Peptide Guides
Important
TB-500 is not an approved medicine in any country. It holds no licence from the MHRA in the United Kingdom, the EMA in Europe, or the FDA in the United States. This guide describes the state of safety evidence. It is not medical advice, and nothing within it constitutes a recommendation to use TB-500. Products supplied through this site are intended for laboratory research use only.
Quick answer
- The compound sold as TB-500 has no published human safety studies at all.
- Small pharmaceutical trials of full-length thymosin beta-4, a related but different molecule, reported no significant adverse events, in small numbers of people, over short periods, under medical supervision.
- Human trials of full-length thymosin beta-4 provide some short-term safety data for that molecule. They cannot establish the safety of the TB-500 fragment, or answer questions about uncommon or long-term effects.
- Unknown is not the same as safe, and it is not the same as dangerous. It is unknown.
What Safety Data Exists for TB-500?
None has been published. The short lab-made section of thymosin beta-4 sold as TB-500 has never had a published human safety study. When the FDA reviewed the compound in July 2026, it stated that it had not identified human exposure data for products containing the TB-500 fragment.1 Claims about specific TB-500 side effects circulating online are not supported by any published human study of the compound itself; most are carried over from full-length thymosin beta-4 research, anecdote or theory. Understanding what TB-500 is, a short copied section of a much larger natural peptide, matters here more than anywhere.
What the thymosin beta-4 trials reported
Full-length thymosin beta-4 has been tested in people, in small pharmaceutical trials. A European dose-escalation trial in venous ulcer patients was designed around safety and tolerability monitoring, with weekly blood work.2 A 72-person dry eye trial of thymosin beta-4 eye drops reported that no adverse events were observed.3 A nine-person severe dry eye trial reported the drops were safe and well tolerated.4 A 2025 Cochrane review of the eye-drop trials found the risk of adverse events was similar to control groups, and rated the certainty of that evidence low.5
Those trials reported no clear short-term safety problems. But they tested full-length thymosin beta-4, not TB-500, and they were too small to catch anything that is not common.
What Cannot Be Concluded From Thymosin Beta-4 Research
Three things stop the thymosin beta-4 trials answering the safety question for TB-500. They tested a different molecule. They used pharmaceutical-grade material, mostly as eye drops or topical gels rather than by injection, under medical supervision. And they were small and short: a few dozen people for weeks cannot reveal uncommon effects, delayed effects, or anything about long-term exposure. The controlled human research that would establish a safety profile for the fragment as sold has never been done.
TB-500 and Cancer: What Is Actually Known?
This question comes up often, and for understandable reasons. Thymosin beta-4, a natural 43-amino-acid peptide, helps cells move and helps new blood vessels form. Those same processes are involved in how tumours grow and spread, which is why the peptide appears in cancer research, with findings pointing in both directions. That biology belongs to the full-length peptide. For the TB-500 fragment it creates a theoretical question, not demonstrated biology. Recent clinical reviews of unregulated peptides list pathological blood vessel growth and carcinogenesis among the theoretical risks of this compound class.6
The position is the same as for BPC-157 side effects: no study has shown that TB-500 causes cancer, and no study has been designed to detect whether it does. A theoretical risk with no data on either side stays a theoretical risk.
TB-500 Product Quality and Testing Risks
Research vials do not go through the pre-market authorisation and batch-release checks that licensed medicines do. Identity and purity therefore rest on batch-specific analytical testing. For TB-500 there is an added twist: different suppliers' products under the same name may contain the fragment or the full-length peptide. A batch-specific certificate of analysis reports what a tested sample actually contained. A label alone does not verify identity or purity.
Common questions
Is TB-500 safe?
Unknown. There are no published human safety studies of TB-500 as sold, and the small trials of its parent peptide cannot answer the question for it.
Does TB-500 cause cancer?
No study has shown that it does, and no study has been designed to find out. The theoretical concern exists because the compound's biology overlaps with processes tumours use, which is a reason for caution rather than a demonstrated harm.6
Are there long-term studies?
No. Nothing about long-term exposure to TB-500 has been published in humans in any form.
TB-500 Research Specification and Testing
Batch-tested TB-500 supplied through this site is freeze-dried (lyophilised) powder, purity-tested by HPLC with a dated certificate of analysis per batch. We publish what each batch contains and make no claims about what it does.
Supplied for laboratory research use only. Not for human consumption.
References
- US Food and Drug Administration. Pharmacy Compounding Advisory Committee Briefing Document: TB-500. July 2026. FDA briefing document
- Guarnera G, De Rosa A, Camerini R. Thymosin beta-4 and venous ulcers: clinical remarks on a European prospective, randomized study on safety, tolerability, and enhancement on healing. Ann N Y Acad Sci. 2007;1112:407-12. DOI
- Sosne G, Ousler GW. Thymosin beta 4 ophthalmic solution for dry eye: a randomized, placebo-controlled, Phase II clinical trial conducted using the controlled adverse environment (CAE) model. Clin Ophthalmol. 2015;9:877-84. DOI
- Sosne G, Dunn SP, Kim C. Thymosin β4 significantly improves signs and symptoms of severe dry eye in a phase 2 randomized trial. Cornea. 2015;34(5):491-6. DOI
- Kruoch Z, Choo AY, Kemp A, et al. Medical and surgical interventions for neurotrophic keratopathy. Cochrane Database Syst Rev. 2025;12:CD015723. DOI
- Moiz A, O'Keefe EL, O'Keefe JH. Dangers of injectable peptides and other unregulated "biohacking" drugs. Mo Med. 2026;123(4):337-343. PubMed