Reviewed & approved by Dr. Nova Reyes · Last checked 2026-10-25. ← Back to Evidence Library

Thymulin: what the evidence says

At a glance

Thymulin has no published treatment trials in people that we found. Unknown

What it is: a 9-amino-acid hormone made by the thymus. It needs zinc to be active, and blood levels fall with age. ^{R1, R2}

What the evidence says: mouse studies only for giving thymulin. Human studies measure the body's own thymulin, for example rising with zinc-fortified milk in very old people. ^{R1, R2}

Biggest risks: unknown in humans. Unknown

Rating


Human Human evidence	No human data: no study gave thymulin to people. The one human study we cite measured the body's own thymulin after zinc-fortified milk ^R1
Animal Animal evidence	Mouse studies ^R2
Regulatory	Not FDA-approved (no Drugs@FDA record) · Not approved as a medicine anywhere in the world · WADA 2026: S0 (unapproved substances) applies ^R3
Established human dose	None. Never tested in people

Evidence verdict: Human: No human data · Animal: mouse studies Card verdict: No human data (immune claims rest on mouse injection studies and human endogenous blood-level studies)

This page reports what studies used. It is not dosing advice.

Legend: HUMAN data · ANIMAL / LAB data · UNKNOWN · UNVERIFIED: not yet confirmed against a primary source

What is it?

Thymulin (once called "facteur thymique sérique") is a zinc-dependent thymic hormone involved in T-cell maturation. ^R1

Does it work?

Animal Mice (2026): thymulin reduced age-related inflammatory immune cells and improved response to cancer immunotherapy in older mice. ^R2
Unknown Zinc, not thymulin (does not count as thymulin evidence): very old people drinking zinc-fortified milk had higher thymulin activity. This tests zinc, not thymulin injections. ^R1
Unknown Anti-aging claims for injected thymulin are vendor or anecdotal claims.

Is it safe?

Unknown No human safety data for injected thymulin.

Gray-market "research use only" Thymulin: extra risks

Unknown contents. Products sold online as "research use only" or "not for human use" are not made under drug-quality rules, so identity, strength and sterility are unknown. This is a general caution; we have not found testing data for this product specifically. Unknown

What we don't know

Unknown Any effect of injected thymulin in people

Is it legal?

Not FDA-approved (no Drugs@FDA record, openFDA query Oct 24, 2026) and not approved as a medicine anywhere in the world. WADA: not named on the 2026 Prohibited List; S0 bans at all times any unapproved substance in development that no other section covers, which describes Thymulin ^R3. WADA has not ruled on Thymulin by name.

Study details

These are doses researchers used, not recommendations.

R1 Human Human: Zinc-fortified milk pilot (Costarelli 2014)

Study	People / model	Route	Dose used	Follow-up	Reported	Side effects / dropouts	Citation
Costarelli 2014	Very old adults, crossover	Oral (zinc milk)	Zinc amounts not in abstract	2 months	Higher thymulin activity	Not in abstract	PMID 24771015

R2 Animal Animal (Kanemaru 2026)

Study	People / model	Route	Dose used	Follow-up	Reported	Side effects / dropouts	Citation
Kanemaru 2026	Aged mice	Injection	See paper	—	Less myeloid inflammation; better tumour control with anti-PD-L1	Not in abstract	PMID 42481458

Full reference list (PubMed entries verified Oct 24, 2026)

^R1 Costarelli L, et al. Age (Dordr). 2014;36(3):9656. PMID 24771015
^R2 Kanemaru H, et al. Nat Commun. 2026;17(1):6534. PMID 42481458
^R3 WADA. World Anti-Doping Code International Standard: Prohibited List 2026 (in force Jan 1, 2026). https://www.wada-ama.org/sites/default/files/2025-09/2026list_en_final_clean_september_2025.pdf (text read Oct 24, 2026)

Disclaimer

This page summarizes published research for education and harm reduction; it is not medical advice or a recommendation to use Thymulin. Talk to a clinician you trust before using any drug, and report side effects to FDA MedWatch.

Approved for Adam Greene by Dr. Nova Reyes, 2026-10-25.