TB-500
A powerful fragment of thymosin beta-4 that acts like your body's repair signal—speeding up healing of muscles, tendons, and tissues by promoting cell migration and new blood vessel growth right where you need it most.
Written by Michael Carroll — Owner, Director of Research · Reviewed by the Peptide Initiative Research Team · Editorial standards
Suggested dose
2 – 2.5 mg
Compound profile
Scientific & efficacy data
Healing & Recovery
Peptide profile
Moderate human trials
TB-500
2-2.5 mg · Twice weekly
Molecular formula
C38H68N10O14
- Mol. weight
- 889.01 g/mol
- CAS number
- 885340-08-9
- PubChem
- 66356057
- Developed · 1981
- Allan L. Goldstein, PhD
George Washington University School of Medicine
Amino acid sequence
Ac-LKKTETQ (N-Acetyl-Leu-Lys-Lys-Thr-Glu-Thr-Gln)Healing Speed
Accelerates tissue repair through cell migration and angiogenesis—one of the most effective peptides for injury recovery [1][5]
Tissue Repair
Regenerates muscle, tendon, and ligament tissue by promoting new blood vessel formation and reducing inflammation [1][5]
Anti-Scarring
Prevents fibroblast-to-myofibroblast conversion, reducing scar tissue formation and preserving tissue flexibility [4]
Dosing
How much do I take?
2 – 2.5 mg
2 – 2.5 mg
Covers all 2 documented dose levels · timing · dose-adjustment guidance.
Suitability
Is this right for me?
Best for accelerating injury recovery & tendon and ligament healing
Best for
Athletes Recovering from Muscle Injuries
If you've pulled a hamstring, strained your back, or torn a muscle, TB-500 helps accelerate the healing process by promoting cell migration to the injury site and supporting new blood vessel growth. It's especially useful for injuries that just won't seem to fully heal [1][5].
Tendon and Ligament Problems
Tendons and ligaments are notoriously slow healers because they have poor blood supply. TB-500 promotes angiogenesis (new blood vessel formation) and helps repair these stubborn connective tissue injuries—think Achilles tendonitis, tennis elbow, or rotator cuff issues [5].
Post-Surgical Recovery
After surgery, your body needs to repair a lot of tissue quickly. TB-500 supports wound healing, reduces inflammation, and may help minimize scar tissue formation. Some protocols use it alongside traditional recovery to potentially speed up the healing timeline [1][4].
Chronic Inflammation and Slow Healers
Some people just heal slowly—whether due to age, diabetes, or other factors. TB-500 helps regulate the inflammatory response and promotes the cellular processes needed for tissue repair. It essentially tells your body to focus healing resources where they're needed most [1].
Consider alternatives if
Do not use if
Use with caution if
Not sure?
Compare TB-500 with similar peptides to find the best fit for your goals.
Administration
How do I use it?
Subcutaneous injection · Intramuscular injection
Route
Subcutaneous injection (just under the skin)—the easiest and most common method. Some users prefer injecting near the injury site, though systemic administration works well too.
Best sites
Covers reconstitution · step-by-step technique · storage · a sample daily schedule.
Safety
Is it safe?
4 common side effects · 1 serious
TB-500 has shown a good safety profile across preclinical studies and limited human research.
It's a fragment of thymosin beta-4, a naturally occurring protein in your body involved in healing. Most side effects are mild and transient, primarily injection site reactions. However, large-scale clinical trials are still needed to fully establish its safety profile in humans [1].
TB-500 has been used extensively in equine medicine and has been the subject of multiple human clinical trials for conditions like dry eye, wound healing, and cardiac repair. Phase 1-2 trials have shown it to be well-tolerated, but Phase 3 data is limited.
[8] Always work with a healthcare provider when using research compounds [2].
Common side effects · experienced by some users
Injection site redness
A little pink or red area where you injected is totally normal. It's just your skin reacting to the needle and solution [6].
Management: Rotate injection sites between belly, thigh, and arm. A cool compress can help. Usually fades within 24-48 hours.
Mild fatigue or lethargy
Some users feel a bit tired after injections, especially in the first week. Your body is mobilizing healing resources [6].
Management: Inject in the evening if fatigue bothers you. Stay well-rested and this typically improves after the first week.
Mild headache
Occasional headaches have been reported, usually mild and in the first few days of use [6].
Management: Stay well-hydrated and rest if needed. These typically resolve within the first week as your body adjusts.
Slight flushing
Some users notice mild warmth or flushing at the injection site or generally, usually brief.
Management: This typically passes within 30 minutes. Not a cause for concern unless it's severe or persistent.
Less common
These typically resolve with continued use or dose adjustment.
Stop and seek help if
- Any signs of allergic reaction—stop immediately and seek medical help
- Persistent headaches or fatigue that don't improve after the first week
- Significant injection site reactions that spread or don't heal
- Any side effect that feels serious or really concerns you
- Your injury has healed satisfactorily
- Your research protocol/cycle is complete
TB-500 is a research compound, not an FDA-approved medication. Never start, stop, or change your dosing without guidance from a qualified healthcare provider. This information is for educational purposes only—not medical advice.
With other peptides
- Safe:BPC-157 — Excellent pairing—the classic 'healing stack.' BPC-157 works through different pathways and together they provide comprehensive tissue repair support. Inject at different sites.
- Safe:GHK-Cu — Safe to combine for comprehensive tissue repair. GHK-Cu focuses on skin and collagen while TB-500 works on deeper tissue healing.
- Safe:IGF-1 LR3 — Can be combined for enhanced muscle recovery. Both promote tissue repair through different mechanisms.
- Safe:CJC-1295/Ipamorelin — Safe to stack for overall recovery. Growth hormone releasing peptides complement TB-500's healing effects.
With medications
- Caution:Blood thinners (warfarin, heparin) — May increase bleeding at injection sites. TB-500 promotes angiogenesis which could theoretically affect clotting. Monitor closely.
- Safe:NSAIDs (ibuprofen, naproxen) — NSAIDs reduce inflammation which is part of the healing process TB-500 supports. May reduce effectiveness—use sparingly.
- Safe:Corticosteroids — Steroids can impair healing. If you're on long-term steroids, discuss with your doctor.
- Safe:Diabetes medications — TB-500 supports wound healing in diabetics but monitor blood sugar as healing processes can affect glucose.
With supplements
- Safe:Collagen peptides — Complementary—collagen provides building blocks while TB-500 promotes the repair process.
- Safe:Omega-3 fatty acids — Safe and potentially beneficial. Omega-3s support anti-inflammatory pathways that complement healing.
- Safe:Vitamin C — Supports collagen synthesis and healing. Good addition to a recovery protocol.
- Safe:Turmeric/Curcumin — Anti-inflammatory but work differently than NSAIDs. Generally considered safe to combine.
Effectiveness
How do I know it's working?
Moderate human trials · first signs week 1
Evidence level
Moderate human trials
(Phase 1-2)
Regulatory status
Research compound
Onset of effects
Moderate
(1-2 weeks)
How it works
Think of TB-500 as your body's 'come here and help' signal for healing.
When you get injured, your body naturally releases thymosin beta-4 to start the repair process. TB-500 is a synthetic version of the most active part of this protein.
It works by telling your cells to migrate to the injury site, promoting the growth of new blood vessels to bring oxygen and nutrients, and reducing inflammation so healing can happen properly.
It also helps prevent excessive scar tissue formation, so you heal with more functional tissue instead of stiff scar tissue. It's like giving your body's repair crew a megaphone and extra supplies [1].
The deeper mechanism
TB-500 (Ac-LKKTETQ) is a synthetic heptapeptide corresponding to the active region (17-23) of thymosin beta-4 (Tβ4). Its primary mechanism involves sequestration of G-actin monomers, regulating actin polymerization and enabling cytoskeletal reorganization necessary for cell migration.
TB-500 upregulates actin expression and promotes the formation of extracellular matrix proteins through activation of cell surface receptors. The peptide stimulates angiogenesis through the VEGF/Akt/eNOS pathway, promoting endothelial progenitor cell differentiation and blood vessel formation.
It exhibits anti-inflammatory properties by reducing macrophage infiltration and downregulating pro-inflammatory cytokines including TGF-β and IL-10.
TB-500's anti-fibrotic effects occur through inhibition of fibroblast-to-myofibroblast differentiation, mediated partly by its N-terminal sequence Ac-SDKP.
The peptide also demonstrates neuroprotective properties by reducing apoptosis, promoting oligodendrogenesis, and supporting neural stem cell differentiation. These multi-pathway effects make it a comprehensive tissue repair and regeneration agent [1].
What to expect
Week 1
What you might notice
- Mild injection site redness (totally normal)
- Possibly some initial fatigue or mild headache
- Slight reduction in inflammation at injury site
- Your body is just getting introduced to the peptide
What's normal
- Minor injection site reactions that fade within a day
- Feeling a bit tired on injection days
- No dramatic changes yet—healing takes time
What's next
- Keep following your protocol consistently
- Track any changes in your injury or range of motion
- Side effects typically improve after the first week
Weeks 2-3
What you might notice
- Reduced stiffness around the injury
- Improved flexibility or range of motion
- Decreased pain with movement
- Less swelling if inflammation was present
What's normal
- Gradual improvement rather than sudden changes
- Good days and less-good days are normal
- Injury still present but progressing
What's next
- Continue your protocol through the full cycle
- Begin gentle movement or rehab exercises if appropriate
- Don't push the injury too hard yet
Weeks 4-6
What you might notice
- Significant improvement in injury healing
- Better function of the affected area
- Reduced or resolved pain
- Ability to return to normal activities gradually
What's normal
- Major improvement for most users by week 4-6
- Some stubborn injuries may need extended protocols
- Complete healing of muscle injuries, continued progress on tendons
What's next
- Complete your cycle and assess results
- Transition to maintenance dose if needed
- Resume full activity cautiously with proper rehabilitation
Signs it's working
Injury Recovery Indicators
- Reduced pain at the injury site
- Improved range of motion in affected joints
- Decreased stiffness, especially in the morning
- Less swelling and inflammation
- Better function during daily activities
Healing Progress
- Wounds closing more quickly than expected
- Reduced bruising duration
- Faster return to physical activities
- Less need for pain medication
- Improved tissue flexibility
Physical Performance
- Ability to exercise without aggravating injury
- Improved strength in previously injured area
- Better recovery between workouts
- Reduced compensation patterns from injury
Not seeing results? Common reasons
- Not giving it enough time—TB-500 works over weeks, not days. Tendons especially take 4-8 weeks to show major improvement
- Dose too low for the injury severity—stubborn injuries may need higher loading doses initially
- Poor quality peptide from unreliable source—always get third-party testing certificates (COAs)
- Improper storage degraded the peptide—check if your solution looks clear before using
- Still aggravating the injury with activity—healing peptides work best when you give the injury rest
- NSAIDs blocking the healing process—these anti-inflammatory drugs can interfere with tissue repair signals
Key research
Questions
Frequently asked
What's the difference between TB-500 and thymosin beta-4?
Thymosin beta-4 is the full 43-amino-acid protein naturally produced in your body. TB-500 is a synthetic 7-amino-acid fragment (the 'active region') that contains most of the healing benefits. Think of it like using the key part of a larger molecule. TB-500 is easier to synthesize and more stable, which is why it's commonly used in research [1].
Can I inject TB-500 directly into my injury?
You can inject near the injury site (within a few inches), and some users believe this provides localized benefits. However, TB-500 works systemically—it spreads throughout your body via your bloodstream. Subcutaneous belly injections work just as well because the peptide naturally migrates to where it's needed. Don't inject directly INTO injured tissue [1].
How long until I notice healing improvements?
Most users notice reduced inflammation and improved flexibility within 1-2 weeks. Significant healing improvements typically appear by weeks 3-4 for muscle injuries. Tendon and ligament injuries take longer—expect 4-8 weeks for noticeable progress. The more severe the injury, the longer it takes.
Should I combine TB-500 with BPC-157?
This combination is very popular [12] and often called 'the healing stack.' They work through different mechanisms: TB-500 promotes cell migration and blood vessel formation, [10][11] while BPC-157 works more locally and affects growth factors differently. Together they provide comprehensive tissue repair support. Inject at different sites [6].
Will TB-500 help an old injury that never fully healed?
Possibly, yes. TB-500 can help restart the healing process in chronic injuries by promoting cell migration, new blood vessel formation, and tissue remodeling. However, very old injuries with significant scar tissue may have limited improvement. It's worth trying, especially combined with physical therapy [1].
Is TB-500 banned in sports?
Yes, TB-500 (and thymosin beta-4) are prohibited by WADA (World Anti-Doping Agency) and most sports organizations under the category of peptide hormones and growth factors. Athletes subject to drug testing should not use TB-500 [7].
Can I use TB-500 for general recovery, not just injuries?
Some users report improved overall recovery from exercise and general well-being. However, TB-500 is primarily studied for injury healing. If you're looking for general recovery support without an injury, other peptides like BPC-157 or growth hormone secretagogues might be more appropriate.
How does TB-500 reduce scarring?
TB-500 prevents fibroblasts from transforming into myofibroblasts—the cells that produce excessive scar tissue. It also reduces TGF-beta, a major driver of fibrosis. The result is that injured tissue heals with more normal, functional tissue rather than stiff scar tissue [4].
What is TB-500?
TB-500 is a synthetic fragment of thymosin beta-4, a naturally occurring healing protein found in nearly all human and animal cells. The fragment reproduces the parent protein's active region, which promotes cell migration, blood-vessel formation, and reduced inflammation at injury sites. In research settings it's studied for muscle, tendon, and ligament recovery — it acts systemically, traveling through the body rather than working only where injected. See the full profile below for mechanism and studies, or the TB-500 vs thymosin beta-4 comparison for how the fragment differs from the full protein [1].
What is the typical TB-500 dosage?
Research protocols typically run in two phases: a loading phase of 2–2.5mg injected subcutaneously twice weekly (commonly 4–6 weeks), then a maintenance phase of 2–2.5mg once weekly. Athletes and bodybuilders researching recovery generally follow the same structure — the loading phase during active injury recovery, maintenance after. TB-500's long half-life is why dosing is weekly rather than daily. See the dosing protocol page for schedules, timing, and adjustment guidance [6].
What are the side effects of TB-500?
Reported side effects in research use are generally mild: injection-site redness, temporary fatigue or lethargy, mild headache, and slight flushing are the most common. Less commonly, a brief head rush or lightheadedness and temporary nausea have been reported shortly after injection. As with any peptide, allergic reaction is possible [9] and is the one serious reaction to watch for — discontinue and seek medical care for signs like difficulty breathing or significant swelling. The safety section below covers management for each [6].
Further reading
History & related research
History · since 1966
The Body's Master Healer — From Horse Racing Scandal to Medical Marvel
Discovered in a gland the size of a walnut, this 43-amino-acid peptide tells your body how to repair itself. Its journey from calf thymus to banned substance to promising medicine is one of science's most dramatic tales.
Read the full history of TB-500Ready for the protocol?
Every dosing tier, administration route, timing note, and dose-adjustment rule for TB-500, on one page.