Immune & inflammation
Thymosin alpha-1
A thymic immune peptide approved in dozens of countries for specific indications, but never approved in the US — and marketed far beyond any approval.
- How settled this rating is:
- moderate confidence in the current evidence rating
- Routes studied:
- Subcutaneous injection
- Also known as:
- thymalfasin, Zadaxin, Tα1
- Last reviewed:
- 2026-08-23
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Evidence passport
Thymosin alpha-1
A one-screen evidence identity for this compound. These fields describe research maturity, confidence and legal status. They are not a safety guarantee, efficacy percentage or recommendation.
- Evidence level
- L3Early human studies
- Confidence
- Moderate confidence in rating
- Regulatory status
- Approved in some countries only · See jurisdiction details
- Development status
- Approved
Evidence strength
Higher = more and better-quality human evidence. It does not mean the effect is bigger or that the compound works for you.
Higher = more mature, better-documented human safety data. It does not mean the compound is safer than one with a lower number.
The 0-100 values rate the strength and maturity of evidence, not how effective or safe the compound is.
- Evidence base
- Includes human studies
- Furthest established stage
- Approved
- Human research maturity
- Approved in multiple non-US regions for specific indications; studied in oncology and infectious disease settings
- Source curation
- Sources fully curated
Routes recorded
Overview
Higher = more and better-quality human evidence. It does not mean the effect is bigger or that the compound works for you.
Higher = more animal, tissue or cell research. Preclinical results are a starting point, not proof of a human benefit.
Higher = more mature, better-documented human safety data. It does not mean the compound is safer than one with a lower number.
How to read these scores
Every number here rates the evidence, not the compound. They are editorial 0-100 strength ratings, not percentages, and not a rating out of five stars.
- Human efficacy evidence strength — Higher = more and better-quality human evidence. It does not mean the effect is bigger or that the compound works for you.
- Preclinical evidence strength — Higher = more animal, tissue or cell research. Preclinical results are a starting point, not proof of a human benefit.
- Human safety evidence strength — Higher = more mature, better-documented human safety data. It does not mean the compound is safer than one with a lower number. A score of 80 does not mean “80% safe”.
- Evidence level (L0-L5) — the strongest type of study behind the compound, from anecdote (L0) to large replicated human trials (L5). It is a description of the study evidence, not a quality, safety or recommendation rating.
- Confidence — how likely we think it is that this rating changes as new research lands. Low confidence means the picture is unsettled, not that the compound is bad.
None of these ratings is medical advice, a safety guarantee, or a recommendation to use anything. How we grade evidence.
How far human research has progressed: Approved in multiple non-US regions for specific indications; studied in oncology and infectious disease settings
Routes & formulations
Studied / approved routes
Approved products abroad (e.g. thymalfasin) are subcutaneous injections for their specific licensed indications. Anything else sold online is outside approved supply.
Route availability is not evidence of efficacy, and evidence from one route does not transfer to another. The Registry never provides dosing or sourcing information.
Peptide lifecycle
Discovery
Preclinical
Phase I
Phase II
Phase III
Approved
Approved in parts of Asia-Pacific, Latin America, Eastern Europe and the Middle East for various indications; never approved by the FDA.
What it is
A 28-amino-acid peptide originally isolated from thymic tissue, developed as an immune-response modifier.
What people claim
- Boosts immune function
- Adjunct benefit in hepatitis and some cancers
- General immune 'optimisation' in healthy people
What the evidence actually says
This is a real medicine in many countries with genuine clinical trial history — which makes it the most over-extrapolated compound in its class. Region-specific approvals for defined diseases do not translate into evidence for healthy-person immune enhancement, and the FDA has never approved it.
Related evidence
Useful next reads based on this compound — not recommendations.
- Related compound
KPV evidence profile
A three-amino-acid fragment of alpha-MSH marketed for gut healing and inflammation, with no human clinical studies identified by the FDA.
- Compare
Compare Thymosin alpha-1 vs KPV evidence
Same questions, same fields, side by side — including how much human evidence exists.
- Checked claim
Claim review: “KPV has human clinical evidence for gut healing.”
A closely related claim we have graded, from Gut & immune.
- Context
Safety Centre
What approved, investigational and unapproved actually mean for documented human safety.
Human evidence
- Clinical trials in hepatitis B/C and as an adjunct in some oncology settings, largely supporting its regional approvals.
- No evidence base supporting general 'immune boosting' in healthy people.
Preclinical evidence
- Immune cell assays and animal models of infection and tumour immunology.
Animal and cell findings are Level 1–2 evidence.
Mechanism and pathways
- Modulates T-cell maturation and dendritic-cell function; effects on TLR signalling described.
Safety and unknowns
- Generally described as well tolerated within its approved indications abroad.
- Products sold outside approved supply carry unverified quality.
Cancer relevance
This section covers questions raised by how the compound works in the body, plus anything regulators and trial teams keep an eye on. It is not a statement that this compound causes cancer — for most compounds here, no human data exist in either direction.
Monitored in trials; not demonstrated in humans
Regulatory status
Regulatory decisions apply to specific jurisdictions, products, formulations and indications. An approval elsewhere is not automatically an approval in your country.
Check the regulatory note and linked primary sources for jurisdiction-specific details.
Not FDA-approved. The FDA's 2024 advisory review notes approvals in parts of Asia-Pacific, Latin America, Eastern Europe and the Middle East for various indications. Those approvals are region- and indication-specific; they do not generalise to 'immune boosting' in healthy people or to US availability.
Evidence grade
Preliminary human outcome research, including small or observational studies. Descriptive exposure studies alone do not demonstrate therapeutic benefit.
What would change our rating?
- A regulatory decision in a major Western region.
- Large independently run trials in the marketed use cases.
References and sources
Source transparency
A provenance snapshot of this profile. Counts show what kinds of sources are cited, not how much scientific weight each source deserves.
- Last editorial review
- 2026-08-23
- Recently reviewed · 54 days ago
- Linked curated sources
- 1
- Sources still pending
- 0
- External specialist reviews
- 0
- None recorded for this profile
Review provenance
Registry editorial review: Colin Jackson-White, creator and editor, who is not a doctor or clinician. External specialist review is credited only when a named reviewer has completed a review of this exact profile.
Literature-discovery and AI tools may help locate or challenge candidate evidence, but they are not counted as evidence sources here. Registry judgements are tied to the underlying papers, trial records, regulator documents and official study records.
- Regulatory / labelFDA — Thymosin alpha-1 briefing material (PCAC 2024)
Source hierarchy: regulatory documents and trial registries first, peer-reviewed work next, sponsor material flagged as non-independent. We never use supplier or clinic marketing as evidence, and where a verified source has not yet been curated we say so rather than inventing one.
Evidence change history
These entries record changes to our assessment of the published evidence — not changes to the compound itself.
No recorded changes yet. Baseline position set on 2026-08-23.