What is Thymosin beta-4?
Thymosin beta-4 (Tβ4) is a naturally occurring 43-amino-acid peptide found in many tissues. It binds actin, a structural protein that cells assemble and rearrange when they change shape or move.[10][11]
Cell movement matters during repair: skin and vascular cells need to move into damaged areas and rebuild a supportive tissue environment. Tβ4 research also examines inflammatory signaling and the formation of small blood vessels.[10][1]
Full-length Tβ4 differs from the shorter LKKTETQ-region fragment commonly called TB-500. A fragment, a recombinant full-length protein and a modified delivery construct cannot share evidence or dosing simply because their names are related.[11][56] For more context, read the TB-500 and thymosin beta-4 naming explainer.
What Thymosin beta-4 is investigated for
Thymosin beta-4 evidence is grouped by practical use case and topical, injectable, oral, intravenous, inhaled, transdermal, and intraperitoneal route context. Each use case separates confidence, human evidence, animal or mechanistic support, and the practical takeaway.
Venous-ulcer healing
Topical
Venous-ulcer healing
Topical
Possible healing benefits remain formulation-specific and need confirmation.[1]
Scalp flaking and redness
Topical
Scalp flaking and redness
Topical
Corneal-surface healing
Topical
Corneal-surface healing
Topical
Dry-eye symptom relief
Topical
Dry-eye symptom relief
Topical
Recovery after myocardial infarction
Intravenous
Recovery after myocardial infarction
Intravenous
A clinically useful improvement in heart function or recovery has not been established for a general IV regimen.[7]
Intestinal inflammation and fibrosis
Oral
Intestinal inflammation and fibrosis
Oral
Evidence snapshot
Overall confidence
Human findings suggest potential benefits for specific local formulations. Mixed results limit confidence in broader treatment claims.[1][8][3]
Overall confidence is a page-level composite, not an average; it weighs evidence quality, route/molecule match, and practical limitations.
Human evidence
Human wound, eye and scalp findings are mixed and formulation-specific.[1][4][8][3]
Animal / preclinical
Cell and animal research supports actin-related cell movement and repair signaling, but clinical effects remain formulation- and condition-specific.[1][2][3][4][5]
Mechanism support
Tβ4 helps regulate the pool of actin available for cell movement. Its repair biology also involves surface-cell migration, collagen deposition and small-vessel formation.[10][11]
Forms & administration
Full-length thymosin beta-4 has investigational wound gels, 0.1% eye drops, scalp preparations and intravenous formulations. Oral, nebulized and other injectable or skin-delivery formulations remain experimental, with animal-only evidence. Concentration and application requirements are formulation-specific.[1][2][61][9][63][8][64][65][66][67][5][6][26][60][35][10]
Dosing & protocols
These ranges are general reference points, not personal dosing instructions.
Typical Range
Local formulations include 0.03% wound gel and 0.1% eye solution. Application amounts depend on the formulation.[1][8]
Frequency
Wound gel is used once daily; eye-solution schedules range from twice to six times daily, depending on the formulation and condition.[1][4][8]
Timing Considerations
Eye solution and wound gel have separate application instructions, without universal clock times.[1][4][8]
Cycle Length
Wound-gel courses run up to 84 days; the principal eye-solution courses run 28 days.[1][4][8]
Safety profile
Small wound and eye trials reported acceptable short-term tolerability or no significant adverse effects for the tested local preparations. This does not establish longer-term safety or the safety of systemic and experimental formulations.[1][8]
Regulatory status
United States
Thymosin beta-4 is not an FDA-approved drug name. Availability of a supplement or research preparation does not establish approval for a medical use.[62]
| Route | FDA drug approval | 503A compounding |
|---|---|---|
| Topical | Not Approved Thymosin beta-4 is not an FDA-approved drug name. Availability of a supplement or research preparation does not establish approval for a medical use.[62] | Not Reviewed Compounding eligibility for this specific preparation has not been confirmed. Drug approval and compounding eligibility are separate questions. |
Topical
FDA drug approval
Not ApprovedThymosin beta-4 is not an FDA-approved drug name. Availability of a supplement or research preparation does not establish approval for a medical use.[62]
503A compounding
Not ReviewedCompounding eligibility for this specific preparation has not been confirmed. Drug approval and compounding eligibility are separate questions.
International
Medicinal-product authorization outside the United States remains unconfirmed for the named preparation; status depends on the exact product and country.[62]
Sports & competition
WADA’s 2026 Prohibited List explicitly includes thymosin-beta-4 and its derivatives under S2.3, prohibited at all times.
How it works
Tβ4 helps regulate the pool of actin available for cell movement. Its repair biology also involves surface-cell migration, collagen deposition and small-vessel formation.[10][11]
These processes provide a rationale for wound and corneal-surface repair. Effects depend on the formulation and where it is delivered.[1][8][6][35]
Research gaps & open questions
What the current literature has not yet settled about Thymosin beta-4:
Larger trials need to confirm wound closure and corneal healing using prespecified primary outcomes. Secondary signals and small mid-dose subgroups cannot establish a dependable treatment effect.[1][4][8]
Longer follow-up should establish whether healed wounds or corneal defects remain closed after treatment and which patients need continued care.[1][8]
Oral, inhaled and systemic preparations need separate human absorption, dose and safety studies. Animal delivery findings cannot establish that a different route matches topical trial exposure.[35][26][6]
Common questions
Is full-length Tβ4 the same as TB-500?
Do eye-drop trials prove injectable Tβ4 works?
Is full-length Tβ4 prohibited in tested sport?
Yes. WADA’s 2026 list explicitly names thymosin-beta-4 and its derivatives under S2.3, prohibited at all times.
History & discovery
Tβ4’s repair research grew from studies of cell movement and wound closure into trials of particular topical formulations. Each development path concerns a specific preparation and condition.[10][1]
Topical and intraperitoneal full-length Tβ4 improved several repair measurements in rats, providing an early rationale for further wound research.[10]
A venous-ulcer trial and later ophthalmic studies tested local formulations in people. Preliminary signals, small samples and nonsignificant primary comparisons limit how widely their results can be applied.[1][4][8]
67 citations
Full-length thymosin beta-4 research spans wound and corneal healing, dry-eye symptoms and tissue repair. Human findings are mixed and formulation-specific, with broader repair applications remaining experimental.[1][8][3][6][56][64][65][66][52][35][37][53][49]
