Thymulin
Immune, Anti-Inflammatory
In short
- A zinc-dependent thymic nonapeptide — biological activity requires zinc, and the peptide is inactive without it.
- Circulating levels decline sharply with age as the thymus involutes, which is the basis for interest in it.
- Preclinical work covers immune modulation and, notably, analgesic and anti-inflammatory effects.
- No human clinical trial of administered thymulin has been completed.
- Frequently confused with thymosin alpha-1 and thymalin, which are different peptides with different evidence bases.
Structure
How it works
Thymulin is a nonapeptide secreted by thymic epithelial cells. Its defining feature is zinc dependence: the peptide only adopts its active conformation when bound to zinc, so zinc status directly determines biological activity. Zinc deficiency reduces active thymulin regardless of peptide levels.
Its described role is in T cell differentiation and maturation. Preclinical work also reports anti-inflammatory and analgesic effects, with mechanisms involving cytokine modulation.
What the research shows
Animal studies report restoration of immune parameters in thymectomised and aged animals, plus anti-inflammatory and analgesic effects in inflammatory pain models.
Human data is limited to observational work on endogenous thymulin levels in ageing, zinc deficiency, and disease states.
No trial of administering thymulin to humans has been completed.
Dosing in the literature
Figures below are quoted from published studies, with the species or population they were measured in. They are records of what was studied, not recommendations.
| Studied in | Amount | Route | Source |
|---|---|---|---|
| Rodent — immune restoration and analgesia models | Nanogram to microgram ranges depending on model | intraperitoneal or intravenous | PubMed |
Commonly reported ranges
These are amounts people report using. They are not from any study, have not been evaluated for safety, and are reproduced here only because they circulate widely and are better seen alongside the evidence than instead of it.
| Reported by | Amount | Route |
|---|---|---|
| Commonly reported | 1–2 mg daily in short courses | subcutaneous |
No published human pharmacokinetic study establishes a dose, interval, or duration for this compound. Community figures below have no trial behind them and are reports of practice, not evidence. Community doses are several orders of magnitude above the amounts used in the rodent literature. Zinc status is also directly relevant to whether the peptide is active at all, which is unusual and rarely mentioned.
Handling and storage
Supplied as a lyophilised powder requiring reconstitution with bacteriostatic water. The powder is comparatively stable; once reconstituted it is refrigerated and used within weeks. Track the date you reconstitute each vial — the Inventory section does this, and it is the difference between knowing a vial is three weeks old and guessing.
Subcutaneous injection is the community route. Given the zinc dependence, adequate zinc status is mechanistically necessary for any activity at all.
Side effects
No human safety data exists for administered thymulin. Preclinical work has not reported significant toxicity.
As with any immunomodulator, autoimmune conditions are the theoretical concern.
Community reports are sparse, which reflects low usage rather than established safety.
Combinations
No interaction data. Frequently combined with other thymic peptides in community protocols, which stacks compounds with overlapping and poorly characterised effects.
Zinc adequacy is the one genuinely relevant co-factor.
Research status
A real but modest literature dating to the 1970s, largely French and Argentinian groups, on thymic endocrinology and zinc-dependent immune function.
Interest has been sustained more by the ageing and immunosenescence field than by therapeutic development. No clinical programme has advanced.
Legal status
Not approved for any indication in any jurisdiction. Sold for research use only.
WADA status
Not specifically named on the Prohibited List. Falls under WADA class S0, which prohibits any pharmacological substance not currently approved by any governmental regulatory health authority for human therapeutic use. Treat it as prohibited in sport.
Conclusion
Thymulin is real thymic endocrinology with a genuine and unusual mechanism — zinc dependence is not something most peptides have.
It has never been trialled in humans as a therapy, and the doses circulating in community use are far above anything the animal literature used. Those two facts together are the whole picture.
Sources
Track your own Thymulin protocol
Peppers logs your doses, models your levels from this half-life, tracks your vials and tells you when you will run out. Free on iPhone.
Reference and educational information only. Not medical advice. Nothing here diagnoses, treats, or prescribes, and nothing here is a recommendation to use any compound. The compounds described are research chemicals and are not approved for human consumption. Legal and anti-doping status change — the review date above is when these claims were last checked. Talk to a qualified clinician about anything you intend to take.