Investigational thymosin beta-4-derived heptapeptide
TB-500
aka TB500 · N-acetylated thymosin beta-4 fragment 17–23 · Ac-LKKTETQ
User reports
approximate — combined from two independent Reddit reads
Men 45–60
0 men aged 45–60
No reports in this group yet.
All men
2 men
small sample · n = 2Outcome negative 1 of 2 · unclear 1 of 2
Side effects other 1 of 2
Why stopped side effects 1 of 2
Everyone
11 people
- Positive: 4 of 11 (36%)
- Negative: 3 of 11 (27%)
- No effect: 2 of 11 (18%)
- Unclear: 2 of 11 (18%)
| Item | Reports |
|---|---|
| Injury healing | 4 of 11 (36%) |
| Joints / tendons | 4 of 11 (36%) |
| Inflammation | 2 of 11 (18%) |
| Recovery | 1 of 11 (9%) |
| Item | Reports |
|---|---|
| Heart rate up | 2 of 11 (18%) |
| Insomnia | 2 of 11 (18%) |
| Other | 1 of 11 (9%) |
| Item | Reports |
|---|---|
| Side effects | 2 of 11 (18%) |
| No effect | 1 of 11 (9%) |
User reports are anecdata, not evidence: self-selected, unverified, often combined with other compounds.
In their words
“Gave me massive brain fog and overall just an unwell feeling”
“It causes me crazy heart thumping all night long.”
“I have better range of motion and 80% less pain than I had three weeks before.”
“I didn't notice a difference with TB-500, and prefer only BPC-157. Took a few weeks.”
“BPC-157 + TB500 current results 40M. I started BPC-157 & TB500 7 days”
“I've tolerated many others (including CJC+Ipa and TB-500) fairly well in the past.”
Read summaries and method notes
Read 1. No man aged 45–60; the only explicit man (25M) had a strongly negative first dose — emotional blunting, severe brain fog, feeling unwell after 500 mcg, later finding the clinic vial past date. Of nine users, four improved (pain, inflammation, range of motion, recovery), two noticed nothing, three were negative; almost all favourable reports also used BPC-157. Two on BPC/TB had pounding heart and broken sleep.
Read 2. No man aged 45–60; the only stated man was 40M, 7 days into BPC-157 + TB-500 with an unclear outcome. The second user, a woman, had tolerated TB-500 fairly well before a severe reaction to sermorelin. Two seed threads were on excluded r/BodyHackGuide. Too sparse to conclude anything.
Note 1. Nearly all favourable reports used BPC-157 concurrently. The one TB-500-only male report involved a past-date clinic vial.
Note 2. Two seed threads were excluded as r/BodyHackGuide. Typical use is stacked with BPC-157.
Each read counted people independently. Overlap between the two reads is estimated from shared threads and removed; counts are approximate. How we count.
Summary
TB-500 here refers to the N-acetylated LKKTETQ fragment of thymosin beta-4, not the full-length 43-amino-acid peptide. Product naming can be ambiguous. Human repair benefits and the prior overall ranking are not established by fragment trials. Identity study.
Proposed mechanism
The proposed actin binding/buffering, cell migration, epicardial progenitor, NF-κB, autophagy and neurogenesis effects require exact-molecule and preclinical qualification; full-length thymosin beta-4 findings cannot simply be assigned to the fragment. “Actin formation” is an oversimplification. A 2024 cell study found wound closure with a metabolite, not the parent fragment. Study; FDA review.
Safety
- Human adverse-event rates and safe doses are unknown.
- Immunogenicity, aggregation and peptide impurity risks remain unresolved.
- Full-length thymosin beta-4 safety findings cannot validate fragment injections.
- Long-term, reproductive and carcinogenic safety information is insufficient.
From labels, regulators and trials. No signal in small studies ≠ safe.
Legal status
US FDANot approved
Not approved; favorable July PCAC recommendation; October HHS draft/interim policy. July 23, 2026 PCAC favored both forms; FDA staff opposed listing. Removed from Category 2 April 22. October HHS text specifies acetate SC/IM under conditions; Federal Register describes draft policy. Finalization/final 503A rule not found. Source
checked 2026-11-13EU
FDA's 2026 foreign-status review reports no EMA-authorized TB-500 medicine; current independent EU authorization not found. Source
checked 2026-11-13Re-check pending: HHS interim policy is a draft; re-check after the comment period.
Evidence D injected TB-500 fragment for injury recovery
D stands. No human trial of the LKKTETQ fragment exists (FDA's 2026 review found none). Trials of full-length thymosin beta-4 are a different molecule and do not count - the same rule is applied to MOTS-c/CB4211 and fragment 176-191/AOD-9604.
Human trials · 0
No human trials found for the marketed use.
Dose ranges
Reported ranges from labels and studies, with context. Not a recommendation.
No data.
Editorial ratings EDITORIAL
Editors’ judgement, 0–5. Opinion, not data; separate from grade and user score.
Sources
- hhs.gov/sites/default/files/hhs-503a-peptide-enforcement-discretion-policy-appendix-b.pdf
- wada-ama.org/sites/default/files/2025-09/2026list_en_final_clean_september_2025.pdf
- fda.gov/media/193349/download
- fda.gov/media/193343/download
- fda.gov/drugs/human-drug-compounding/certain-bulk-drug-substances-use-compounding-may-pres
- govinfo.gov/content/pkg/FR-2026-10-30/html/2026-22192.htm
- fda.gov/advisory-committees/advisory-committee-calendar/july-23-24-2026-meeting-pharmacy-c
- ema.europa.eu/en/medicines
- pubmed.ncbi.nlm.nih.gov/23084823/
- pubmed.ncbi.nlm.nih.gov/20536470/
- pubmed.ncbi.nlm.nih.gov/26056426/
- pubmed.ncbi.nlm.nih.gov/10469335/
- pubmed.ncbi.nlm.nih.gov/38382158/
- pubmed.ncbi.nlm.nih.gov/42542926/
Reddit threads read · 5
Research checked 2026-11-13.