BPC-157 and TB-500 are compared constantly and studied together almost never. Both are sold for the same imagined job — tissue repair — so the question "which one" is natural. The record behind the answer is thin in a specific way: each compound has a pile of animal work and no randomised human trial, and exactly one published experiment has put them side by side. This page lays out that record, the amounts that circulate for each, and how those amounts read on a syringe. It recommends neither.
The single-compound figures are on the BPC-157 dosage page and the TB-500 dosage page. Using the two together is a different question, covered on the BPC-157 and TB-500 guide. When both come pre-mixed in one vial, the per-peptide water and unit arithmetic is on the Wolverine blend reconstitution page. Routes and sites for the second compound are covered separately in TB-500 injection sites and routes.
Two different kinds of molecule
| BPC-157 | TB-500 | |
|---|---|---|
| What it is | 15-residue synthetic peptide, first described from a gastric protein | Described by vendors as residues 17–23 of thymosin beta-4 (LKKTETQ); the full protein is 43 residues |
| Human injectable data | One retrospective chart review of knee injections, 17 patients, no dose stated (PMID 34324435) | Only for the full protein: 42–1,260 mg intravenously in healthy volunteers (PMID 20536472), not the fragment |
| PubMed, title or abstract (2026-10-01) | 226 records, 0 randomised trials | 33 records naming TB-500; 602 naming thymosin beta-4 |
| ClinicalTrials.gov (2026-10-01) | 4 records | 1 record naming TB-500; 18 for thymosin beta-4 |
| FDA compounding status | Category 2 from 2023-09-29, withdrawn nomination by 2026-04-22; advisory vote 8–6–1 in favour, 2026-07-23 | Same, listed as "Thymosin Beta-4, Fragment (LKKTETQ)" |
The TB-500 row carries a trap: most of the human data people cite for "TB-500" is for thymosin beta-4, a molecule six times longer. The fragment itself has no human dosing study.
The one head-to-head experiment
Twelve PubMed records name both compounds. Nine are 2026 reviews or overviews, one is a doping-analysis method, one is the 2021 BPC-157 knee chart review — and one is an experiment. Biçer and colleagues (Joint Diseases and Related Surgery, July 2026, PMID 42542926) cut and repaired the Achilles tendon in 32 male rats and randomised them into four groups of eight:
| Group | Amount | Tendon strength vs control | Histology (total scores) |
|---|---|---|---|
| BPC-157 | 10 µg/kg/day | Higher, not significant | Numerically better, not significant |
| TB-500 | 60 µg/kg/day | Higher, significant (p < 0.05) | Significantly better on both scores |
| Both | Same amounts combined | — | Significantly better on one score; no gain over either alone |
| Control | — | — | — |
The authors call it exploratory, and the limits are plain: eight animals per group, one injury model, four weeks, injection into the abdominal cavity rather than under the skin, and one amount of each compound. It is still the only controlled comparison anywhere in the record. Neither compound has a measured oral bioavailability either; the BPC-157 side of that gap is on the capsules-versus-injection page.
The rat amounts, scaled for scale
FDA's 2005 guidance on first-in-human starting doses converts a rat dose to a human-equivalent dose by dividing mg/kg by 6.2 (Table 1, body-surface-area method). Applied to the head-to-head study:
| Rat, per kg per day | Human-equivalent, per kg | 80 kg adult | |
|---|---|---|---|
| BPC-157 | 10 µg | 1.6 µg | about 130 µg |
| TB-500 | 60 µg | 9.7 µg | about 770 µg |
This is arithmetic, not a dose. The FDA method exists to estimate a cautious starting point for a first human trial, and the study it is applied to measured tendons, not people.
What circulates, per injection and per week
Vendor, clinic and forum pages read for this site on 2026-09-18 describe the two very differently:
| Per injection | Frequency | Per week | |
|---|---|---|---|
| BPC-157 | 250–500 µg | Once or twice daily | 1.75–7 mg |
| TB-500 | 2–2.5 mg | Twice weekly, then weekly or fortnightly | 4–5 mg (loading phase) |
Per injection the circulating TB-500 amount is four to ten times the BPC-157 amount; per week the ranges overlap. Neither set of figures traces to a label, a trial or a paper — they are what circulates, reported as such.
Both in syringe units
Units on a U-100 syringe = mg ÷ mg/mL × 100. Research vials of both are commonly labelled 5 mg and 10 mg.
| Amount | 2.5 mg/mL (5 mg + 2 mL) | 5 mg/mL (5 mg + 1 mL or 10 mg + 2 mL) | 10 mg/mL (10 mg + 1 mL) |
|---|---|---|---|
| BPC-157 250 µg | 10 units | 5 units | 2.5 units |
| BPC-157 500 µg | 20 units | 10 units | 5 units |
| TB-500 2 mg | 80 units | 40 units | 20 units |
| TB-500 2.5 mg | 100 units | 50 units | 25 units |
The two sit at opposite ends of the syringe. BPC-157's amounts are small enough that dilute mixing is what keeps them on readable marks; TB-500's are large enough that dilute mixing fills a whole 1 mL syringe. A 5 mg vial holds twenty 250 µg amounts of BPC-157 but only two 2.5 mg amounts of TB-500. Water volumes per vial are on BPC-157 reconstitution; the calculator's BPC-157 and TB-500 settings work any vial.
What is not established
No human trial has compared BPC-157 with TB-500, and neither has a randomised human trial of its own. The rat study used one amount of each, by a route people do not use, for four weeks. No human dose of the TB-500 fragment has been studied at all. Nothing on this page is a dose, a choice between the two or a plan. The compounds are covered in Medibact's BPC-157 guide and TB-500 guide.
Sources and dates
Opened 2026-10-01: PubMed searches and record summaries via NCBI E-utilities (counts above, and the 12 records naming both); abstracts PMID 42542926 (Biçer et al. 2026), 34324435 (Lee and Padgett 2021) and 20536472 (Ruff et al. 2010); ClinicalTrials.gov v2 searches for BPC-157, TB-500 and thymosin beta 4; FDA, Guidance for Industry: Estimating the Maximum Safe Starting Dose in Initial Clinical Trials for Therapeutics in Adult Healthy Volunteers (2005), Table 1. FDA's Category 2 listing, the 2026-07-23 advisory vote and the circulating amounts as recorded on this site's BPC-157 and TB-500 dosage pages (read 2026-09-18). Human-equivalent figures, weekly totals and units are arithmetic by this site. Corrections go to the contact page.