Any new or unusual symptom after dosing. Because this compound has little or no human safety data, there is no established list of 'expected' effects to reassure you against — treat anything abnormal as a signal.
Stop at the first clearly abnormal reaction and reassess. Keep the vial and lot number in case you need to describe what you actually took.
Any severe or fast-worsening symptom — difficulty breathing, chest pain, fainting, severe pain — is a 911 call regardless of the compound.
Allergic reaction: hives, swelling of the lips, tongue or throat, wheezing or dizziness can escalate to anaphylaxis within minutes — call 911 immediately. Site infection: spreading redness, heat, swelling, pus or fever is not wait-and-see; an abscess or cellulitis can need drainage or IV antibiotics. Unverified product: grey-market vials are frequently mislabelled or contaminated, so a reaction may be to endotoxin or the wrong contents, not the named compound.
Thymosin Beta-4 is a 43-amino-acid actin-sequestering protein present in most cells. TB-500 is a synthetic fragment retaining the LKKTETQ actin-binding motif. By regulating G-actin availability it influences cell migration — the proposed basis for effects on angiogenesis, keratinocyte migration, and wound repair. Note that TB-500 and full-length Thymosin Beta-4 are frequently conflated in marketing; they are not the same molecule and the research literature largely concerns the full-length protein.
Full-length Thymosin Beta-4 reached clinical trials for dry eye and dermal wounds and did not reach approval. Preclinical models report cardiac, corneal, and dermal repair effects. Human evidence for the TB-500 fragment specifically is essentially absent.
Not FDA-approved. Was subject to FDA 503A bulk substance review; nomination withdrawn April 2026 without Category 1 placement. Prohibited in sport (WADA S0).
No meaningful long-term human safety data. Shares the pro-angiogenesis theoretical concern raised for BPC-157.
No human trial has ever established a dose for this compound. Any figure circulating online is extrapolated from animal studies or copied between vendors — it was not validated in people. That absence is the single most important dosing fact on this page. Circulating figures are extrapolated from animal studies of the full-length protein, not this fragment.
Reported from clinical trials or FDA labelling as a matter of record. It is not a recommendation, and for unapproved compounds no dose has been shown safe or effective in humans.
Above is what was administered in trials or on FDA labels, reported as fact. We do not convert it into a personal protocol, calculate a dose for your body weight, or tell you what to inject or how to reconstitute it — that decision belongs with a licensed physician. See our editorial policy.
Regulatory status changes. This page reflects our reading of public sources as of July 2026 and should be independently verified before it is relied upon.