TB-500 Dosage: Reported Protocols and the Thymosin Beta-4 Evidence
TB-500 protocols are quoted in milligrams per week with a confidence the evidence does not support. The peptide people are buying is also not quite the molecule the human trials studied.
There is no established TB-500 dose. No human dose-finding or efficacy trial of TB-500 has been published, and TB-500 itself is a synthetic fragment of thymosin beta-4 (Tβ4) rather than the full protein tested in clinical research. Community protocols commonly describe a loading phase of roughly 2–5 mg per week, split into two injections, for four to six weeks, followed by a lower maintenance amount — figures that come from user practice and supplier panels, not from trials. Full-length Tβ4 has been studied in humans for dry eye disease and pressure ulcers, but at doses and by routes that say nothing about injecting a fragment for tendon repair. WADA prohibits TB-500 at all times.
Amounts reported for TB-500 and studied for thymosin beta-4
| Use case | Amount reported in sources | What to know |
|---|---|---|
| Commonly reported loading protocol | Roughly 2–5 mg per week, usually split into two subcutaneous injections | Circulating user practice. Not derived from any published human study of TB-500. Source |
| Commonly reported maintenance protocol | Roughly 2 mg per month after a four to six week loading phase | Also user practice; no pharmacokinetic data in humans support this schedule. Source |
| Thymosin beta-4 in dry eye trials | Topical eye drops at defined concentrations, several times daily | A different molecule, a different route and a different indication — not transferable to injected TB-500. Source |
| Thymosin beta-4 in wound and ulcer trials | Topical gel formulations in controlled studies | Investigated for pressure ulcers and epidermolysis bullosa; no product reached approval. Source |
Figures are amounts reported in the cited sources, not a personal recommendation. Your own amount depends on your health, medicines and blood work.
TB-500 and thymosin beta-4 are not the same thing
Thymosin beta-4 is a naturally occurring 43-amino-acid protein involved in actin binding, cell migration and wound repair. TB-500 is a short synthetic peptide corresponding to the active actin-binding region of that protein. Vendors use the names interchangeably; the molecules are not interchangeable.
This matters directly for dosing. When someone points to a clinical trial as evidence that TB-500 is safe or effective, the trial almost certainly studied full-length Tβ4, usually applied topically to an eye or a wound, at doses that have no relationship to a milligram-per-week subcutaneous protocol.
It also matters for what you are buying. A vial labelled TB-500 may contain the fragment, the full protein, a different fragment, or a mixture, and there is no regulatory body checking.
- Tβ4: 43-amino-acid natural protein, studied topically in humans
- TB-500: synthetic fragment of the actin-binding region
- Trial evidence for one is not evidence for the other
- Vial contents are unverified in an unregulated market
What has actually been tested in people
Full-length thymosin beta-4 reached clinical trials for dry eye disease, corneal wound healing, pressure ulcers and epidermolysis bullosa wounds. Those programmes generated genuine human safety exposure and some encouraging signals, but none produced an approved product, and all used topical delivery to the tissue being treated.
For the use that drives almost all TB-500 sales — accelerating recovery from tendon, ligament or muscle injury in otherwise healthy adults — there is no completed published human trial of either molecule. The supporting evidence is animal work, principally in rodents and in equine tendon models.
Horse racing is where TB-500 has had the most real-world regulatory attention, and not favourably: it has been the subject of positive tests and regulatory action in several racing jurisdictions.
- Human Tβ4 studies: dry eye, corneal wounds, pressure ulcers, EB wounds
- All topical; none produced an approved medicine
- No human trial in sports injury for TB-500
- Well documented as a doping agent in equine sport
Regulatory position and anti-doping
TB-500 is not an approved medicine anywhere and is sold as a research chemical. In the United States, the FDA has placed thymosin beta-4 on the Category 2 list of bulk drug substances raising significant safety risks for compounding, which closes the compounding-pharmacy route.
WADA prohibits TB-500 at all times. It is detectable in modern anti-doping assays, and the milligram quantities in typical protocols are far above analytical thresholds.
For anyone subject to testing — including masters-level competitors, tactical athletes and many employer programmes — this is the decisive fact, independent of any question about whether the peptide works.
- Not approved as a medicine in any major jurisdiction
- Thymosin beta-4 sits on the FDA Category 2 compounding list
- WADA prohibited at all times
- Detectable at the quantities protocols describe
What a careful person records
If someone is going to use an unstudied compound, the least they can do is generate usable information. That means writing down the reconstitution maths — how much bacteriostatic water went into how many milligrams of powder — because most dosing errors in peptide use are arithmetic errors, not judgement errors.
It also means choosing one outcome that can be measured the same way every week: pain on a fixed movement, range of motion measured against a wall, or return-to-load milestones. Soft-tissue injuries improve on their own over the same four to six weeks a protocol runs, and without a baseline there is no way to separate the two.
Finally, record any injection-site reaction, and stop if there is systemic illness. Sterility problems with self-reconstituted vials are a more immediate risk than anything pharmacological.
- Write the reconstitution maths down before drawing anything
- Track one outcome, measured identically each week
- Expect natural healing to confound the picture
- Treat fever or spreading redness as a medical problem, not a side effect
What the published studies found
Each entry below links straight to the paper or the health authority page so you can read the original rather than take our word for it.
- Thymosin beta-4 clinical programme
Registered human trials in dry eye, corneal wounds and pressure ulcers
Full-length Tβ4 was investigated topically in several indications with human safety exposure recorded; no product reached marketing approval.
- TB-500 in humans
Literature search of indexed clinical trials
No completed randomised human efficacy trial of the TB-500 fragment has been published for musculoskeletal injury.
- Animal tendon and wound models
Rodent and equine studies of thymosin beta-4 and its fragment
Reported improvements in cell migration and tissue repair in animal models, which is the basis of the human claims made for the peptide.
Side effects reported in the literature
Commonly reported
- Injection-site redness, swelling or discomfort reported by users
- Head-rush or light-headedness shortly after injection, reported anecdotally
- Fatigue and headache, reported anecdotally
Serious, seek medical advice
- No controlled human safety dataset exists for the injected fragment
- Infection risk from self-reconstitution and non-sterile technique
- Cell-migration and angiogenic mechanisms are unstudied in people with cancer
- Unregulated product may be mislabelled, impure or contaminated with endotoxin
Summarised from FDA — Category 2 bulk drug substances. Report anything unexpected to your own doctor or pharmacist.
Interactions to check with a pharmacist
| Medicine or condition | What sources report |
|---|---|
| Anticoagulants and antiplatelet drugs | Higher bruising and haematoma risk at injection sites; no formal interaction studies exist. Source |
| Active or prior malignancy | Promotion of cell migration and new vessel growth has not been assessed for safety in people with tumours. Source |
| Anti-doping programmes | Prohibited at all times by WADA; detectable at typical protocol quantities. Source |
This is not a complete interaction list. Check your own medicines with a pharmacist before combining anything.
This page is reference material, not medical advice. Supplements interact with prescription medicines and with each other. Talk to a doctor or pharmacist before starting anything, especially if you are pregnant, breastfeeding, managing a health condition or taking prescription medicine.
Frequently asked questions
What is the standard TB-500 dose?
There is no standard dose. No human dose-finding trial has been published. Protocols circulating online typically describe 2–5 mg per week split into two injections for four to six weeks, then a smaller maintenance amount, but those figures come from user practice rather than research.
Is TB-500 the same as thymosin beta-4?
No. Thymosin beta-4 is a 43-amino-acid natural protein; TB-500 is a synthetic fragment of its actin-binding region. Human trials studied the full protein, usually applied topically, so those results do not transfer to injected TB-500.
Has TB-500 been tested in humans?
Not for musculoskeletal injury. Full-length thymosin beta-4 was tested in humans for dry eye disease and for pressure ulcers and other wounds, all topically, and none of those programmes produced an approved product.
Is TB-500 banned in sport?
Yes, WADA prohibits it at all times, and it is detectable in modern assays at the quantities protocols describe. It has also been the subject of positive tests and regulatory action in horse racing.
Is TB-500 legal to buy?
It is sold labelled for research use only and is not an approved medicine in any major jurisdiction. Thymosin beta-4 is on the FDA Category 2 list of bulk substances raising significant safety risks for compounding.
What are the risks of TB-500?
The pharmacological risk profile is unknown because there is no controlled human dataset. The concrete risks are infection from self-reconstitution, mislabelled or contaminated product from an unregulated market, and unstudied effects in anyone with a history of cancer.
How does TB-500 compare with BPC-157?
Both are unapproved research peptides used for soft-tissue recovery, both rest on animal evidence, and both are prohibited in sport. BPC-157 has a larger rodent literature; TB-500's parent protein has more human safety exposure, though only in topical formulations for unrelated indications.
Keep reading
Sources
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