Peptide guide

TB-500

A synthetic thymosin beta-4 fragment studied for soft-tissue repair, flexibility, and recovery.

TB-500 is a lab-made peptide sold for soft-tissue recovery, marketed as a fragment of a natural healing protein called thymosin beta-4. The evidence behind it is almost entirely from animals and cell cultures, it isn’t FDA-approved, and one 2024 study found the fragment itself was inactive in a wound-healing test while a breakdown product was the active piece. People still run it, often stacked with BPC-157. The useful questions are how to handle it correctly and how to tell a real source from a scam.

By the Zapify Research team

Reviewed against 10 clinical & research sources · Updated June 2026 · Educational use only

Type: 7-aa peptideTβ4 fragment
Route: Subcutaneous
Typical dose: ~4–5 mg/wk loadsplit into 2 shots
Cycle: Load + maintainweeks, not forever
Storage: Mixed: 2–4 wksSealed: months
Status: Not FDA-approved

What is TB-500?

A seven-amino-acid acetyl-capped fragment (Ac-LKKTETQ) of thymosin beta-4 — not the same molecule as the full protein, and not FDA-approved for anything.

TB-500 is a synthetic peptide, a short chain of amino acids, the same building blocks that make up every protein in your body. The version people buy is seven amino acids long, with the sequence Ac-LKKTETQ. The molecule is small, and there’s nothing exotic behind the name.

It’s built from a piece of a natural protein called thymosin beta-4, often written Tβ4. That full protein is 43 amino acids long and shows up all over the body, where it helps cells move and helps tissue repair itself. TB-500 copies one active stretch of it, residues 17 through 23, the part tied to thymosin beta-4’s actin-binding activity. The acetyl cap at the front is a small chemical change that makes the fragment more stable.

That distinction matters more here than with most peptides. The natural full-length protein and the seven-amino-acid fragment aren’t the same molecule, and they don’t carry the same evidence. Most of the strongest research used full thymosin beta-4. What’s sold as TB-500 is the shorter fragment.

TB-500 isn’t FDA-approved for anything. There are no completed human efficacy trials for the injectable fragment, and the research that exists is overwhelmingly animal and cell-culture work. Treat it as an experimental research compound, not a proven medicine.

What is it studied for?

Read it as "studied for in rats and dishes," and note a 2024 test where the fragment itself didn't speed healing — its breakdown product did.

Almost all of this work was done in animals and in cell cultures, not people. The full thymosin beta-4 protein has reached human trials in cardiac and eye-injury programs, but the marketed TB-500 fragment has no completed human efficacy trials of its own. So “studied for” mostly means “studied for in rats and in dishes,” and that sits under every claim below.

Evidence behind the fragment

ManyAnimal & lab studies

NoneHuman trials of the fragment

The research has clustered in a few areas. Cell migration is the headline: by managing the supply of actin inside a cell, thymosin beta-4 helps cells move toward a wound and rebuild it. Around that, the research points to new blood-vessel growth feeding an injured area, lower inflammation, and faster closing of soft-tissue and skin wounds. The recovery and flexibility claims people repeat online trace back to this animal and lab work.

There’s an inconvenient finding worth knowing. A 2024 study measured TB-500 and its breakdown products in a wound-healing test. The marketed fragment, Ac-LKKTETQ, didn’t meaningfully speed healing. A smaller piece it breaks down into, Ac-LKKTE, did. The authors raised the possibility that the healing people pin on TB-500 comes from what the body turns it into, not the fragment you inject. One in-vitro study isn’t the last word, but it’s a real crack in the story sellers tell.

So the mechanism is partly settled and partly not. The actin-binding behavior of the parent protein is well characterized in the lab. Whether the short injected fragment reliably reproduces that in a living body, and through which active form, is still open.

Why people use it

People reach for it for lingering soft-tissue injuries and whole-body recovery, often stacked with BPC-157, but no human trial shows the fragment delivers.

Most people who try TB-500 land in one of a few situations. These are the reasons they reach for it, not evidence that it delivers:

A soft-tissue injury that won’t settle: a strained muscle, a cranky tendon or ligament, the kind of thing that lingers past rest and rehab.
Wanting broad, whole-body recovery rather than one specific joint, which is why people often pair it with BPC-157 and treat the stack as a recovery protocol.
Chasing flexibility and range of motion, a claim that comes straight from the cell-migration and connective-tissue research.
The grind of hard, repeated training, and wanting to keep training through it.

No human trial has shown the TB-500 fragment will do any of this, and a 2024 test suggests the fragment itself may not even be the active piece. What’s there is a coherent mechanism from the parent protein, a consistent signal in animal wound-healing work, and a mild reported side-effect profile. It’s worth being curious about. It isn’t enough to rely on, and it won’t replace the basics that actually have evidence: rest, rehab, sleep, and loading the tissue properly.

How to reconstitute TB-500

Mix with bacteriostatic water down the glass wall, never shaking; a 10 mg vial in 2 mL gives 5 mg/mL, so 50 units is 2.5 mg.

Your vial arrives as a small puck of dry powder. Before you can use it, you mix it into a liquid. That step is called reconstitution, and it’s the same process used for BPC-157 and most research peptides.

Step 1Start with powderWipe the rubber stopper with an alcohol swab.

Step 2Add bac. waterRun it slowly down the inside wall — never shake.

Step 3Draw your doseThe calculator gives the exact units to draw to.

Wipe the rubber stopper with an alcohol swab first, every time.
Use bacteriostatic water, not plain sterile water and not saline. The trace of benzyl alcohol in it holds back bacteria, which matters because you’ll be drawing from the same vial for weeks.
Add the water slowly, running it down the inside glass wall. Don’t blast it straight onto the powder.
Don’t shake it. Swirl gently and let it dissolve on its own. Shaking foams the solution and can damage the peptide.

A common setup is a 10 mg vial mixed with 2 mL of bacteriostatic water, which gives 5 mg/mL. On a U-100 insulin syringe, 50 units is then 2.5 mg. The water doesn’t change how much peptide is in the vial; it only sets the concentration, which decides how many units you draw. More water means a more dilute mix and a bigger draw for the same dose. You can’t ruin it with too much or too little, you only change the draw math, and that’s exactly what the calculator handles.

Calculate your exact TB-500 reconstitution →

Dose & units

No dose is FDA-approved; reported protocols load at roughly 4–5 mg per week for 4–6 weeks, then drop to about 2–2.5 mg weekly.

There is no FDA-approved dose for TB-500. Everything below is a range that clinics and write-ups report, not a medical standard. TB-500 is dosed in milligrams per week rather than micrograms per day like BPC-157, so the two don’t map onto each other. Decide what goes into your body with a licensed provider, not with this page.

Loading phase

Reported protocols usually start with a loading phase of roughly 4–5 mg per week, commonly split into two injections of about 2–2.5 mg spaced a few days apart, for the first 4–6 weeks.

Maintenance

After loading, most write-ups drop to a maintenance dose of about 2–2.5 mg once a week.

Cycling

A typical full cycle runs around 8–12 weeks counting both phases, then several weeks off before repeating. The exact split varies source to source, which itself tells you how soft these numbers are. Starting nearer the low end lets you notice any reaction before you’ve committed to more.

Load4–6 weeks

Maintain4–6 weeks

Offweeks

For the exact mark to draw to on your insulin syringe, don’t eyeball it. The calculator turns your vial size, water, and dose into the precise number of units.

Get your exact units →

Storage

Dry powder keeps for months at room temperature; once mixed, refrigerate at 2–8 °C and use within about 2–4 weeks before contamination becomes the limit.

Sealed & drySealed dry powder stays stable for months at room temperature and tolerates shipping heat before you mix it.

ReconstitutedRefrigerate at 2–8 °C in the main compartment and use within about 2–4 weeks; don't freeze, keep out of light, toss if cloudy.

You’ll see longer windows quoted for peptide vials. Those figures are beyond-use dates for a sealed, unmixed vial that a compounding pharmacy has stability-tested, and they stop applying the moment you add water. A mixed vial runs on the shorter clock instead, because that’s how long the preservative in bacteriostatic water reliably keeps the solution clean once you’re drawing from it.

That limit is about contamination, not potency — the peptide itself often stays good well beyond it. Reconstitute with plain sterile water instead of bacteriostatic and you drop to a day or two, since there’s no preservative holding bacteria back.

Don’t freeze a reconstituted vial, keep it out of direct light, write the mix date on the label, and throw it out if the solution ever turns cloudy or discolored, whatever the date says.

Side effects & safety

Reported effects are mild (injection-site irritation, brief fatigue), but it's WADA-banned since 2011 in and out of competition, and cancer history warrants caution.

The reported side effects are generally mild. That picture comes from animal studies and scattered user reports, not large human safety trials, so hold it loosely.

Most common: mild, short-lived redness, irritation, or discomfort at the injection site.
Less often: brief fatigue, a head-pressure or light-headed feeling in the first few days of a cycle, or temporary flushing.

Talk to a doctor before you start if you have a history of cancer. The same new-blood-vessel and cell-migration effects that might help healing could, in theory, also support tissue you don’t want growing. That’s unproven, but worth taking seriously. The same goes if you’re pregnant, breastfeeding, or managing a serious health condition.

If you compete, this one is stricter than BPC-157. TB-500, as thymosin beta-4 and its fragments, has been on the WADA Prohibited List since 2011, banned both in and out of competition rather than only on competition day. The U.S. Department of Defense applies the same prohibited categories to service members, and athletes have drawn multi-year bans. A positive test is a doping violation.

And the biggest risk here isn’t really the molecule. It’s whether what’s in the vial is actually TB-500, at the strength on the label. That comes down to where you buy it.

How to vet a source

In an unregulated market where vials come back underdosed or mislabeled, demand a batch-specific third-party COA whose lot number matches your vial.

This is an unregulated market, and a real share of independently tested vials come back underdosed, impure, or not even the compound on the label. With a small fragment like this one, a wrong or incomplete sequence is an easy way to get shorted, and you can’t see it in the powder. Where you buy matters more than almost anything else here. The one document that separates a real seller from a gamble is a certificate of analysis: a third-party lab’s report on what’s actually in the vial.

A real COA shows

An identity test (usually mass spectrometry) confirming the peptide is what the label says.
A purity figure from HPLC, typically 98% or higher.
A lot or batch number that matches the number printed on your vial.
A named, independent accredited lab and a recent test date.

Walk away if

There’s no COA, or it’s a generic image with no lot number.
The “certificate” comes from the seller instead of a third-party lab.
The lot number doesn’t match your vial, or there isn’t one at all.
It’s a flat image you can’t trace back to the lab that issued it.

That’s the standard worth holding any seller to, ours included. Ask for the batch-specific COA before you buy, match the lot number to your vial, and don’t accept a screenshot in place of a traceable report.

See the Zapify compound catalog →

Common questions about TB-500

Is TB-500 approved or proven to work in people?

No. It isn’t FDA-approved for any use, and the injectable fragment has no completed human efficacy trials. Almost all the evidence is animal and cell-culture work. The full-length thymosin beta-4 protein has been tested in people for heart and eye injuries, but that’s a different, larger molecule than the TB-500 fragment you’d buy.

TB-500 or BPC-157 — what’s the difference?

They’re different peptides often used for the same goal, soft-tissue recovery, and they’re frequently stacked. BPC-157 has more of its animal research in tendon, ligament, and gut tissue and is dosed in micrograms per day. TB-500, a thymosin beta-4 fragment, leans toward cell migration and flexibility across muscle and connective tissue and is dosed in milligrams per week. Neither is FDA-approved, and the same sourcing rules apply to both. One difference that matters for athletes: TB-500’s WADA ban covers both in and out of competition.

Is TB-500 actually thymosin beta-4?

Not the whole thing. Thymosin beta-4 is a natural 43-amino-acid protein. TB-500 is a synthetic 7-amino-acid fragment, Ac-LKKTETQ, copying the actin-binding region of that protein. They’re related but not interchangeable, and most of the strongest research used the full protein, not the fragment.

Why is TB-500 dosed in milligrams when BPC-157 is in micrograms?

It’s a different potency and a different reporting convention. BPC-157 reports cluster around 250–500 micrograms a day. TB-500 reports cluster around a few milligrams a week, split into two shots during loading. A milligram is a thousand micrograms, so the numbers look very different even though both doses are small. Don’t carry one peptide’s dose over to the other.

Why bacteriostatic water and not saline or sterile water?

Because you’ll be drawing from the same vial across weeks. Bacteriostatic water carries a trace of benzyl alcohol that holds back bacteria between draws; plain sterile water and saline have no preservative. On a multi-dose peptide vial, the professional sources all point the same way: bacteriostatic.

References

This page is for research and educational purposes only. It is not medical advice or a recommendation to use any compound. The dose ranges shown are reported by clinics and research literature, not validated medical standards, and TB-500 is not FDA-approved. Talk to a licensed medical provider about anything you put in your body.