did not translate cleanly	Cautionary
Injury recovery	DCommunity use	Community reports of benefit	No trial	Unproven

Dosing: what has been reported

Not a recommendation. These figures describe what was studied or what circulates in practice, kept separate so you can see how solid each one is. Speak with a qualified clinician before acting on any of it.

Setting	Figure	Route	Grade
Published human (fragment)	None	—	—
Community, loading	2–2.5 mg twice weekly for 4–6 weeks	SC or IM	D
Community, maintenance	2–2.5 mg weekly or every 2 weeks	SC or IM	D
Community, daily split	~700 mcg/day loading, ~350 mcg/day maintenance (same weekly total)	Subcutaneous	D

The daily split lets people combine it with BPC-157 in one injection. Because TB-500 lasts a long time, twice-weekly dosing works just as well. Daily dosing is a convenience, not a requirement.

Preparing & storing

Reconstitute with bacteriostatic water, swirl gently, refrigerate and keep away from light. It acts systemically, so the injection doesn’t need to be near the injury. Rotate sites.

Reported side effects

Brief tiredness or a head rush after injection
Injection-site redness or a lump
Occasional headache or mild nausea
Theoretical: its pro-angiogenic action could feed an existing cancer

Who should avoid it

Active, suspected or past cancer
Pregnancy and breastfeeding (Tβ4 has roles in embryonic development)
Blood thinners, clotting disorders or active heart disease (caution)
Tested athletes: WADA prohibited (S2), detectable

Regulatory status checked Oct 2026

Body	Status	Detail
FDA (US)	Not approved	Research compound; flagged in compounding review.
EMA (EU)	Not approved	No marketing authorisation.
CDSCO (India)	Not approved	No approval identified.
WADA	Prohibited	S2 peptide hormones and growth factors, at all times.

The NexGen read

Real repair biology, borrowed evidence

TB-500 has strong, replicated animal data and a sound mechanism, and the full parent protein has a clean human safety record. The injected fragment itself has never been tested in a human trial. Keep it away from any cancer history and out of tested sport.

References

Goldstein AL, Hannappel E, Kleinman HK. Thymosin β4: actin-sequestering protein moonlights to repair injured tissues. Trends Mol Med. 2005;11(9):421–429.
Bock-Marquette I, Saxena A, White MD, et al. Thymosin β4 activates integrin-linked kinase and promotes cardiac cell migration, survival and cardiac repair. Nature. 2004;432(7016):466–472.
Full-length Tβ4 human programme: IV safety studies; topical trials in dry eye (RGN-259) and chronic wounds (RGN-137). Context for the parent protein, not the fragment.