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TB-500: what it is, research and calculator

TB-500 explained in plain English: what it is, what the research shows, side effects, legal status and dosage, plus a calculator for syringe units. There is no validated human dose, and this page doesn't invent one. Also called TB500, Thymosin beta-4 fragment, Ac-LKKTETQ.

TB-500 is not approved for human use by the FDA or any other regulator. This page is educational; talk with a qualified healthcare professional before using any substance.

Calculate
Vial unit

= 5,000 mcg

mL
Dose unit
Syringe type
Syringe size

Units to draw

–units

Enter your dose.

Syringe, no result yetU-100, 1 mL syringe holding up to 100 units. Enter your dose.0102030405060708090100

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What is TB-500?

TB-500 is a synthetic peptide made from a short piece of thymosin beta-4, a protein the body makes naturally. It copies the seven amino acids thought to drive that protein’s activity (written Ac-LKKTETQ), so it is much smaller than the full protein.

It is sold as a powder in a sealed vial, most often 2 mg, 5 mg or 10 mg, and has to be mixed with bacteriostatic water before use. That mixing step is where the math above comes in.

What does the research on TB-500 show?

There are no published controlled trials of TB-500 in people. Most of the research behind it was done on the full thymosin beta-4 protein, in cells and animals, looking at wound healing, blood vessel growth and inflammation.

The full protein has been tested in people for some eye and skin conditions, but those results don’t automatically apply to the much smaller TB-500 fragment. Products sold online as “research chemicals” are not checked for purity or labeling, and TB-500 has been found in horse-racing doping cases.

TB-500 is not approved for human use by the FDA or by any other regulator. Its rules for pharmacy compounding in the US changed in 2026:

  • FDA concerns: the FDA has said compounded thymosin beta-4 fragment may carry a risk of immune reactions and impurities, and that it found no human exposure data for it.
  • April 2026: the nominations for the fragment were withdrawn, so it moved off the FDA’s list of compounding substances with safety concerns (Category 2). That is not an approval.
  • July 2026: an FDA advisory committee voted to recommend adding TB-500 to the list of substances pharmacies may compound. The vote is advisory only; the FDA still has to decide, and pharmacies can’t compound it under that list until it does.
  • Sport: the World Anti-Doping Agency bans TB-500 and thymosin beta-4 at all times, so athletes who are tested can’t use it.

Laws differ between countries and change over time. Check the rules where you live.

How do you reconstitute TB-500?

You mix the powder with bacteriostatic water, then use the calculator to turn your dose into syringe units. The step-by-step method is the same for any peptide vial: see how to reconstitute peptides, and choosing how much water to add for picking an amount of water.

This site gives no dose for TB-500. The dose you enter should come from a qualified healthcare professional.

TB-500 dosage

TB-500 has no published human trials, so there is no validated human dose. Doses quoted online come from sellers and forums, not studies.

There is no approved or validated human dose. This site does not repeat doses from forums, sellers or animal studies.

Medical disclaimer: this dosage information is for education only and comes from the source shown for each row. It is not medical advice and not a recommendation for you. Only a licensed prescriber who knows your health can decide whether TB-500 is right for you and at what dose. Don't start, change or stop a medicine based on this page, and don't use research peptides or unapproved drugs based on trial doses.

TB-500 concentration chart

The concentration of a TB-500 vial depends only on its size and the water you add. Each unit on a U-100 syringe holds one hundredth of a mL.

TB-500 concentration by vial size and water
Vial + waterConcentrationPer unit (U-100)
2 mg + 1 mL2,000 mcg/mL (2 mg/mL)20 mcg per unit (0.02 mg per unit)
2 mg + 2 mL1,000 mcg/mL (1 mg/mL)10 mcg per unit (0.01 mg per unit)
2 mg + 3 mL666.67 mcg/mL (0.66667 mg/mL)6.67 mcg per unit (0.00667 mg per unit)
5 mg + 1 mL5,000 mcg/mL (5 mg/mL)50 mcg per unit (0.05 mg per unit)
5 mg + 2 mL2,500 mcg/mL (2.5 mg/mL)25 mcg per unit (0.025 mg per unit)
5 mg + 3 mL1,666.67 mcg/mL (1.66667 mg/mL)16.67 mcg per unit (0.01667 mg per unit)
10 mg + 1 mL10,000 mcg/mL (10 mg/mL)100 mcg per unit (0.1 mg per unit)
10 mg + 2 mL5,000 mcg/mL (5 mg/mL)50 mcg per unit (0.05 mg per unit)
10 mg + 3 mL3,333.33 mcg/mL (3.33333 mg/mL)33.33 mcg per unit (0.03333 mg per unit)

Frequently asked questions

What is TB500?

TB500 is another way of writing TB-500, a lab-made fragment of the natural protein thymosin beta-4. It is a research peptide that is not approved for human use.

Is TB-500 the same as thymosin beta-4?

No. TB-500 is a short synthetic piece of thymosin beta-4, a natural protein in the body. Research on the full protein doesn't automatically apply to the fragment.

Does this calculator tell me what dose of TB-500 to use?

No. It only does the math for a dose you enter. TB-500 has no approved dose, and this site never suggests one; talk with a qualified healthcare professional.

Is TB-500 FDA approved?

No. TB-500 is not approved by the FDA, or by any other regulator, for use in people. In 2026 an FDA advisory committee recommended allowing it in compounding, but that vote is not binding.

Is TB-500 banned in sport?

Yes. The World Anti-Doping Agency prohibits TB-500 and other forms of thymosin beta-4 at all times under section S2.

Sources

  1. FDA, Certain Bulk Drug Substances for Use in Compounding that May Present Significant Safety Risks
  2. FDA, July 23-24, 2026 Meeting of the Pharmacy Compounding Advisory Committee
  3. World Anti-Doping Agency, The Prohibited List
  4. Esposito et al. (2012), Synthesis and characterization of the N-terminal acetylated 17-23 fragment of thymosin beta 4 identified in TB-500, Drug Testing and Analysis

Last updated .

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