Thymulin
Facteur Thymique Serique / FTS / Serum Thymic Factor / Zinc-FTS
A nonapeptide (9 amino acids) exclusively produced by thymic epithelial cells that requires zinc for biological activity. Thymulin promotes T-cell differentiation, modulates cytokine production, and has analgesic and anti-inflammatory properties. Unlike synthetic thymic peptides, Thymulin's activity is zinc-dependent — it exists in active (zinc-bound) and inactive (zinc-free) forms. Serum levels decline sharply after age 35 as the thymus involutes.
Half-life
~2 hours
Typical Dose
50–100 mcg/day SC
60/100Route
subcutaneous
Category
immune
Evidence Overview
Strength of evidence across clinical, expert, and experimental lanes.
How Thymulin is dosed in practice
Usually taken by subcutaneous (SubQ) injection. Typical range: 50–100 mcg/day SC. Half-life: ~2 hours. Each card gives the dose, frequency and duration from one evidence lane: Clinical (human trials), Expert (practitioner protocols) or Experimental (early or animal data). These ranges describe what has been studied or used; they are not a prescription.
Work out the units to draw with the reconstitution calculator, how long a vial lasts with the vial duration calculator, and how levels fall between doses with the half-life calculator.
Small 1980s trials of synthetic thymulin: in rheumatoid arthritis, 5 mg/day beat placebo on global assessment; in multiple sclerosis, 6 months of SubQ treatment showed no benefit. No human data support 50–100 mcg/day.
- Randomized trials in rheumatoid arthritis (1987)
- Pilot randomized trial in multiple sclerosis (1989)
Used by immunology-focused practitioners for age-related immune decline. The zinc-dependency is clinically important — patients must have adequate zinc levels. Some practitioners prefer Thymulin over Thymalin for its well-characterized mechanism of action.
- Immunology-focused anti-aging practitioners
- Thymic peptide therapy specialty clinics
- Zinc-immunity research integrative protocols
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Upgrade to ProSafety & Contraindications
- Autoimmune diseases (may enhance autoreactive T-cell activity)
- Zinc overload conditions (Wilson's disease)
- Pregnancy or breastfeeding
Thymulin: common questions
What is Thymulin?
A nonapeptide (9 amino acids) exclusively produced by thymic epithelial cells that requires zinc for biological activity. Thymulin promotes T-cell differentiation, modulates cytokine production, and has analgesic and anti-inflammatory properties. Unlike synthetic thymic peptides, Thymulin's activity is zinc-dependent — it exists in active (zinc-bound) and inactive (zinc-free) forms. Serum levels decline sharply after age 35 as the thymus involutes.
How is Thymulin dosed?
Thymulin is usually taken by subcutaneous (SubQ) injection. Typical range in DoseCraft's library: 50–100 mcg/day SC. Clinical (human trials): 1–10 mg/day synthetic thymulin (rheumatoid arthritis trials; 5 mg/day worked best); SubQ in a multiple sclerosis trial; Daily; Up to 6 months. Expert (practitioner protocols): 50–100 mcg/day SC; Once daily for 2–4 week courses; 2–4 weeks, repeated every 3–6 months. These ranges describe what has been studied or used; they are not a prescription.
Is Thymulin FDA-approved?
No. Thymulin is not approved by the FDA for any use in people.
What is the half-life of Thymulin?
DoseCraft's library lists a half-life of ~2 hours. Half-life sets how often a compound is dosed and how long it takes to clear: about five half-lives.
Who should not use Thymulin?
Listed contraindications: Autoimmune diseases (may enhance autoreactive T-cell activity); Zinc overload conditions (Wilson's disease); Pregnancy or breastfeeding.
Information is for educational purposes only. Always consult a licensed healthcare provider before starting any peptide regimen.
Page updated . How we grade evidence: methodology.