TB-500
Also known as Thymosin Beta-4 fragment, TB4, Tβ4 fragment
Last reviewed · Awaiting clinical review
Main safety concerns
Human evidence is limited, and much of it is for the full thymosin beta-4 protein, not this fragment. Because it may promote blood vessel growth, avoid it with active or recent cancer.
- SeriousAvoid if: Active or recent cancer, or a strong family history
- SeriousAvoid if: Pregnancy or breastfeeding
- WarningUnknown long term risks, since there is no long term human safety data
Educational information, not medical advice. If you have symptoms that worry you, contact a clinician or emergency services.
What is known
A synthetic peptide based on the active part of thymosin beta-4, studied for tissue repair, flexibility, and recovery.
On this page
What it is and how it works
TB-500 is built from the active, actin binding region of thymosin beta-4, a natural protein involved in cell movement and repair. It is thought to help cells migrate to injured areas, support new blood vessel growth, and calm inflammation, which may speed healing of muscle, tendon, and other tissue. Like BPC-157, it clears the blood within a few hours, yet its tissue effects are thought to last longer. That is why it is dosed only once or twice a week rather than every day.[1]
Evidence by claim
Each claim is graded on its own. Tap a grade to see what it does and does not mean.
Supports wound healing and soft tissue repair.
Source type: Review
Repeated animal evidence for thymosin beta-4 and this fragment across many injury models. Direct human trials of the fragment are very limited.
The full parent protein has early human data for wound and heart repair.
Source type: Review, Other
This is full thymosin beta-4, not the TB-500 fragment. The two are often mixed up, so treat claims carefully.
Improves recovery, flexibility, and injury healing in people.
Popular in the community and in veterinary use, but not shown in human trials of the fragment.
No source cited for this claim.
Reported side effects
- WarningUnknown long term risks, since there is no long term human safety data[3]Animal studies have not shown a clear toxic dose, but long term human safety has not been studied.
- CautionInjection site reactions(common)[3]
- CautionTemporary tiredness, head fog, or headache(common)[3]Most often in the first week of loading, then it tends to fade.
- CautionMild flu like feelings during loading(uncommon)[3]
Interactions and combination risks
- InfoBPC-157
Very commonly stacked with BPC-157 for recovery, and combined with it in the GLOW and KLOW blends. No human data supports the combination.
TB-500 promotes cell migration and new blood vessel growth, which in theory could support tumor growth or spread.
Who should avoid it
- SeriousActive or recent cancer, or a strong family history
Its effects on cell migration and new blood vessel growth are a theoretical concern for feeding a tumor. Based on mechanism, not proven human cases, but clinicians advise avoiding it.
- SeriousPregnancy or breastfeeding
No safety data in pregnancy or breastfeeding.
Dosing
Placed after the evidence and risks on purpose. Nothing here is a recommendation for you.
| Route(s) | subcutaneous (abdomen), intramuscular near the injury |
|---|---|
| Typical range | Loading: about 2 to 2.5 mg twice a week for 4 to 6 weeks. Maintenance: about 2 mg every 1 to 2 weeks. |
| Frequency | Twice weekly during loading, then weekly or every other week |
| Half life used in the model | 2.5 hours |
| Cycle guidance | A 4 to 6 week loading phase, then a lower maintenance dose. |
| Notes | Human dosing comes from community practice, not trials. The circulating is short, only about 2 to 3 hours, so TB-500 does not build up in the blood. The infrequent, twice weekly schedule works because its tissue effects are thought to outlast its time in the blood, not because it accumulates. Each dose spikes and clears rather than stacking up. |
For the equipment itself, see syringes, needles, and the rest of the kit.
Reconstitution
| Vial sizes | 5 mg, 10 mg |
|---|---|
| Diluent | Bacteriostatic water for multi dose vials, or sterile water for single use |
| Concentration | Example: a 5 mg vial plus 1 mL of water gives 5 mg/mL, so a 2 mg dose is 0.4 mL, which is 40 units on a U-100 syringe. A 10 mg vial plus 2 mL gives the same 5 mg/mL. |
| Notes | TB-500 usually ships as 5 mg or 10 mg freeze dried vials. |
General reconstitution technique
Units and volume arithmetic
Converts between an amount and syringe units for the vial and diluent you enter. It starts empty and does not suggest an amount. Open the full calculator
Result
Fill in steps 1 to 3 to see the arithmetic. Nothing here is a suggested amount.
Settings live in the address bar, so a pasted link reopens this calculator as you left it.
Educational arithmetic only. It does not choose an amount for you and is not medical or dosing advice. Verify every calculation independently.
Storage and stability
Dry powder (lyophilized)
| Temperature | Freeze for long term storage, or 2 to 8 short term |
|---|---|
| Shelf life | Many months when frozen |
| Notes | Keep dry and out of light until you mix it. |
After mixing
| Temperature | 2 to 8 (refrigerated) |
|---|---|
| Shelf life | About 2 to 4 weeks |
| Notes | Do not freeze after mixing. Discard if cloudy or discolored. |
COA and purity notes
| Common adulterants | underdosed or mislabeled vials, TB-500 sold as a blend, such as with BPC-157, without clear amounts, confusion between the TB-500 fragment and full thymosin beta-4 |
|---|---|
| Mislabeling | Products vary in what they contain, and a label may not make clear whether it is the TB-500 fragment or the full thymosin beta-4 protein. A recent third party COA helps. |
| Notes | Sold as unregulated research material. TB-500 is also banned in most competitive sports. |
Sources
[1]The regenerative peptide thymosin beta 4 accelerates the rate of dermal healing in preclinical animal models and in patients
Annals of the New York Academy of Sciences 2012 (opens source in a new tab)· Review[2]TB-500 (Thymosin Beta 4 17-23 Fragment) trial registration
ClinicalTrials.gov 2026 (opens source in a new tab)· Other[3]World Anti-Doping Code International Standard: Prohibited List 2026
World Anti-Doping Agency (WADA) 2026 (opens source in a new tab)· Regulatory record[4]FDA Briefing Document, Pharmacy Compounding Advisory Committee, July 23 to 24, 2026: TB-500 Related Bulk Drug Substances
U.S. Food & Drug Administration 2026 (opens source in a new tab)· Regulatory record
Last reviewed 7 July 2026 · editorial status: reviewed