There is no established human dose of TB-500, and the reason is straightforward: no published human study has administered TB-500. The trials people reach for when they quote a dose were run on thymosin beta-4, the full 43-amino-acid protein from which the marketed fragment is drawn, and they were run at scales and by routes that bear no relation to a weekly subcutaneous injection.
Setting the two side by side is the most useful thing this page can do. The evidence itself, rather than the arithmetic of dosing, is covered in what is known about TB-500.
The only dose-ranging study in people
A phase 1 study in 2010 put synthetic thymosin beta-4 through a conventional ascending-dose design, because the sponsor was pursuing it as a way of protecting heart muscle during a myocardial infarction [1].
Four cohorts of ten healthy volunteers each received a single intravenous dose of placebo or the peptide, at 42, 140, 420 or 1260 mg. After a safety review, each group then took the same dose daily for fourteen days.
Adverse events were infrequent and mild to moderate, with no dose-limiting toxicity and no serious events. The pharmacokinetics were dose-proportional, and the half-life lengthened as the dose rose.
That last detail matters more than it looks. A half-life that changes with dose means the body clears the peptide differently at different exposures, so a schedule worked out at one dose cannot simply be scaled to another.
| Study | Route | Dose given | What it found |
|---|---|---|---|
| Phase 1 in volunteers, 2010 | Intravenous | 42, 140, 420 or 1260 mg, single then daily for 14 days | Well tolerated; no dose-limiting toxicity |
| Dry eye phase 2, 2015 | Eye drops | 0.1% solution for 28 days | Both primary endpoints missed; some secondary endpoints improved |
| Venous ulcer study, 2007 | Topical, on the ulcer | Escalating doses, 84 days (protocol description) | Design paper; 21 patients enrolled at the lowest dose |
| Heart attack trial, 2025 | Recombinant protein, after angioplasty | First dose within 8 hours of the procedure | Overall infarct-area difference was not significant |
The topical doses are concentrations, not milligrams
The dry eye trial randomized 72 subjects with moderate to severe disease to either a 0.1% thymosin beta-4 ophthalmic solution or placebo for 28 days [2]. Neither primary endpoint separated from placebo.
Discomfort scores during the environmental challenge on day 28 were 27% lower than placebo, at P=0.0244, and two corneal staining measures improved. Those are secondary endpoints in a trial whose primary endpoints missed, which is a weaker claim than it is usually reported as.
The venous ulcer work is weaker still as a source of a dose. The paper most often cited for it is a description of a dose-escalation protocol, written while the study was still running, with 21 patients enrolled in the lowest group [3].
The animal doses are per kilogram, into the abdomen
The tendon study that circulates as support for TB-500 used 32 rats, each weighing about 330 g, after a standardized Achilles transection and repair [5].
The TB-500 group received 60 micrograms per kilogram per day, given intraperitoneally for four weeks. Maximum load to failure was higher than control at p<0.05, and the tissue scores were better, at p=0.016 for one scoring system and p=0.017 for the other.
A microgram-per-kilogram dose given into the abdominal cavity of a rat every day for a month is not a schedule anyone can translate into a human injection, because the route differs, the clearance differs and the healing timeline of a rat tendon differs. The same gap runs through BPC-157 dosage, which is the other half of that experiment.
Why no dose was ever set
A dose becomes established when a regulator reviews the trials behind it and a label is written. That has never happened here, and the compounding route is closed as well.
TB-500 appears on neither FDA list: not in the 503A bulk drug substances categories updated May 14, 2026, nor in the 503B categories updated March 21, 2025 [6].
FDA's compounding advisory committee voted 8-6, with one abstention, in July 2026 in favor of listing it[7]. That vote is a recommendation and is not binding, and pharmacies may not compound it until final rulemaking is in place.
Thymosin alpha-1, a different molecule with a similar name, sits in 503B Category 3 and is also outside any listed compounding route. The two are frequently confused, and they are covered separately in thymosin alpha 1.
Putting it together
The honest answer to a dosage question here is that the number does not exist. What exists is a phase 1 range for a different, larger molecule given by infusion, a 0.1% eye drop, and a rodent schedule in micrograms per kilogram.
Anyone weighing this should also read how unapproved peptides behave as products rather than as molecules, which is set out in whether peptides are safe and across the rest of the recovery hub.