TB-500 Benefits: What the Research Shows
Last reviewed
TB-500 is marketed for healing and recovery. The catch: most of the research behind those claims was done on a different, larger molecule. Here's what's actually been studied.
The short version
- TB-500 is a short fragment of thymosin beta-4, a 43-amino-acid peptide the body makes.
- Most research is on full thymosin beta-4, not the fragment sold online.
- We found no published human trials of TB-500 itself. It isn't FDA-approved and it's banned for tested athletes.
Evidence at a glance
| Type of study | What exists |
|---|---|
| Full thymosin beta-4, in people | Some Clinical trials of thymosin beta-4 eye drops, such as a 2015 placebo-controlled phase 2 trial for dry eye. |
| TB-500 fragment, in people | None found We found no published human trials of the fragment itself. |
What TB-500 is
Thymosin beta-4 is a 43-amino-acid peptide found naturally in the body, including in platelets and some immune cells. TB-500 is a short synthetic piece of it. The FDA's 2026 compounding notice identifies it as "Thymosin Beta-4, Fragment (LKKTETQ)," a seven-amino-acid sequence. Research on the full peptide doesn't automatically apply to a fragment that's a sixth of its length.
What's been studied in people: the full peptide
The best-documented human research on thymosin beta-4 is as eye drops. In a 2015 randomized, double-masked, placebo-controlled phase 2 trial, 72 people with dry eye used thymosin beta-4 drops or placebo for 28 days. The trial's two main measures didn't differ significantly between groups, though several secondary measures, including eye discomfort and some corneal staining scores, favored the peptide. No treatment-related side effects were reported in the thymosin beta-4 group.
That's a specific use, eye drops for a specific eye condition, using the full peptide. It doesn't tell us what an injected fragment does for muscles or tendons.
What's been studied in people: TB-500
Nothing we could find. Claims about TB-500 and injury recovery rest on animal and lab research and on extrapolation from the full thymosin beta-4 molecule, not on human trials of the fragment.
FDA status and sports rules
TB-500 isn't FDA-approved. The FDA removed it from its compounding "significant safety concerns" list in April 2026, and an advisory committee recommended it for the list of ingredients compounding pharmacies can use in July 2026, against FDA staff's recommendation. The FDA hasn't acted on that. Latest status: FDA status tracker.
For athletes, the 2026 World Anti-Doping Code Prohibited List names thymosin-beta-4 and its derivatives, such as TB-500, in class S2, prohibited at all times.
Frequently asked questions
What are the benefits of TB-500?
It's marketed for healing based on research into full thymosin beta-4. We found no published human trials of the TB-500 fragment itself.
Is TB-500 the same as thymosin beta-4?
No. TB-500 is a seven-amino-acid fragment; thymosin beta-4 is a 43-amino-acid peptide.
Is TB-500 banned in sports?
Yes, class S2 on the 2026 WADA list, prohibited at all times.
How do people mix TB-500?
It's sold as a powder that's reconstituted with water. Our TB-500 reconstitution calculator does the arithmetic; it doesn't recommend an amount.
Sources
- Sosne, Ousler and McLaughlin, Thymosin beta 4 ophthalmic solution for dry eye, Clinical Ophthalmology (2015)
- Goodwin: FDA's 2026 peptide compounding changes
- Frier Levitt: FDA advisory committee peptide vote (2026)
- The 2026 Prohibited List, World Anti-Doping Code (official Dutch government publication)