Loading phase (standard)
Timing and details
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Animal data onlyNot FDA approved
TB-500
Also known as: TB500 · TB 500 · Thymosin beta-4 fragment · Ac-LKKTETQ · TB-500 acetate
Updated 40 sources
In the analytical and anti-doping literature, TB-500 is Ac-LKKTETQ: a 7 amino acid fragment (residues 17 to 23, about 889 Da) of the 43 amino acid protein thymosin beta-4. What ships in a vial labelled TB-500 varies. People run it for soft-tissue recovery, usually with BPC-157, on a loading then maintenance schedule. Every human trial used the full protein, not the fragment.
Quick facts
- Half-life
- Not established in humans for the fragment. Full-length thymosin beta-4 by IV lasted longer at higher doses; one guide cites 0.5 to 2.1 hours.
- Routes
- Subcutaneous injection
- Intramuscular injection
- Forms
- Vial (powder)
- Reported dose ranges
- 1 to 5 mg (subcutaneous injection)
- 2 to 2.5 mg (intramuscular injection)
- 500 to 1,000 mcg (subcutaneous injection)
- 0.084 mg/kg (subcutaneous injection)
- Vial sizes
- 2 mg, 5 mg, 10 mg
- FDA status
- Not FDA approved
- WADA
- Prohibited
What people use TB-500 for
- Tendon, ligament and muscle injuries
- Recovery after surgery
- General recovery and inflammation
- Hair regrowth, based on mouse data
- Flexibility, from horse-racing lore
- Paired with BPC-157 in the Wolverine stack
How it is thought to work. The fragment is the actin-binding region of thymosin beta-4, the part tied to cell migration. It is seen as systemic, which is why people inject it anywhere rather than at the injury. In rats the metabolite Ac-LK dominates for the first 6 hours and Ac-LKK is still detectable at 72 hours. Human mechanism data for the fragment do not exist.
TB-500 dosing
19 protocols from studies, guides and community reports, grouped by goal. Tap a source badge to see where a number came from.
Loading phase2
Loading phase (intramuscular)
Timing and details
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Acute injury2
Acute injury
Acute injury, shorter
Other protocols: injected15
Maintenance phase
Loading by experience tier
Higher loading
Timing and details
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Conservative to high loading
Long-interval maintenance
Daily ladder (outlier)
Daily load then half (outlier)
Daily inside a BPC-157 stack (outlier)
Timing and details
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Low daily (outlier)
Every other day (outlier)
Microdose like BPC-157 (outlier)
Dog-scaled weekly total
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Forum high loading
Forum short loading
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Forum long run
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Doses shown are what sources report, labelled by origin. Not medical advice.
Full TB-500 dosage guideEvery titration step in syringe units, missed doses and how to mix.Vial strengths and syringe units
Every TB-500 vial size with the water volumes sources use. Units are what to draw on a U-100 insulin syringe, worked out exactly.
| Water | Strength | 2 mgdose, units | 2.5 mgdose, units | 5 mgdose, units |
|---|---|---|---|---|
| 2 mg vial | ||||
| 1 mLCompetitor guide | 2 mg/mL | 1001 mL | 1251.25 mL2 draws | 2502.5 mL3 draws |
| 5 mg vial | ||||
| 1 mLCompetitor guide | 5 mg/mL | 400.4 mL | 500.5 mL | 1001 mL |
| 2 mLCompetitor guide | 2.5 mg/mL | 800.8 mL | 1001 mL | 2002 mL2 draws |
| 10 mg vial | ||||
| 2 mLCompetitor guide | 5 mg/mL | 400.4 mL | 500.5 mL | 1001 mL |
| 3 mLCompetitor guide | 3.333 mg/mL | 600.6 mL | 750.75 mL | 1501.5 mL2 draws |
Units are on a U-100 insulin syringe (100 units = 1 mL). U-50 and U-30 barrels read the same units.Water volumes from
Doses shown are what sources report, labelled by origin. Not medical advice.
Calculate with this peptideYour vial, your water, your dose: TB-500 in syringe units, with the math shown.What people report
What TB-500 users write on Reddit, counted post by post. These are reports, not measured rates or advice.
Community-reportedFrom 900 Reddit posts and comments, last mined Oct 24, 2026r/Peptides, r/Biohackers, r/Peptidesource, r/PeptideDiscussion
Doses people report for TB-500
Injury recovery167 mentions
| Reported | Mentions |
|---|---|
| 500 mcg | 43 |
| 250 mcg | 19 |
| 1 mg | 18 |
| 2 mg | 15 |
| 5 mg | 10 |
Goal not stated59 mentions
| Reported | Mentions |
|---|---|
| 500 mcg | 18 |
| 250 mcg | 10 |
| 2.5 mg | 8 |
| 0.5 mg | 4 |
| 5 mg | 3 |
General use3 mentions
| Reported | Mentions |
|---|---|
| 1 mg | 2 |
Left out: 2 mentions given in syringe units, which mean different doses in different mixes; 3 mentions far outside every sourced protocol, most likely vial sizes or typos.
How often
| Reported | Mentions |
|---|---|
| Once a day | 88 |
| Twice a week | 36 |
| Twice a day | 20 |
| 5 days on, 2 off | 10 |
| Three times a week | 10 |
Most mentioned alongside
Side effects people mention
Fatigue10 mentions
Most common fix: lower the dose (2)
Sleep problems8 mentions
Most common fixes: stop usage (2), none mentioned (2)
Cystic acne6 mentions
Injection site redness4 mentions
Most common fix: change injection site (2)
Fast heart rate3 mentions
Anxiety3 mentions
Doses shown are what sources report, labelled by origin. Not medical advice.
If you miss a dose
Take it within a day, or skip it.
TB-500 side effects
What trials and labels report, kept apart from what users and guides report. Frequencies are worded as each source states them.
Reported by users and guides6
From community reports and dosing guides. Not measured rates.
Headache
The most-logged side effect in one app's user data (70 logs)
How people manage it
- Hydrate
Fatigue or lethargy
65 app logs; guides say it shows up 1 to 2 days after injections during loading
How people manage it
- Inject in the evening to sleep through it
Injection-site redness, sting or bruise
Called common by guides
How people manage it
- Rotate sites
Head rush or light-headedness
Rare
How people manage it
- Inject slowly
Flu-like feeling
Rare; 24 to 48 hours after the first loading dose
Nausea
Rare, mostly at 6 mg a week or more
How people manage it
- Eat a light meal first
Who should avoid it
Active or recent cancerCondition
Thymosin beta-4 is raised in several tumour types and tied to cancer cell migration in lab studies. No human data.
PregnancyCondition
Guides list it as a reason to avoid.
Tested sportCondition
Prohibited by WADA at all times under S2.3.
Storage
Powder (before mixing)
- Temperature
- -20 °C
Freezer at -20 C. One seller states up to 24 months at -20 C. A few weeks at room temperature is considered acceptable.
Mixed vial
- Temperature
- 2 to 8 °C
- Use within
- 28 days
Fridge at 2 to 8 C, dark, never frozen. Use-by advice runs from 7 days to 6 weeks: 21 days, 3 to 4 weeks and 28 to 30 days are most common. The 3 to 4 week window is the bacteriostatic water preservative, not TB-500 data. One guide gives 7 to 10 days for full-length thymosin beta-4.
Mixed with: Bacteriostatic water
Mixing. TB-500 doses are large by volume. One guide suggests picking the water so a dose lands between 20 and 60 units. Draws of 0.5 to 1 mL can be split across two sites.
Stacks people report
Combinations from guides and community posts, with the reason given.
The Wolverine stack: TB-500 2 to 2.5 mg twice weekly plus BPC-157 250 to 500 mcg a day near the injury, for 4 to 8 weeks. A rat Achilles study found the pair did no better than either alone, and one guide suggests running one at a time so you can tell what works.
Adding GHK-Cu makes the GLOW blend; adding GHK-Cu and KPV makes KLOW.
Part of the KLOW blend, and app users log the two together.
Guides pair it with ipamorelin at 200 to 300 mcg before bed, or MK-677 at 25 mg a day.
Compare TB-500
Evidence and legal status
Evidence: animal data only
For the fragment, animal data only. One fragment trial is registered: NCT07487363, Phase 1/2 for cardiovascular markers in 80 people, recruiting since 2026-02. Full-length thymosin beta-4 has real trials: an IV safety study, a Phase 2 in heart attack (90 people, completed), RGN-259 eye drops for dry eye and neurotrophic keratitis, and topical gel for venous and pressure ulcers. FDA found no human exposure data for the fragment.
FDA and WADA
Not FDA approved
An approval withdrawn, or removed from FDA's compounding lists.
Not FDA approved. The fragment (LKKTETQ) sat on the 503A Category 2 list from 2023 until 2026-04-15, removed because nominations were withdrawn. In July 2026 an FDA advisory committee recommended it for wound healing (reported 8 to 6), against staff advice. Non-binding; rulemaking is still required.
WADA 2026 S2.3 names thymosin beta-4 and its derivatives, such as TB-500, under growth factors, prohibited at all times. Validated tests for Ac-LKKTETQ have existed since 2012. Also banned in horse racing and prescription-only in Australia and New Zealand.
WADA: Prohibited
TB-500 questions
What is actually in a TB-500 vial?
It depends on who made it. The anti-doping literature defines TB-500 as the 7 amino acid fragment Ac-LKKTETQ. One seller states its TB-500 is full-length thymosin beta-4, one guide claims most of the market is the full protein, and FDA's 2026 review found products sold as TB-500 with different salts, derivatives and even different molecules. Third-party test reports found do not say which form was tested.
Is TB4 Frag the same as TB-500?
No. Products sold as TB4 Frag are usually Ac-SDKP, residues 1 to 4 of thymosin beta-4, researched for anti-fibrotic effects. One guide claims a half-life of about 4.5 minutes for it.
What is TB-500 used for?
Soft-tissue recovery: tendons, ligaments, muscles and post-surgery, usually alongside BPC-157.
How much and how often?
The common pattern is 2 to 2.5 mg twice weekly for 4 to 6 weeks, then 2 to 2.5 mg once a week. That is 4 to 5 mg a week while loading. Forums often run much higher, 10 to 20 mg a week.
How many units is 2.5 mg?
With 10 mg in 2 mL, 2.5 mg is 50 units on a U-100 syringe. Use the calculator for other mixes.
TB4 vs TB-500: what is the difference?
TB4 (thymosin beta-4) is the full 43 amino acid protein. TB-500 is a 7 amino acid piece of it. The human trials used the full protein.
What doses do people actually log?
In one tracking app with 103 TB-500 users, the most common entry was 2 to 3 mg per injection (72 logs), then 3 to 5 mg (45), 5 mg or more (25), plus a micro-dose group at 0.2 to 0.6 mg (54). 38% rated their experience favorable and 62% mixed.
Should I dose by body weight?
Usually not. One site uses a weight table with 2 to 3 mg loading doses by bracket, and one dog-scaled figure gives 0.084 mg/kg a week.
Why do I feel tired after injecting?
Fatigue is common during loading. Guides suggest injecting in the evening.
Where do I inject it?
Anywhere under the skin, usually the belly or flank. Not into the injured tendon or joint.
What if I miss a dose?
Take it within a day or skip it.
What is the half-life?
Not measured in humans for the fragment. Claims online run from minutes to 3 days with no sources. In rats, the breakdown product Ac-LKK is still detectable at 72 hours. Full-length thymosin beta-4 by IV lasted longer at higher doses in a human safety study.
Does it cause cancer?
There is no human data. Thymosin beta-4 is raised in several tumour types and linked to cancer cell migration in lab studies, so guides tell people with active or recent cancer to skip it. They also say to avoid it in pregnancy and tested sport.
Is it banned in sport?
Yes. WADA S2.3 names thymosin beta-4 and its derivatives such as TB-500, prohibited at all times.
Is it FDA approved?
No. It left the 503A Category 2 list in April 2026, and a July 2026 committee vote to recommend it is non-binding.
Ask about TB-500
Answers come from this site's pages only, with a link to each source.
Sources
40 sources, each checked by date. Record updated Oct 23, 2026. Numbers are restated in our own words and labelled by where they came from.
Clinical study4
- Esposito S et al. 2012, identification of TB-500 (Ac-LKKTETQ), Drug Test AnalPubMed · checked Oct 23, 2026
- Ruff D et al. 2010, IV thymosin beta 4 in healthy volunteers, Ann N Y Acad SciPubMed · checked Oct 23, 2026
- Tang MC et al. 2011, thymosin beta 4 induces colon cancer cell migrationPubMed · checked Oct 23, 2026
Regulatory4
- FDA to remove 12 peptides from Category 2Frier Levitt · checked Oct 23, 2026
- FDA panel votes to loosen restrictions for four peptidesPharmExec, via a news report · checked Oct 23, 2026
- WADA 2026 Prohibited ListWADA · checked Oct 23, 2026
Vendor guide1
- TB-500 10 mg product pageVendor product page · checked Oct 23, 2026
Competitor guide27
- TB-500 protocolpeptidedosingprotocols.com · checked Oct 23, 2026
- TB-500 dosage guidebodyhackguide.co · checked Oct 23, 2026
- TB-500 profilepathtopeptides.com · checked Oct 23, 2026
Community-reported4
- BPC-157 and how to stackelitefitness.com forum · checked Oct 23, 2026
- BPC-157 for sore jointselitefitness.com forum · checked Oct 23, 2026
- Elcsum's 6-month peptide and SARM logelitefitness.com forum · checked Oct 23, 2026