TB-500 (Thymosin β4)
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Complete Research Guide
Open each section for the available evidence. Gaps are stated rather than inferred.
Overview
TB-500 (Thymosin β4) is listed as regenerative / cytoskeletal.
- •Wound healing
- •Muscle/tendon repair
- •Anti-fibrotic
- •Cardiac repair (research)
Regulatory status: Not FDA-approved; compounded/research use.
Structure & Properties
Compound: TB-500 (Thymosin β4); also known as Thymosin Beta-4, TB4-frag.
Pharmacologic class: Regenerative / Cytoskeletal.
Known delivery routes: Subcutaneous, Intramuscular.
Sequence, molecular weight, salt form, and excipient details are formulation-specific and are not listed unless verified by a manufacturer or laboratory COA.
How It Works
Sequesters G-actin → promotes cell migration; upregulates metalloproteinases for ECM remodeling; anti-apoptotic; anti-inflammatory via NF-κB inhibition.
- •Reported faster recovery from injury
- •Anti-fibrotic effects
- •Generally well tolerated in trials
Human Research
Evidence grade: Pre-clinical / Observational
Evidence is primarily preclinical or observational; human effectiveness and long-term safety are not established.
Laboratory Research
Phase I/II cardiac fibrosis trials (RegeneRx)
Preclinical findings describe biological plausibility, not proven benefit in people. Animal and laboratory doses do not translate directly to human use.
Processing & Interactions
Timing and exposure
Loading phase: 2–2.5 mg twice weekly for 4–6 weeks, then maintenance every 2 weeks. Timing of day is not critical.
Potential interactions and combinations to avoid
- •Active malignancy — angiogenic concern
Absorption, half-life, metabolism, and clearance can vary by formulation and route. Use prescribing information when an approved product exists.
Safety & Precautions
Known or reported risks
- •Fatigue
- •WADA-prohibited in sport
- •No long-term human safety data
Contraindications
- •Active malignancy (theoretical)
- •Competitive athletes under WADA
- •Pregnancy
- •Bleeding disorders or anticoagulant therapy without physician guidance (injection-site haematoma)
- •Active skin infection, cellulitis, or lipohypertrophy at intended injection sites
- •Inability to maintain sterile technique or safe sharps disposal
- •Active cancer or strong personal cancer risk (pro-angiogenic and pro-migratory activity)
- •Not FDA-approved for human therapeutic use — no verified purity, sterility, or potency standards
- •Immunocompromised or transplant patients (unverified sterility and immunogenicity risk)
- •Concurrent participation in drug-tested sport (WADA prohibited or non-cleared substance)
- •Known hypersensitivity or prior reaction to this compound or any excipient/diluent
- •Pregnancy, attempting conception, or breastfeeding unless prescribed and monitored by a physician
- •Children and adolescents with open growth plates (unless under specialist endocrine care)
- •Active or recently treated malignancy without oncology clearance
- •Use without a confirmed diagnosis, baseline labs, and licensed clinical supervision
Unknown long-term toxicity should be assumed where controlled human data are limited. Seek urgent care for a severe or unexpected reaction.
Administration & Studied Formulations
Reference range: 2–5 mg 2×/week (loading); 2 mg/week (maintenance)
Frequency: 2×/week loading → weekly maintenance
Cycling: 4–6 week loading then 4–6 weeks maintenance; cycle off ≥4 weeks.
Subcutaneous (SubQ)
Default route for most research and therapeutic peptides — best absorption for reconstituted powder.
31G × 5/16" insulin syringe (U-100). 100 units = 1 mL. Pinch skin at abdomen (2" from navel), outer thigh, or love handle. Insert at 45–90°. Rotate sites daily to prevent lipohypertrophy. Alcohol-swab site, air-dry, inject slow, hold 5 sec.
Intramuscular (IM)
Used for depot formulations, some GH secretagogues (localized delivery), and clinical protocols requiring faster systemic uptake.
23–25G × 1–1.5" needle. 1–3 mL syringe. Ventrogluteal, vastus lateralis, or deltoid. Insert 90°, aspirate (optional), inject slowly. Rotate sites weekly.
Dosing information is educational context, not a personal recommendation. Approved products must follow their label and prescriber instructions.
Applications & Related Therapies
Potentially complementary measures
- •BPC-157 — classic recovery pairing
- •GH secretagogues for structural rehab
Clinical use should account for diagnosis, approved alternatives, nutrition, activity, sleep, rehabilitation, current medicines, and appropriate monitoring.
Cases, Considerations & Ethics
Decision framework: establish the clinical goal, confirm evidence quality and legal status, screen contraindications and interactions, compare approved alternatives, define monitoring and stopping criteria, and use shared decision-making with a licensed clinician.
Case evidence: individual reports cannot establish safety or effectiveness and should not outweigh controlled trials.
Ethics: informed consent should distinguish established care from experimental use, disclose uncertainty and cost, avoid overstated claims, and never substitute research products for medically necessary care.
- Active malignancy
What is TB-500 (Thymosin β4)?
In plain words
TB-500 refers to lab-made products related to thymosin beta-4, a small protein naturally found in the body. The natural protein helps manage the internal framework that cells use to change shape and move, but fragments may not act the same way. Researchers study these substances for wound healing and muscle or tendon repair. Human evidence is limited, long-term safety is not established, and TB-500 is not FDA-approved.
Technical definition
Thymosin β4 is an endogenous 43-amino-acid peptide that regulates the actin cytoskeleton; TB-500 is a research-market name used for synthetic thymosin β4–related products, including fragments that are not equivalent to the full-length peptide. Full-length thymosin β4 binds and sequesters monomeric G-actin, supporting cytoskeletal remodeling and cell migration, while experimental studies also describe extracellular-matrix remodeling, anti-apoptotic effects, and reduced NF-κB inflammatory signaling. TB-500 is not FDA-approved and is prohibited in sport by WADA; evidence for repair applications remains largely preclinical, with no established long-term human safety profile.
Function
Dosing
Recommended Time of Day
Any time of day, 2× weekly — consistency matters more than timing.
See “Timing & Interactions” below for full fasted/fed circumstances, what to avoid combining, and what pairs well.
Administration & Technique
Injection & Application Sites
- Abdomen — 2 in (5 cm) away from the navel, either side. Fastest, most consistent SubQ absorption.
- Flank / love handle — Lateral fat pad above the hip. Good rotation site when the abdomen is tender.
- Outer thigh — Upper outer quadrant, a hand-width below the hip. SubQ pinch at 45°.
- Ventrogluteal — Palm on greater trochanter, index to ASIS — inject in the V. Safest IM site.
- Dorsogluteal (upper outer) — Upper outer quadrant of the buttock. Used for depot IM; alternate sides each cycle.
- Upper arm / deltoid — Back of the upper arm for SubQ; 2 in below the shoulder bone for IM.
- Anterior thigh (vastus lateralis) — Middle third of the outer front thigh. Preferred IM site for self-injection.
Diagram is a general illustration, not a medical instruction. Rotate sites every injection, keep 1 in (2.5 cm) between recent sites, and avoid scars, moles, bruises and the navel area.
Cycling
4–6 week loading then 4–6 weeks maintenance; cycle off ≥4 weeks.
Timing & Interactions
- ·Active malignancy — angiogenic concern
- ·BPC-157 — classic recovery pairing
- ·GH secretagogues for structural rehab
Storage & Reconstitution
Reconstitution Calculator
1 mL = 100 units on a standard U-100 insulin syringe. Draw to the nearest 0.5 unit and confirm dosing with a clinician before injection.
Your Notes
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Benefits
- ·Reported faster recovery from injury
- ·Anti-fibrotic effects
- ·Generally well tolerated in trials
Risks
- ·Fatigue
- ·WADA-prohibited in sport
- ·No long-term human safety data
Contraindications
- ·Active malignancy (theoretical)
- ·Competitive athletes under WADA
- ·Pregnancy
- ·Bleeding disorders or anticoagulant therapy without physician guidance (injection-site haematoma)
- ·Active skin infection, cellulitis, or lipohypertrophy at intended injection sites
- ·Inability to maintain sterile technique or safe sharps disposal
- ·Active cancer or strong personal cancer risk (pro-angiogenic and pro-migratory activity)
- ·Not FDA-approved for human therapeutic use — no verified purity, sterility, or potency standards
- ·Immunocompromised or transplant patients (unverified sterility and immunogenicity risk)
- ·Concurrent participation in drug-tested sport (WADA prohibited or non-cleared substance)
- ·Known hypersensitivity or prior reaction to this compound or any excipient/diluent
- ·Pregnancy, attempting conception, or breastfeeding unless prescribed and monitored by a physician
- ·Children and adolescents with open growth plates (unless under specialist endocrine care)
- ·Active or recently treated malignancy without oncology clearance
- ·Use without a confirmed diagnosis, baseline labs, and licensed clinical supervision
Regulatory
Not FDA-approved; compounded/research use
Veterinary Use (Pets)
Common in equine and canine sports rehab for soft-tissue and cardiac recovery. Loading protocol then maintenance.
Functional Groups
Cited Works
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