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This entry or formulation may be investigational and may not correspond to an FDA-approved product; safety and efficacy may not have been established. Kairo lists it for identification and record-keeping only.
Overview
Product & regulatory status
Research entry: inclusion is for identification, not approval or a recommendation to use it. Verify the exact product and current US status with a pharmacist.
What the evidence shows
Fragment versus full-length peptide
FDA identifies TB-500 as the LKKTETQ fragment and reports no identified human exposure data for that fragment in its safety summary. [1]
Why eye-drop results do not transfer
A randomized dry-eye study tested full-length thymosin beta-4 in an ophthalmic formulation. That is a different molecule and exposure from the TB-500 fragment. It cannot establish benefits from TB-500 injections for muscle or tendon recovery. [2]
What remains unknown
Studies of full-length thymosin beta-4 do not establish benefits, safety, or a recovery timeline for TB-500.
Safety
Safety uncertainty
Human safety information is limited. FDA flags immune-reaction and impurity concerns for this substance. [1]
Check the exact identity
A full-length thymosin beta-4 eye-drop paper is not a preparation guide for an injectable fragment. Matching the ingredient name loosely is not sufficient to transfer formulation or safety findings. [2]
Understanding product quality
Compounded drugs are not FDA-approved finished products. Poor preparation can cause contamination or incorrect strength. A catalog entry or a research paper is not a quality assessment of your product. [3]
When to seek urgent help
Severe allergic symptoms such as trouble breathing, throat or tongue swelling, or fainting need immediate help. Call 911 or your local emergency number. This is general emergency information, not a complete list of risks for this compound. [4]
A starting point for discussion
This is not a complete list of adverse effects or interactions. Your health history, other medicines, and the exact formulation matter. Missing safety data is not evidence of safety.
Common questions
Is TB-500 the same as thymosin beta-4?
The fragment and full-length molecule differ. Names on marketed products can be ambiguous; confirm the exact ingredient rather than transferring evidence between them.
Questions for your clinician
Does the evidence match my condition and this exact product? What risks or interactions matter for me? How would we assess whether it is helping?
Sources
- Certain Bulk Drug Substances for Use in Compounding that May Present Significant Safety RisksFDA · safety information · accessed September 2026
- Thymosin beta 4 ophthalmic solution for dry eye: a randomized, placebo-controlled, Phase II clinical trial conducted using the controlled adverse environment (CAE) model2015 · randomized eye-drop trial · 72 participants
- Compounding and the FDA: Questions and AnswersFDA · product quality and regulation
- AnaphylaxisMedlinePlus · recognizing an emergency
Educational information, not a recommendation to use a compound. Kairo does not give dosing advice. Review decisions with a licensed healthcare professional.