TB-500 side effects: what the studies found
Real adverse event rates, clinical trial discontinuation numbers, and documented safety warnings from peer-reviewed literature.
This page has not yet been reviewed by a credentialed medical professional. It is educational and is not medical advice.
Safety summary: TB-500
- Evidence level Animal studies only
- FDA approvedNo
- Trial discontinuationNo clinical trials have evaluated TB-500 to establish human discontinuation rates.
- WADA sport statusProhibited
In short: Human safety data for TB-500 is lacking. Theoretical concerns include effects on cell migration and blood vessel growth in people with cancer; Tβ4 expression is elevated in some tumours, though that does not show the peptide causes cancer. Quality and purity of grey-market products are the largest practical risk.
Not FDA-approved or authorized as a medication. Compounded research-grade preparations are unauthorized for human use.
Most common side effects
Reported symptoms in clinical trials and published pharmacology literature:
| Symptom | Reported rate | Clinical context & notes |
|---|---|---|
| No controlled human safety trials for TB-500 | Unknown | TB-500 is a synthetic fragment; published human trials exist only for full-length 43-amino-acid thymosin beta-4. |
| Transient lethargy or lightheadedness | Anecdotal | Self-reported by online users; not validated clinically. |
| Localized redness or swelling | Anecdotal | Common with unsterile subcutaneous injections. |
Serious risks and warnings
Potential adverse reactions and biological risks identified in research:
- Bacterial contamination & endotoxin shock: Unregulated online vials lack sterility certification and pharmaceutical batch testing.
- Theoretical tumor vascularization: Thymosin beta-4 promotes cell migration and angiogenesis, pathways involved in tumor metastasis in oncological research.
- Doping violation penalties: Prohibited in sport by WADA at all times; anti-doping laboratories test for TB-500 and its metabolites using mass spectrometry.
Contraindications
This compound should not be used in individuals with:
- Active cancer
- Athletes subject to WADA anti-doping regulations
- Unregulated non-sterile injection
Common questions about TB-500 safety
Is TB-500 the same as thymosin beta-4?
No. Thymosin beta-4 is a naturally occurring 43-amino-acid protein tested in clinical trials for eye injury and myocardial infarction. TB-500 sold online is typically a synthetic 4-to-7 amino acid fragment (Ac-SDKP or LKKTET) that has never been tested in human clinical trials.
Can TB-500 cause cancer?
There is no human evidence showing TB-500 causes cancer. However, oncology researchers note that full-length thymosin beta-4 is upregulated in certain metastatic cancers, prompting caution regarding unmonitored use.
Will TB-500 trigger a positive drug test?
Yes. WADA specifically bans thymosin beta-4 and its synthetic derivatives under Category S0. Accredited laboratories routinely test for its presence using LC-MS/MS.