TB-500 / Thymosin Beta-4_Dosage, benefits & legal status
Also known as TB4, thymosin beta 4, TB-500 Frag 17-23, TB-500 fragment 17-23, Ac-LKKTETQ
A recovery peptide for healing muscle and tendon, often paired with BPC-157.
Common vial size is what vendors typically sell, not a recommendation. Enter your own vial in the calculator.
What is TB-500 / Thymosin Beta-4?
Plain language first. The technical label stays, but it never stands alone.Overview
People use it to help muscles, tendons and other tissue heal, and to move more freely. Most of the evidence is from animals. Most products sold are the short fragment rather than the full protein.
TB-500 is a synthetic fragment of thymosin beta-4, a natural protein involved in cell repair and movement.
What it's used for
A recovery peptide used to heal muscles, tendons, and other injuries faster and move more freely. It is often paired with BPC-157.
How does TB-500 / Thymosin Beta-4 work?
What it does in the body, and where.TB-500 is a fragment of thymosin beta-4, a protein your body already uses when tissue needs repairing. Its main job is helping cells move.
- 01It binds actin, the protein cells use to moveRepair depends on the right cells physically reaching the damaged area, and that movement runs on actin.
- 02Repair cells migrate to the injuryMore cells arriving means faster closure of a wound and, in animals, better-organised tissue afterward.
- 03The figures usually quoted are for a different moleculeMost published healing numbers are for full thymosin beta-4, not the TB-500 fragment sold for injection, and are from animals.
Where this compound is thought to act.
What else is it used for?
Each group carries its own evidence level.Approved means regulators have cleared it for that purpose. Investigational means it is in trials. Early research means it is being studied and is not established.
Wound healing
Research only- Animal studyIn rats, new skin growth over a wound increased 42% by day four and up to 61% by day seven against saline.
- Animal studyWound contraction was about 11% greater by day seven.
- Lab studyIn lab dishes it stimulated skin-cell migration two to three fold, still active at 10 picograms.
Heart and eye
Research only- Human trialIn a 2025 human trial of 96 heart attack patients, the injected full protein did not reduce overall damaged heart muscle; patients who received their first dose within eight hours showed less damage.
- Human trialLarge dry eye studies of the full protein did not meet their primary endpoints. A smaller symptom measure, gritty-eye feeling, improved.
- Human trialA small US corneal study found more healing with the full protein than placebo, but a larger European study failed outright.
- No dataAll human trials used the full 43 amino acid protein, not the seven amino acid TB-500 fragment.
Almost all the healing data, including the widely quoted 42% and 61% figures, comes from full-length Thymosin Beta-4, not the shorter TB-500 fragment sold online. They are different molecules and the results do not transfer directly. The fragment is seven amino acids; the full protein is forty-three.
Heart trial: Cardiovascular Research 121(17):2747-2758, PMID 41229390. Eye studies: RGN-259 (ARISE-3 and SEER-3). Dermal studies referenced in wound-healing source above.
The published record
52
Records indexed for TB-500 / Thymosin Beta-4
25 in humans, 15 of them original studies.
1 registered trials, 0 with posted results.
FDA: Left FDA category 2 in April 2026 when its nomination was withdrawn; not eligible for compounding, and FDA still lists an immune reaction risk.
Counted from Europe PMC indexing, not read by a person. Human means indexed under humans, which includes reviews and work on human cells. Original studies exclude reviews and lab work on human cells.Last updated 11 September 2026.
At a glance
Four things to know about TB-500 / Thymosin Beta-4
Evidence
Research only
Category
Muscle building
Common vial
10 mg
Half-life
Not established
How much, and do you cycle it?
The range, and whether you take breaks.2 up to 5 mg per week (start low, increase slowly), 1-2x per week. Commonly a loading period of 4 to 6 weeks, then less often, then stoppedCommunity practice
The loading-then-maintenance shape comes from community practice. No human study has tested a duration or a break.
How long does it stay in the body?
The half-life, and where the figure comes from.Not establishedNo figure
Figures from minutes to hours circulate. TB-500 as sold is a short fragment, and the published work is on the full-length protein, so the two are not interchangeable.
You can compare this against the whole library to see where it sits.
How do I dose and price it?
Enter your vial and your dose. Pick a mix. We show the draw and the cost.The vial holds a fixed amount of drug. Adding more water does not make more drug, it just spreads it thinner, so you draw a bigger number on the syringe for the same dose.
Choose your mix
Measuring the water1 mL = one full 100-unit syringe.
Your draw
40 / 100 unitsTB-500 / Thymosin Beta-4 starts at $21.57 across 77 vendors, typically $4.50 – $18.63 per mg.
186 listings, last read Sep 12, 2026. Shipping and card fees are not included.
How do you store it?
Before mixing, and after.Dry powder in the freezer or fridge. Once mixed, fridge, and use within about a month.
Unmixed lyophilized TB-500 / Thymosin Beta-4 keeps for a long time cold. Once you add water the clock starts: most reconstituted vials hold up for roughly 28 to 30 days at fridge temperature. Keep it out of light, and do not freeze it after mixing.
What are the side effects and cautions?
Known cautions and warnings for this compound.Who should avoid it
- Active cancer, as a precaution given the tissue-growth mechanism
- Pregnancy
- Banned in drug-tested sport
Stop and get help
- Signs of an allergic reaction
- New lumps or masses
Common effects
- Head rush or lightheadedness shortly after injecting
- Tiredness
- Injection-site reactions
What regulators say
Left FDA category 2 in April 2026 when its nomination was withdrawn; not eligible for compounding, and FDA still lists an immune reaction risk
In the FDA’s words: Nominated but withdrawn; previously category 2Listed as Thymosin beta-4, fragment (LKKTETQ), also known as TB-500. FDA has not identified any human exposure data
Checked 11 September 2026FDA: Certain Bulk Drug Substances for Use in Compounding that May Present Significant Safety Risks (category 2 and withdrawn nominations), current as of April 22, 2026
Where this page says nothing is established, that means nobody has studied it, not that a compound is safe.
Is TB-500 / Thymosin Beta-4 approved?
And where the numbers on this page come from.No. TB-500 / Thymosin Beta-4 is not approved for any use, anywhere. It is sold labelled for laboratory research only, and there is no legal route to buy it for human use.
- Approval statusResearch only
- RouteUnder the skin or into muscle
- CheckedAugust 2026
What has happened recently
Human trials of full-length thymosin beta-4 were run for wound and eye conditions and were generally well tolerated, but TB-500 as sold is a fragment, not the same molecule, and has no trial record of its own. On July 23, 2026, an FDA advisory committee voted 8 to 6 with one abstention to recommend adding TB-500 to the list of substances pharmacies may compound, for wound healing. The FDA's own scientific reviewers had advised against it. The vote is advice, not a decision, and compounding TB-500 is still not legal today.
Banned in drug-tested sport. Most research peptides are prohibited under WADA's S0 category, which covers any substance with no approval from any regulatory authority for human use. That means a compound can be banned without ever being named on the prohibited list. Check with your own anti-doping authority rather than assuming absence from the list means permitted.
You can compare this against the whole library, or read how to check a seller.
- DoseFrom research and community reports. No regulator has reviewed this dose.
- Vial sizeFrom what vendors typically list; not a recommendation.
- Sources
- Reviewed14 August 2026
What else is like TB-500 / Thymosin Beta-4?
Others in Muscle building, side by side.If you're weighing TB-500 / Thymosin Beta-4, it's worth reading Apitegromab, Trevogrumab, and GDF-8 (Myostatin) in the same class.
A recovery peptide for healing muscle and tendon, often paired with BPC-157.
- Dose
- 2 up to 5 mg per week (start low, increase slowly)
- How often
- 1-2x per week
An antibody tested to stop GLP-1 weight loss taking muscle along with fat.
- Dose
- 10 mg/kg per month (trial dose)
- How often
- Monthly
A myostatin antibody trialled with semaglutide, where the three-drug version got dangerous.
- Dose
- 200 or 400 mg (trial doses)
- How often
- In the trial schedule
The protein that limits muscle growth, which is the opposite of what most buyers want.
- Dose
- Research only
- How often
- Varies
Guides for this compound
- How to Reconstitute a Peptide
Mix peptide powder with bacteriostatic water, step by step.
- How to Read an Insulin Syringe
Read the units, convert to millilitres, and draw the exact dose.
- mcg vs mg: The Peptide Dosing Mistake to Avoid
Your vial says mg and your protocol says mcg. Here is the conversion and how to check it.
- BPC-157 and TB-500: What the Healing Pair Actually Is
They are different molecules, taken on different schedules, and one of them is not the molecule its research belongs to.
- How to Read a Peptide COA
What the purity number does and does not tell you, and how to spot an edited report.
Sources
- Malinda rat wound study, PubMed, 1999
- Phase 2 dermal wound trial, PubMed, 2012
- FDA, Pharmacy Compounding Advisory Committee meeting, July 23-24, 2026(2026)FDA meeting page listing the bulk drug substances reviewed and the uses considered.
Last reviewed 14 August 2026
Beyond these, 52 records are indexed. Browse the records