TB-500 Dosage and Side Effects: What Studies Actually Used — Not a Recommendation

"TB-500 side effects" and "TB-500 dosage" together get searched close to 1,900 times a month, and most of what answers either query treats TB-500 and thymosin beta-4 (Tβ4) as interchangeable — borrowing Tβ4's decades of research to answer a question about a molecule our evidence review already establishes is chemically distinct from it, with almost no dedicated literature of its own. That identity distinction matters just as much for dosage and safety as it does for efficacy, and this article holds onto it throughout: a number or finding sourced to full-length Tβ4 is not a TB-500 number or finding, and this article does not blur the two the way most marketing does.

What the animal dosing record actually shows — one study, one number

Unlike BPC-157, whose animal literature spans five studies and a six-order-of-magnitude dose range, TB-500's animal record narrows to a single dedicated study. A 2026 rat Achilles-tendon-repair trial — the only located animal study that tested TB-500 itself, rather than the full Tβ4 protein, as a named arm — dosed 8 rats with TB-500 at 60 micrograms per kilogram per day, injected intraperitoneally, daily, for 4 weeks, alongside separate control, BPC-157, and combined-treatment arms¹. That is the entire published TB-500-specific animal dosing record this review located: one number, from one study, in rats weighing a fraction of an adult human, by intraperitoneal injection — a route directly into the abdominal cavity, not the subcutaneous route most human use of TB-500 actually involves.

Worth restating from our evidence review because it bears directly on how much weight that single number can carry: a separate 2024 in vitro study, testing TB-500 and its breakdown products head-to-head in a fibroblast wound-healing assay, found that TB-500 itself did not show significant wound-healing activity — only a metabolite, Ac-LKKTE, did². That finding doesn't change the 2026 study's dose figure, but it's a direct reason to treat even that one animal result cautiously: the one paper that actually isolated TB-500 from its own breakdown products found TB-500 itself wasn't clearly the active ingredient at the tested dose.

Why there's no TB-500 dosing chart on this page

A chart converting 60 µg/kg/day in rats, dosed intraperitoneally, into a human subcutaneous schedule would require exactly the extrapolation our BPC-157 dosage article explains isn't supportable for a much larger, more-studied animal literature — a single rat study makes that extrapolation weaker still, not stronger. There is no completed human clinical trial of TB-500 of any kind — our evidence review documents a direct PubMed search returning zero human studies of the fragment itself — so there is also no human dose figure to report as an alternative. Our TB-500 reconstitution calculator will do the vial-to-syringe arithmetic on a number you already have, without validating that number against anything, because there is currently nothing published to validate it against.

What the safety record actually shows

No adverse finding is reported in the one dedicated animal study — but, as with every peptide this site reviews in this format, that's a narrower claim than it sounds. The 2026 Achilles-tendon study is an efficacy study, not a toxicology program, and it does not include a dedicated safety-endpoint section; its own results report biomechanical and histological outcomes, not an adverse-event tally¹. Absence of a reported problem in a study that wasn't looking for one carries less weight than a clean result from a dedicated safety study — a distinction our BPC-157 side-effects article draws the same way for its own knee-pain study.

There is no TB-500-specific human safety data of any kind. A direct PubMed search for TB-500 combined with toxicity, safety, and tolerability terms returns no dedicated human study — the same zero-result finding our evidence review already reports for TB-500 efficacy trials extends fully to the safety question. A 2026 sports-medicine review covering the broader category of unapproved research peptides TB-500 belongs to states the risk directly: "rigorous human safety data are scarce, and there is potential for serious harm to patients³" — a category-level statement, not a TB-500-specific finding, but one this review has no TB-500-specific human data to weigh against either way.

TB-500 is a banned substance in competitive sport, alongside full-length Tβ4. A 2026 orthopedic sports-medicine primer states plainly that "TB-4 and its derivative TB-500... remain banned substances in sports⁴" — worth knowing regardless of where FDA's compounding review lands, for any reader who is a tested athlete.

Do not borrow thymosin beta-4's human safety record. Our evidence review documents a real, decades-long human trial program for full-length Tβ4 — completed Phase 1 and Phase 2 studies in dry eye and venous stasis ulcers. That trial program never dosed TB-500, and this article does not treat its safety findings as applicable to the fragment sold under TB-500's name — the same identity discipline the evidence review applies to efficacy, extended here to safety.

The regulatory record is itself a safety-relevant signal. TB-500 sat in FDA's interim 503A Category 2 (significant safety risk) bulk-substances list from 2023 until its removal on April 15, 2026, via nominator withdrawal — a procedural change, not an FDA safety reversal. On July 23, 2026, FDA's Pharmacy Compounding Advisory Committee voted 8-6, with one abstention, to recommend TB-500 for the 503A Bulks List, reviewed for the use "Wound healing" — an advisory vote, not a rule, with formal rulemaking not yet started as of this review⁵.

Contamination and manufacturing-quality risk is a separate, real category no efficacy or dose study can speak to. As with every unapproved compounded peptide this site reviews, nothing above tells a reader what's actually in a specific vial from an unregulated seller — purity, peptide content, and sterility are questions no published TB-500 study answers.

The bottom line

TB-500's dosage and safety record is thinner than BPC-157's on every axis this article checked: one animal study instead of five, one dose figure instead of a range, and zero human trials of any kind — not thin human data, none. What exists is a single rat tendon study using 60 µg/kg/day intraperitoneally, a separate cell-culture study raising real doubt about whether TB-500 itself (rather than a metabolite) is the active component, and a regulatory record that treats TB-500 as an open, actively-reviewed safety question. None of that supports a dosing chart, and none of it substitutes for the safety data that thymosin beta-4 — a different, related molecule — actually has. For the full evidence picture, see our TB-500 evidence review; for the peptide TB-500 is most often stacked with, see our BPC-157 dosage and side-effects articles, and our MOTS-c dosage and side-effects review for the same regulatory review cycle applied to a third peptide.