Where to buy Thymosin Alpha-1 (thymalfasin, Zadaxin) in the UK: the sellers with a verifiable COA
The newest verifiable Thymosin Alpha-1 certificate on any UK seller's website is on Peptology Labs (peptologylabs.uk), analysed 18 Sep 2026 (task #233906 on Janoshik's site); 3 verified sellers hold one covering Thymosin Alpha-1, listed newest first below. Of the 450 active UK sellers we audit, 38 (8%) publish their own verifiable Janoshik certificate of analysis, and this page lists which of them hold one covering Thymosin Alpha-1, newest certificate first. It is a record of paperwork, not a recommendation: The Peptide Watch sells nothing, takes no money from sellers and links to none of them. Thymosin alpha-1 is a 28-amino-acid thymic peptide isolated in 1977 and sold as thymalfasin (Zadaxin) in 37 countries, chiefly China, for hepatitis B and as a vaccine adjuvant. It has never been approved by the FDA, the EMA or the MHRA, and the largest recent trial, in sepsis, found no effect on mortality. Purity and identity cannot be judged by eye, so an independent certificate you can check is the only real proof of what is in the vial.
The one test that matters for Thymosin Alpha-1
Ignore the marketing. The question is simple: does the seller publish a verifiable Janoshik certificate that names the seller itself as the client? If it does, you can confirm an independent lab tested that batch. If it shows an in-house document, a borrowed certificate, or "COA on request", you cannot. Learn the two-minute check in how to verify a Janoshik COA.
Which UK sellers publish a verifiable COA
Of the 450 active UK research-peptide sellers we audit, only 38 (8%) publish their own verifiable Janoshik certificate. Any of them is where you can actually verify testing, for Thymosin Alpha-1 or any compound. A few: Lab77Peptides · Peptology Labs · Biovanta · Camo Chem · Biohackpeptides · Zenic Labs. See the full independently-tested list, or check a specific shop's certificate with the free COA Checker.
Verified UK vendors with a confirmed Thymosin Alpha-1 Janoshik certificate (3)
- Peptology Labs peptologylabs.uk · newest Thymosin Alpha-1 report 18 Sep 2026 · task #233906
- Biohackpeptides biohackpeptides.co.uk · newest Thymosin Alpha-1 report 21 May 2026 · task #162922
- Thoroughbredlabs thoroughbredlabs.co.uk · newest Thymosin Alpha-1 report 12 May 2026 · task #155575
Audit findings, not recommendations. Every entry is a report covering Thymosin Alpha-1 that we opened on Janoshik's own site and that names the seller itself as the client; the date is the analysis date printed on the report where we have read it, otherwise the date the laboratory received the sample. The table below is the same ledger in full, so the two always agree. Not exhaustive: a vendor whose Thymosin Alpha-1 report we have not yet read is not listed.
The 5 verifiable Thymosin Alpha-1 certificates we have read, newest first
Each row was opened on Janoshik's own site by a real page load and transcribed. The client column is the name the laboratory printed; a certificate counts as a seller's own only when that name is the seller. The report date is the analysis date printed on the report where we have read it, otherwise the date the laboratory received the sample. The verify link opens the laboratory, never the shop. Audit findings, not recommendations.
| Seller | Task | Client on the report | Report date | Result | Batch | |
|---|---|---|---|---|---|---|
| Peptology Labs | #233907 | Peptology Labs | 21 Sep 2026 | Endotoxin · 2.164 EU/vial | TA2865 | verify |
| Peptology Labs | #233906 | Peptology Labs | 18 Sep 2026 | Thymosin Alpha-1 · 5.36 mg · 99.885% | TA2865 | verify |
| Peptology Labs | #233908 | Peptology Labs | 18 Sep 2026 | As · not detected Cd · not detected Pb · not detected | TA2865 | verify |
| Biohackpeptides | #162922 | BiohackPeptides.co.uk | 21 May 2026 | Thymosin Alpha-1 · 4.51 mg · 99.904% | BHP26ETA5 | verify |
| Thoroughbredlabs | #155575 | Thoroughbred Labs | customerservice@thoroughbredlabs.co.uk | 12 May 2026 | Thymosin Alpha-1 · 5.58 mg · 99.202% | TBLTA103 | verify |
What the 5 Thymosin Alpha-1 certificates show
We have read 5 Janoshik reports covering Thymosin Alpha-1, published by 3 UK sellers. Each was opened on Janoshik's own website. All 5 name the seller itself as the client. All 5 are dated within the last six months. The newest is dated 21 Sep 2026 and the oldest 12 May 2026.
3 of the reports give a purity figure for Thymosin Alpha-1. The figures run from 99.202% to 99.904%, and all 3 are at 99% or above. 2 reports test for heavy metals or endotoxins instead. A purity figure describes the sample the laboratory received, not every vial from that batch.
Read directly from the newest reports: Peptology Labs: task #233906, analysed 18 Sep 2026, 5.36 mg recovered at 99.885%, client Peptology Labs; Biohackpeptides: task #162922, sample received 21 May 2026, 4.51 mg recovered at 99.904%, client BiohackPeptides.co.uk; Thoroughbredlabs: task #155575, sample received 12 May 2026, 5.58 mg recovered at 99.202%, client Thoroughbred Labs.
A certificate is a batch document. The lines that matter are the compound (it must say Thymosin Alpha-1, not only a batch code), the client (the shop, not its supplier) and the analysis date. A new batch is untested until a new report appears.
Questions people ask
Which UK sellers publish a verifiable Janoshik certificate naming Thymosin Alpha-1?
As of 4 October 2026, 3: Peptology Labs, Biohackpeptides, Thoroughbredlabs. Each has a report on Janoshik's own website that names the seller as the client and lists Thymosin Alpha-1. That is a statement about paperwork, not a recommendation; The Peptide Watch does not recommend anywhere to buy Thymosin Alpha-1.
How recent is the newest Thymosin Alpha-1 certificate from a UK seller?
The newest we have read is Janoshik task #233906, analysed 18 Sep 2026. It is published by Peptology Labs and names it as the client. A certificate covers one batch, so an old one says little about stock on sale today.
How do I check that a certificate for Thymosin Alpha-1 is genuine?
Four things: an independent laboratory is named; the client field names the seller you are buying from, not a supplier; the compound line says Thymosin Alpha-1; and the report's task number and key open the same report on the laboratory's own website (verify.janoshik.com). A branded PDF with no laboratory name and no verification code fails on the first check, however professional it looks. The free COA Checker on this site runs the checks for you.
Is Thymosin Alpha-1 a licensed medicine in the UK?
No UK marketing authorisation; the emc lists no thymalfasin product. Sold here as a research chemical. Licensed in 37 countries, chiefly China, for hepatitis B and as a vaccine adjuvant. Never approved by the FDA, the EMA or the MHRA. The Peptide Watch does not give legal or medical advice.
Why does The Peptide Watch not say where to buy Thymosin Alpha-1?
Because the site records paperwork, not recommendations. A verifiable certificate proves that a sample of one batch was tested. It does not prove the vial you receive matches it, and it says nothing about whether anyone should use Thymosin Alpha-1. Listing which sellers publish a certificate you can check, and which publish nothing, is as far as the evidence goes.
What the research shows for Thymosin Alpha-1, and what it does not
| Papers on PubMed | 887 |
|---|---|
| Indexed as rat or mouse studies | 269 |
| Indexed as clinical trials | 91 |
| Published since 2020 | 162 |
| Trials registered on ClinicalTrials.gov | 64 |
A licensed medicine in 37 countries, none of them the UK, the US or the EU. Thymosin alpha-1 was isolated from calf thymus by Allan Goldstein's group in 1977. SciClone's version, thymalfasin (Zadaxin), is approved in 37 countries according to the sponsor's own trial record, chiefly China, for hepatitis B and to boost vaccine response; it has never been approved by the FDA or the EMA and the electronic medicines compendium lists no UK product. PubMed indexes 887 papers, 91 clinical-trial reports and 5 phase 3 reports; ClinicalTrials.gov lists 64 registered trials, most run by Chinese hospitals.
The largest recent trial was negative. TESTS, published in the BMJ in 2025, randomised 1,106 adults with sepsis in China to thymosin alpha-1 or placebo: 28-day mortality was 23.4% against 24.1%, no clear effect. A 2026 Cochrane review of its use in chronic hepatitis B rated the evidence for a mortality benefit as very low certainty, from three small trials. Sellers describe it as an immune booster; the literature is a drug with a narrow, contested indication.
What a certificate can tell you. The two purity reports we read recovered 4.51 mg (99.904%) and 5.58 mg (99.202%) on 5 mg labels. Neither says anything about sterility or endotoxin, which for a 28-amino-acid injectable are the questions that matter.
Who owns Thymosin Alpha-1, and where it stands
| Originator | Allan Goldstein and colleagues, 1977 (isolated from thymosin fraction 5 of calf thymus). |
|---|---|
| Rights | SciClone Pharmaceuticals (Zadaxin); generic thymalfasin is made by several Chinese manufacturers. |
| Development status | Licensed elsewhere, not in the UK, US or EU. Licensed in 37 countries, chiefly China, for hepatitis B and as a vaccine adjuvant. Never approved by the FDA, the EMA or the MHRA. |
| Clinical trials | 64 registered on ClinicalTrials.gov (lead sponsors: Sun Yat-sen University, SciClone Pharmaceuticals, Beijing Friendship Hospital) |
| In the UK | No UK marketing authorisation; the emc lists no thymalfasin product. Sold here as a research chemical. |
Counts are from PubMed on 15 September 2026 using the queries recorded in our evidence file; "clinical trial" is PubMed's own publication-type index. This is a description of the published record, not medical advice and not an argument for or against use.
Sources (8)
- Thymosin alpha1: isolation and sequence analysis of an immunologically active thymic polypeptide. (Proc Natl Acad Sci U S A, 1977, PMID 265536)
- The efficacy and safety of thymosin α1 for sepsis (TESTS): multicentre, double blinded, randomised, placebo controlled, phase 3 trial. (BMJ, 2025, PMID 39814420)
- Thymosin-ɑ1 for people with chronic hepatitis B. (Cochrane Database Syst Rev, 2026, PMID 42713852)
- Immune enhancement in patients with predicted severe acute necrotising pancreatitis: a multicentre double-blind randomised controlled trial. (Intensive Care Med, 2022, PMID 35713670)
- The efficacy and safety of thymosin alpha-1 in Japanese patients with chronic hepatitis B; results from a randomized clinical trial. (J Viral Hepat, 2005, PMID 15850471)
- Thymosin α-1 in Cancer Therapy: Immunomodulatory Mechanisms, Clinical Applications, and Translational Perspectives. (Eur J Pharmacol, 2026, PMID 42641753)
- ClinicalTrials.gov NCT04487444, sponsor's description of Zadaxin approvals
- electronic medicines compendium, UK product search for thymalfasin
The Peptide Watch's position on Thymosin Alpha-1
No UK marketing authorisation; the emc lists no thymalfasin product. Sold here as a research chemical. The Peptide Watch reads the certificates UK sellers publish and does not recommend anywhere to buy Thymosin Alpha-1. Sellers on this page are listed by the date of their newest Thymosin Alpha-1 certificate and by nothing else. If you can verify a seller's testing, you can at least judge its evidence; if you cannot, you are taking the seller's word for what is in the vial. See how UK testing compares across every seller in the market statistics.
An honest note: a verifiable certificate proves a sample of a batch was tested, not that the specific vial you receive matches it, see what this can and can't tell you. The Peptide Watch sells no Thymosin Alpha-1 and links to no shop; this is research-use-only information, not medical or dosing advice.
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