The Ten-Fold Dose Spread
Thymulin
Also known as Zinc-thymulin · FTS · Facteur thymique sérique
At a glance
- What it is
- Zinc-dependent thymic peptide. No established human dose. We publish none.
- Evidence
- Practitioner experience onlyHow the tiers workModern human randomised data on thymulin is essentially absent. Why this tier
- Half-life
- Not established in available literature
- Routes
- Subcutaneous, Topical
- Category
- Immune, Longevity
- WADA
- We do not state a status
- Amino acids
- 9
Not schedulable in Claritide. Our sources publish no dosing figure for Thymulin, so there is nothing to build a schedule from.
Why this tier
Modern human randomised data on thymulin is essentially absent. Most of the clinical literature is from 1980s studies in malnourished populations, and a trial-registry search returns no interventional thymulin trials. The finding worth carrying is the dose spread: one circulating protocol gives 1–5 mg subcutaneously daily in 10–20 day courses with 15–30 mg/day of zinc, another gives 100–400 mcg three times weekly, and a re-check on 17 August 2026 turned up pages quoting 10–20 mcg/day at one end and 1000–5000 mcg/day at the other. Those differ by up to 250 times, which means nobody knows, so we publish no dose at all. We also drop a widely repeated 20-day thymus-priming cycle said to precede an 8-week thymosin alpha-1 and LL-37 phase: single-sourced and self-flagged as unverified.
What it is
Thymulin is a nine-amino-acid peptide from thymic epithelial cells, and the only thymic hormone with a fully characterised chemical structure. It is biologically inactive without zinc. Modern human randomised data is essentially absent, and there is no established human dose: the figures in circulation run from 10 mcg a day to 5 mg a day, a spread of roughly 250 times, with nothing published behind any of them. That is the finding, not a footnote, and it is why this record carries no dosing table.
How it works
Thymulin requires a zinc ion to adopt its active conformation and bind T-cell receptors. Without zinc it is present but inert, which is why it is often written as zinc-thymulin and why community protocols pair it with supplemental zinc. Circulating levels fall with age and are described as near-undetectable by around 60, which is the basis for interest in it as an immune-restoration and longevity compound. The mechanism is reasonably well characterised at the molecular level and almost entirely uncharacterised at the clinical one.
Commonly researched ranges
Not established in available literature. Our sources describe Thymulin without publishing a dosing figure, so Claritide does not print one.
- Cycle guidance
- Community protocols report 10 to 20 day courses two to three times a year. There is no trial behind that schedule, and none behind the amount that would go in it: thymulin’s reported plasma half-life is under 30 minutes, which makes a once-daily protocol pharmacologically odd on its own terms.
- Goals
- Immune, Longevity
Where this sits with the FDA
Thymulin does not appear on any FDA compounding category list as of August 2026. Absence from those lists means no nomination has been assessed either way. It is not a clearance.
Primary sourceWADA status
Not named on the 2026 Prohibited List. We searched for "thymosin" and found only the thymosin-β4 line; thymulin is a different peptide. We could not determine a classification and do not state one.
We looked and could not resolve it. This is not the same as "not prohibited". Treat it as unresolved and check with your federation before competing.
Mixing recipes our sources document
Not established in available literature. Use the calculator with the figures printed on your own vial.
Open the calculator
Week by week
Not established in available literature.
Side effects
Not established in available literature. Absence from this page does not mean absence of risk. It means our sources publish no side-effect profile for Thymulin.
Contraindications and interactions
Do not use if
Not established in available literature.
Interactions
Not established in available literature.
Absence from this list does NOT mean safety. It means lack of research.
Storage and cost
- Storage
- Our sources publish no vial and diluent pairing or beyond-use window for thymulin.
- Cost
- Not established in available literature
Stacks with
Thymulin in full
Limited coverage
Thymulin is a nine-amino-acid peptide from thymic epithelial cells, the only thymic hormone whose chemical structure is fully characterised. It is biologically inactive without zinc: the zinc ion is required for the active conformation and for T-cell receptor binding, which is why it is often written as zinc-thymulin and why community protocols pair it with supplemental zinc.
Circulating levels fall with age and are described as near-undetectable by around 60. That decline is the basis for the interest.
The finding is the dose spread
Two protocols circulate:
- 1 to 5 mg subcutaneously daily, in 10 to 20 day courses, two to three times a year, alongside 15 to 30 mg/day of zinc.
- 100 to 400 mcg three times weekly.
Those differ by roughly a factor of ten, in both amount and frequency. That is not a range; it is two different guesses about what this compound does. A wider sweep in August 2026 stretched it further still, to pages quoting 10 to 20 mcg a day and pages quoting 1000 to 5000 mcg a day.
When the community cannot agree on the dose within an order of magnitude, the honest reading is that nobody knows, and that is the most useful thing this page can tell you. So there is no dosing table on this record and no dose figure to choose anywhere in Claritide. Melanotan II is handled the same way and for the same reason.
The evidence behind either
Essentially nothing modern. The clinical literature is largely 1980s work in malnourished populations, and a trial-registry search returns no interventional thymulin trials. Modern human randomised data is absent.
Thymulin also appears at 0.001% in topical hair formulations alongside GHK-Cu at 1% and PTD-DBM at 0.001%, which is a different product category with its own separate evidence question.
What we drop
A widely repeated protocol places a 20-day thymus-priming cycle of thymulin before an eight-week thymosin alpha-1 and LL-37 phase. It has a single source, and that source flags it as unverified itself. It does not ship.
Sources
Every record in this library is free to read, and it stays free. Your own schedule, vials and log live in the app: Claritide for iPhone.