Also referred to as Tα1, Zadaxin, Thymalfasin
Approved in a number of countries outside the United States for specific infectious-disease indications, with a real but heterogeneous clinical literature.
Mechanism
Modulates T-cell maturation and function and dendritic-cell signalling, with reported effects on Th1 responses.
Evidence
Each statement below carries its own evidence level, its own confidence rating, and its own account of what remains unestablished. A compound does not have a single grade.
Thymosin alpha-1 has been studied in specific infectious-disease indications and is approved for some of them outside the United States.
What is not established
Trial quality is heterogeneous. Approval elsewhere is for specific indications, not for general immune enhancement.
Last evidence review: 2026-08-23
Human evidence
Human and non-human evidence are kept strictly separate. They are never pooled, averaged, or presented as a single body of support.
No human evidence on file
Pharmacology
Half-life
2 hours
Approximately 2 hours as reported in pharmacokinetic work.
Visualise this half-life →Routes studied
Evidence from one route does not transfer to another. Topical, oral, and injected administration can produce entirely different exposure from the same quantity.
Regulatory status
Not FDA-approved. Approved in a number of other countries for indications including chronic hepatitis B. Appears on FDA's list of substances raising significant safety risks for compounding purposes.
Storage as documented
Follow the labelling of the approved product in jurisdictions where one exists.
Safety
This lists what has been reported. It is not a complete safety profile, and for several compounds in this catalogue no systematic safety surveillance exists at all.
Interactions
thymosin-alpha-1 ↔ immunosuppressant medications
A compound studied for immune stimulation and a medication prescribed to suppress immune function work against each other by design. This is particularly relevant in transplant and autoimmune contexts.
Limitations. No formal interaction studies. Mechanistic opposition is the basis for the flag.
Limitations
Given as much prominence as the findings, because for most compounds in this category it is the more important half.
Reference
Multiple high-quality human trials, or strong systematic-review or meta-analytic evidence.
Human controlled evidence exists, but replication or sample size is limited.
Small human studies, observational evidence, or early-phase clinical work.
Predominantly animal or in-vitro evidence. No adequate human outcome data.
Biological plausibility or mechanistic reasoning without adequate outcome evidence.
Evidence is absent, irreconcilable, or too weak to support any directional statement.