What TB-500 is
Thymosin beta-4 (Tβ4) is a 43 amino acid protein found in nearly every cell in the body. Its main known job is binding actin, a building block of the cell's internal scaffolding, which affects how cells move during repair.
"TB-500" is a trade name, not a defined molecule. Vendors sell it as full-length synthetic Tβ4 or as a short fragment of it, and labels often don't say which. That matters, because research on one does not automatically apply to the other.
Regulatory status in 2026
TB-500 is not an approved drug and is not on the list of substances pharmacies may compound from. Its compounding status moved this year, but the end result has not changed for consumers.
FDA places TB-500 in Category 2 of its interim compounding list, flagging potential safety risks.
TB-500 is one of 12 peptides removed from Category 2 after nominations are withdrawn. Removal does not make it legal to compound.
FDA's advisory committee votes 8 to 6, with one abstention, to recommend adding TB-500 to the compounding list for wound healing. FDA staff had proposed not adding it.
FDA has not added TB-500 to the compounding list. Thymosin beta-4 and its derivatives remain prohibited in sport at all times under WADA class S2.
Regulatory status can change. Check the sources linked at the bottom of this page before relying on anything here.
Claims vs. what the research shows
Most TB-500 marketing borrows from research on full-length thymosin beta-4, much of it in animals. Very little of it was done on the fragments commonly sold as TB-500.
Speeds up recovery from muscle and tendon injuries.
Positive results in animal models with thymosin beta-4. No controlled human trials of TB-500 for injury recovery.
Animal or limited evidenceProven to heal wounds in people.
Full-length thymosin beta-4 was tested in small human trials for skin wounds and eye conditions. None led to an approved product.
Insufficient dataImproves flexibility and grows hair.
Based on animal observations and anecdotes. No human evidence.
Insufficient dataStorage and stability
Peptides break down with heat, light, moisture, and repeated freezing and thawing. Degraded product is one common reason two vials of the "same" peptide behave differently. These are general peptide handling practices. Your supplier's certificate of analysis or label takes priority.
Sealed powder (lyophilized)
- Refrigerate at 36 to 46°F (2 to 8°C) for routine storage.
- Freezer is generally used for long-term storage.
- Keep in its original sealed vial, away from light.
- Let a cold vial reach room temperature before opening to limit condensation.
After reconstitution
- Keep refrigerated. Do not freeze.
- Protect from light. Clear glass lets it through.
- Opened multi-dose bacteriostatic water is typically discarded 28 days after first puncture.
- Log the mix date so you know the vial's age at a glance.
Light exposure is easy to overlook in a fridge door that opens dozens of times a day. VIALTIGHT is building stackable cases that block light from every side. See vialtight.com for updates.
Reconstitution math
Concentration is just the amount of peptide divided by the volume of water added. On a U-100 insulin syringe, 100 units equals 1 mL, so each unit is 0.01 mL. Enter what is on your vial label and what you added to see the concentration.
This shows concentration only. It is not a dosing recommendation. VialTracker runs this math for every vial you log and keeps it with the vial's history.
Safety flags
Product quality is unverified. Gray-market vials have been found underdosed, mislabeled, or contaminated. A certificate of analysis from the seller is not the same as independent testing.
You may not know which molecule you have. Full-length Tβ4 and short fragments are sold under the same name. Check the certificate of analysis for the actual sequence and mass.
Growth-related questions are open. Thymosin beta-4 promotes cell migration and blood vessel growth in lab studies. Whether that matters for people with cancer or a cancer history has not been studied.
Tested athletes. Thymosin beta-4 and derivatives such as TB-500 are prohibited at all times under WADA class S2. Athletes have been sanctioned for it.
FAQ
Is TB-500 the same as thymosin beta-4?
Sometimes. The name is used for both full-length synthetic Tβ4 and shorter fragments. Only the certificate of analysis tells you which one a vial contains.
Did the FDA approve TB-500 in 2026?
No. An advisory committee voted to recommend adding it to the compounding list for wound healing. FDA has not acted on that recommendation, and TB-500 is not an approved drug.
Is TB-500 legal?
It cannot be legally marketed for human use. "Research use only" labeling does not change that.
Does VialTracker tell me what to take?
No. VialTracker organizes the information you enter and runs the math. It does not recommend doses, products, or protocols.