TB-500
A fragment of Thymosin Beta-4. Drives cell migration and tissue repair, used for chronic soft-tissue stuff.
TB-500: A fragment of Thymosin Beta-4. Drives cell migration and tissue repair, used for chronic soft-tissue stuff. TB-500 is a fragment of a natural healing protein your body already makes.
TB-500 is a fragment of a natural healing protein your body already makes. It's used for chronic injuries that won't resolve on their own, old shoulder issues, lingering tendon pain. You usually pair it with BPC-157 for a stronger combined effect.
Recommended by FDA's advisory committee on July 23, 2026, against the recommendation of FDA's review staff. The vote is advisory, does not bind FDA, and no rulemaking has followed.
Not prescribed in conventional medicine.
Who it's for
- →Anyone with a chronic soft-tissue injury that won't resolve
- →Lifters running BPC-157 for synergy
- →Athletes in connective-tissue recovery phases
What to expect
- Week 1
Mild fatigue first few days from the loading phase.
- Week 4
Loading phase ends. Most users feel the underlying injury settling.
- Week 8
Maintenance phase. Cumulative effect on chronic tissue.
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How it works (mechanism)
Active fragment of Thymosin Beta-4 that binds and sequesters G-actin, accelerating cell migration to wound sites. Promotes endothelial migration, capillary formation, and tissue repair across multiple organs.
Dosing protocol
Stacks well with
Stack essentials
Side effects
When NOT to use
- ⚠Active malignancy
- ⚠Pregnancy / nursing (no data)
Common mistakes
- • Skipping the loading phase, then wondering why nothing happened
- • Stopping at 4 weeks instead of completing the full cycle
- • Storing reconstituted vials at room temp instead of refrigerated
What it actually is
TB-500 is a synthetic version of a short active fragment of thymosin beta-4, a protein your cells make that is involved in tissue repair and cell migration. The important distinction on this page: the large and genuinely interesting scientific literature is about thymosin beta-4, the full protein, and mostly in animals. TB-500 is the fragment sold to consumers, and it is not the same thing as the molecule most of those papers studied. It is not approved anywhere and is banned in sport.
Thymosin beta-4's main job is binding actin, the protein that forms the internal scaffolding cells use to move. By regulating actin assembly it helps cells migrate into damaged tissue, which is the first step of repair, and it promotes new blood vessel formation. The proposed logic for injuries is that giving more of the signal recruits more repair cells to the site. That mechanism is well described in cell and animal work; whether injecting a fragment of it into a human shoulder does anything is a separate question that has not been answered.
Forms, and which is which
Reconstituted by the buyer. Sold as research chemical, so identity and sterility are unverified.
Verdict: The only form, fully unregulated supply.
The molecule the published research is about. Rarely what is sold, and considerably more expensive to make.
Verdict: Closer to the science, and not what is in most vials.
The standard 'healing stack'. Combines two compounds with no human efficacy evidence, and makes anything you notice unattributable to either.
Verdict: Two unknowns, one syringe.
A peptide of this size is not absorbed intact from the gut, and topical delivery into a tendon is not established.
Verdict: Not plausible by the route claimed.
What it is claimed to do, graded
This is the reason essentially everyone takes it and there is no completed human trial demonstrating it. The supporting work is animal and cell-culture, using the full protein more often than the fragment.
There is a real and interesting animal literature on cardioprotection by thymosin beta-4. It has not translated into a human result.
Supported mechanistically and in animal models, and not demonstrated in any controlled human trial of TB-500.
Rodent data only.
Nobody has studied it. Promoting cell migration and blood vessel formation is also, in principle, what you do not want happening around an undetected tumour, and that concern is untested rather than excluded.
Grades describe how much human evidence exists for that specific claim, not whether it will work for you or whether it is safe.
Pros and cons
- • The underlying thymosin beta-4 biology is real and well characterised, not invented marketing
- • The underlying thymosin beta-4 biology is well described in cell and animal work
- • Widely available and inexpensive
- • Zero completed human efficacy trials for the injury use it is overwhelmingly taken for
- • No published human pharmacokinetic study exists for the TB-500 fragment, so the half-life figures circulating in dosing protocols are not established
- • FDA found no identifiable human exposure data by any route, which means 'well tolerated' is an absence of reports rather than a safety finding
- • The impressive paper count is thymosin beta-4 literature, not TB-500 literature — that gap is routinely used to oversell it
- • Banned by WADA, so tested athletes are out
- • Research-chemical supply with unverified identity, purity and sterility
- • Pro-angiogenic activity is a theoretical cancer concern nobody has excluded
When to stop
- • Any new lump, unexplained weight loss, or other cancer red flag
- • Injection-site reaction that spreads or becomes hot and painful
- • Pain that worsens rather than improves over a full cycle — that is a signal to get imaged, not to redose
- • You are entering a tested competition window
Interactions
Promoting cell migration and new blood vessels is the mechanism you least want near a tumour. Untested, and the theoretical concern is serious.
The usual pairing. Nothing is known about the combination in either direction, and it makes any effect or side effect impossible to attribute.
No interaction data exists in either direction. Listed because angiogenic activity and anticoagulation both act on vascular tissue, which is a reason to watch rather than a documented interaction.
Not an interaction. Loading protocols and graded rehab are what actually have evidence for tendon healing, and are the thing most users skip.
Steroids impair tendon healing. Nobody has studied whether the combination cancels out.
Is this for you?
- • People with a chronic soft-tissue problem who understand they are running an experiment, not a treatment
- • Anyone who is doing the loading protocol and the rehab, not the peptide instead of the rehab
- • You have active cancer or an undiagnosed lump
- • You are drug-tested in sport
- • You are pregnant or nursing
- • You are using it in place of physiotherapy or a diagnosis for an injury you have never had imaged
The one number
Sources for the claims above
- Multi-functional regenerative properties and clinical applications of thymosin beta-4
- Cardioprotection by thymosin beta-4
- Beta-thymosin biology overview
Drug & supplement interactions
- ⚠Limited documented drug interactions
- ⚠Theoretical caution with pro-angiogenic compounds in malignancy contexts
Community patterns
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TB-500 vs BPC-157, which is better?+
TB-500 vs GHK-Cu, which is better?+
Common questions about TB-500
Head-to-head with TB-500
Tracked alongside TB-500
Same goal, different aisle — each graded on its own evidence in the Pepdex catalog.
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