TB-500

Thymosin beta-4 fragment · C-tier (Dr. Alex Tatem) · Preclinical evidence

Usually paired with BPC-157 as the “Wolverine stack”. The human data is for the full thymosin β4 protein (eye drops, wound healing). TB-500 is a different, smaller fragment that has never been tested in people.

Dr. Tatem’s take

C-tier: “half the people claiming it’s the best thing since sliced bread, other half of people saying this did nothing for me.” The eye-drop data is real; injecting it throughout the body is unproven. He rates the BPC/TB/GHK “Glow” blend C too, because “a stack is only as strong as its weakest link.”

In Dr. Tatem’s tier list

• TB-500 is a derivative of thymosin beta-4 and is often paired with BPC-157 as the “Wolverine stack” because the two act differently.
• Thymosin beta-4 works mainly through actin and the cytoskeleton — the machinery cells use to move into a wound and bridge a gap.
• “There isn’t any human data for TB 500 itself.” The parent protein helped corneal abrasions and dry eye as topical eye drops — a very different use.
• Reports split half and half; most product comes from gray-market vendors with unknown purity. No adverse signals so far — “that just means we haven’t seen them yet.”
• Verdict: C tier, “right next to its brother BPC.”

History & background

Thymosin beta-4 is a naturally occurring 43-amino-acid protein. It was identified in the late 1970s–early 1980s by Allan Goldstein’s group from “thymosin fraction 5,” a thymus extract, and sequenced in 1981. It turned out to be one of the main actin-binding proteins in nearly every cell.

RegeneRx Biopharmaceuticals developed full-length thymosin beta-4 for eye (RGN-259), skin-wound and heart applications through phase 2 trials. “TB-500” is a shorter synthetic fragment popularized in horse racing and then bodybuilding — it has never been tested in humans, and it is banned in sport (WADA S2).

Benefits

• Full-length thymosin β4 eye drops helped severe dry eye in small trials.
• Involved in cell migration and tissue repair (the actin cytoskeleton).

Risks

• No human data for TB-500 itself.
• Theoretical: pro-growth and pro-migration effects could help tumors.
• Gray-market purity is uncertain.

Dosing protocols (informational, labeled by evidence)

• Community (bro science): Community loading/maintenance — Loading 2–2.5 mg; maintenance 0.75–2 mg, SubQ, Loading 2–3x/wk; maintenance 1–2x/wk, Loading 4–6 wk, then maintenance 4–8 wk (8–12 wk total)
• Clinical trial / label: Phase 1 recombinant Tβ4 (healthy volunteers) — Single 0.05–25 µg/kg; multiple 0.5–5 µg/kg, IV, Single dose or daily, 10 days (multiple-dose arm)

Status: Not approved. FDA advisers voted 8–6–1 in July 2026 to allow compounding (wound healing). The vote isn’t binding and rulemaking is pending.

Grade and commentary: Dr. Alex Tatem. Watch: BPC-157 & TB-500: The Truth About the Wolverine Stack, The Truth About Popular Peptides (What Works, What’s Overhyped) | Peptide Tier List pt.1. Subscribe: @DrAlexTatem.