All seven vendors we compared in September list TB-500 for laboratory research, and Peptide Plugs documents it best: its product page gives the lot, a Freedom Diagnostics accession code you can check at the lab, purity and measured content. Alpha Pro Peptides, PSPeptides and Ascension Peptides also post TB-500 certificates with a named lab and a lot or batch number. None of the seven has independent Finnrick data for TB-500.
Notice: Research peptides are sold for in-vitro laboratory research only. They are not FDA-approved, not for human or animal consumption, and this page is not medical advice.
We rank documentation, not the product. A TB-500-specific COA with a named lab and lot number beats a generic "third-party tested" badge. TB-500 adds a second check: whether the certificate identifies the molecule you think you're buying (see below).
Regulatory status of TB-500
- FDA: TB-500 is not an approved drug. FDA's Category 2 compounding page (updated April 22, 2026) lists "Thymosin beta-4, fragment (LKKTETQ), also known as TB-500" among nominations "withdrawn by the nominators." HHS Secretary Robert F. Kennedy Jr.'s February 27, 2026 announcement named TB-500 among peptides expected to leave Category 2 (Pharmacy Times).
- July 2026 advisory vote: the Pharmacy Compounding Advisory Committee voted 8 yes, 6 no, 1 abstaining to recommend TB-500 for the 503A bulks list (McDermott Will & Schulte; NCPA). It's non-binding, and FDA would still need rulemaking. It concerns licensed pharmacies, not research-use sales.
- WADA: the 2026 Prohibited List bans "Thymosin-β4 and its derivatives e.g. TB-500" under S2.3 growth factors, at all times (2026 list text).
- DEA: not on DEA's controlled substances list dated August 27, 2026.
Background: are peptides legal? and FDA peptide regulation in 2026.
TB-500 by vendor
Single-vial prices as shown on September 26, 2026, including any displayed sale price. $/mg is price divided by labeled mg. Vendors appear in our editors' order, which isn't sorted by score.
| Vendor | Stocks it | Vial size(s) | Price | $/mg | TB-500 COA / lab | Review |
|---|
| American Peptides | Yes | 10 mg | $100 (list) | $10.00 | Lot TB10-0803; lab not shown | Review |
| NextGenPeps | Yes | 10 mg | $72 | $7.20 | BioRegen, Dec 31, 2025, 99.60%; no lot shown | Review |
| PSPeptides | Yes | 5, 10 mg | $44.99 / $79.99 | $9.00 / $8.00 | North American Diagnostics, batch PSP-06112026TB, June 11, 2026 | Review |
| Ascension Peptides | Yes | 5 mg | $54.00 | $10.80 | Kovera Labs, batch 31-05260628, June 2, 2026 | Review |
| Peptide Plugs | Yes | 10 mg | $50 | $5.00 | Freedom Diagnostics, lot 101610L-DK, accession code | Review |
| Swiss Chems | Yes | 2, 5, 10 mg | $23.96 / $35.16 / $42.36 | $11.98 / $7.03 / $4.24 | HPLC report Sept 4, 2026; lab not named on page | Review |
| Alpha Pro Peptides | Yes | 5, 10 mg | $34.99 / $44.99 | $7.00 / $4.50 | Freedom Diagnostics, lot AP-TB10-0426, May 18, 2026 | Review |
Notes on the table:
- American Peptides: the TB-500 page lists one 10 mg vial at $100; an automatic daily discount showed $75 when we checked. Its COA page has a lot-matched certificate, but the lab isn't named there.
- NextGenPeps: the product page showed $72; the category page showed a lower figure, so confirm at checkout. The only TB-500 entry in its COA library is from December 2025.
- PSPeptides: the June 2026 10 mg certificate reports 99.93% purity and 9.91 mg measured. Code CHECKED takes 10% off.
- Ascension Peptides: the 5 mg page lists Kovera Labs (June 2026) and MZ Biolabs (February 2026) batches (checked September 26, 2026). Code AFFILIATE50OFF applies to a first order.
- Peptide Plugs: the 10 mg page reports 99.35% purity and 12.65 mg measured, a 26.5% overfill against the label.
- Swiss Chems: sells "TB-500 (Thymosin Beta-4)" and, separately, a "TB-500 Fragment (17-23)." Its page lists HPLC, heavy metal, contamination and endotoxin reports for 5 mg. Finnrick has no TB-500 tests for it.
- Alpha Pro Peptides: the 10 mg certificate is from Freedom Diagnostics: 99.66% purity, 11.36 mg net content.
- Licensed Peptides (added to our list September 28, 2026; not in the table): it has no standalone TB-500 vial. It sells TB-500 only in a BPC-157/TB-500 blend ("Wolverine," 20mg) from $99.99 (shop, checked September 28, 2026). Review
What is TB-500?
Thymosin beta-4 is "a small ubiquitous protein containing 43 aa" and "the major actin-sequestering molecule in eukaryotic cells," according to a 2010 FASEB Journal paper. That paper identifies LKKTETQ as its central actin-binding domain (amino acids 17-23 plus one) and studies which short sequences carry its activity in lab models.
The name "TB-500" isn't used consistently. FDA identifies it as the LKKTETQ fragment. Some vendors describe their TB-500 as the full 43-amino-acid sequence, and Swiss Chems sells both. The two molecules differ greatly in mass, so check which one the certificate's mass spectrometry result matches.
How to check a TB-500 COA
- Confirm the molecule. The COA should name the sequence or give a mass that matches the product description.
- Match the lot or batch on the certificate to your vial label.
- Find the lab name on the PDF and use the lab's lookup where one exists.
- Compare measured content to the label. Large overfills or underfills both matter for lab calculations.
See how to read a peptide COA and the COA checklist. For concentration math after reconstitution, use the reconstitution calculator.
Independent test data
None of the seven vendors we compared had independent Finnrick results for TB-500 on September 26, 2026. Licensed Peptides, which we added on September 28, 2026, has no Finnrick profile. Finnrick has ten tests for Swiss Chems, but none cover TB-500, and the other six vendors we compared have no Finnrick tests at all. So every TB-500 certificate above was commissioned by the vendor, which chooses the sample it sends. That makes lot matching and lab-side verification the main checks available to you. More on how community testing works: what is Finnrick?
Vendor links
In our editors' order. Each review covers the vendor's policies, red flags and full testing record.
Comparing blends? See BPC-157 + TB-500 blend (Wolverine) vendors and GLOW and KLOW blends.
Bottom line
Peptide Plugs leads on TB-500 documentation, with Alpha Pro Peptides, PSPeptides and Ascension Peptides close behind. NextGenPeps names its lab but its only TB-500 certificate is from late 2025. American Peptides and Swiss Chems don't show the lab on the page. For the full vendor comparison, see best peptide vendors in the USA and third-party tested peptides. Related: best BPC-157 vendors.
Rank 1
