Zinc-dependent thymic hormone for immune restoration and T cell maturation
Written by Michael Carroll — Owner, Director of Research · Reviewed by the Peptide Initiative Research Team · Editorial standards
Subcutaneous
Route
4 recommended
Sites
Once daily
Frequency
Preparation
Sterile bacteriostatic water (0.9% sodium chloride) or sterile saline
Insulin syringe (29-31 gauge, 0.5-1 mL)
Alcohol prep pads
Sterile gauze
Sharps container
Sealed vial with lyophilized thymulin
Pro tip
Prepare all supplies on a clean surface before you begin. Having everything ready makes the process smoother and more sterile.
Mixing
Wash your hands thoroughly with soap and water. Gather all supplies on a clean, flat surface.
Remove the plastic cap from the peptide vial and wipe the rubber stopper with an alcohol swab. Let it air dry.
Draw the appropriate amount of bacteriostatic water into a sterile syringe.
Insert the needle into the vial at an angle, aiming at the inside wall of the vial. Slowly push the plunger to let the water trickle down the glass wall -- do NOT squirt directly onto the powder.
Once all water is added, gently swirl the vial in a slow circular motion. Never shake the vial, as this can damage the peptide bonds.
Continue swirling until the powder is completely dissolved and the solution is clear. If particles remain, let the vial sit for a few minutes and swirl again.
Label the vial with the date of reconstitution, the peptide name, and the concentration (e.g. 250mcg per 0.1mL).
Example calculation
If vial contains 1 mg (1000 mcg) thymulin: To achieve 250 mcg per injection, reconstitute with 4 mL bacteriostatic water, then draw 1 mL for 250 mcg dose.
Dose calculation
Total mcg in vial ÷ Total mL reconstituted = mcg per mL. Then (Desired dose in mcg ÷ mcg per mL) = mL to draw.
Pro tip
Always add the bacteriostatic water slowly, letting it run down the side of the vial. Never shake the vial -- swirl gently to avoid damaging the peptide.
Location
Site 01
Abdomen
Pinch the skin 2 inches from navel. Avoid the area directly around the belly button. Rotate between left and right sides.
Site 02
Upper Arm
Back or outer area of the upper arm. This site may require assistance from another person for proper technique.
Site 03
Outer Thigh
Middle third of the outer thigh. Keep at least 4 inches above the knee and below the hip. Alternate legs each injection.
Site 04
Gluteal
Upper outer quadrant of the buttock. This site is best for intramuscular injections and larger volumes.
Rotate between 4 sites to prevent tissue buildup and ensure consistent absorption.
Pro tip
Rotate your injection sites with each dose to prevent lipohypertrophy (buildup of fatty tissue). Keep a simple log of where you last injected.
Step by step
Clean injection site with alcohol prep pad, let dry 30 seconds
Pinch skin fold to create mound
Insert needle at 45-90 degree angle
Push plunger slowly to inject peptide
Withdraw needle and apply gentle pressure with gauze
Rotate injection sites daily to avoid lipodystrophy
Do not reuse needles
Pro tip
This peptide uses subcutaneous injection. Inject at a 45-90 degree angle into pinched skin. Aspirate before injecting to ensure you haven't hit a blood vessel.
Timing
Optimal timing
Best time
Evening, preferably 6-8 PM to align with natural thymic hormone rhythm [20]
With food?
Zinc supplementation should be taken with food if possible to improve absorption and reduce stomach irritation
Stacking notes
Separate thymulin injection from zinc supplement by at least 2 hours if supplementing with separate zinc dose. Can combine in reconstitution if using zinc-supplemented formulation.
Sample daily schedule
Evening (6-8 PM)
Starting: 100 mcg; Standard: 250-300 mcg; Advanced: 500 mcg injection
Site: Rotate between abdomen, outer thigh, upper arm, and lower back
Inject subcutaneously at same time daily. Evening timing aligns with natural thymic hormone circadian rhythm. Always use fresh, sterile needle.
Dosing tiers
Dose
1-2 mg
Frequency
Once daily (often dosed in the evening)
Duration
10-20 day courses, repeated cyclically
Research-practice dosing for immune support; thymulin requires injectable delivery due to low oral bioavailability and a zinc ion for activity, so zinc co-supplementation is commonly paired [1].
Dose
100-400 mcg
Frequency
Three times weekly
Duration
Several weeks
Lower microgram-range intradermal dosing is used in some research protocols as a conservative entry point [1].
Preservation
Before mixing
Store lyophilized powder at 2-8°C (preferred) or 18-25°C in original sealed vial, protected from light and moisture. Do not freeze.
After mixing
Store reconstituted solution at 2-8°C in sterile vial or syringe. Keep sealed to prevent contamination. Use within 5-7 days.
Shelf life after mixing
5-7 days when stored at 2-8°C
Signs of degradation
Discard the vial immediately if you notice any of these:
Cloudiness or particles in solution
Color change (discoloration or darkening)
Unusual odor
Solution appears separating or layered
Important
When to stop
Severe allergic reactions or anaphylaxis
Persistent fever above 101.5°F lasting more than 24 hours
Severe joint or muscle pain unrelated to injection site
Signs of autoimmune activation (rashes, persistent inflammation)
Severe headaches or neurological symptoms
Uncontrolled immune activation with systemic symptoms
Pregnant status or planning pregnancy
Development of new autoimmune disease symptoms
This information is for research purposes only. Stopping thymulin or any peptide should be discussed with a qualified healthcare provider. Do not discontinue abruptly without medical guidance. If experiencing emergency symptoms, seek immediate medical attention.
Clean technique checklist
Wash hands thoroughly with soap and water before handling supplies
Swab vial tops and injection site with alcohol and let dry
Never touch the needle tip or allow it to contact non-sterile surfaces
Use a new syringe and needle for each injection
Dispose of used sharps in a proper sharps container
Store reconstituted peptides according to the storage instructions above
Published research
Bach JF, et al. · 2014
This study investigated the properties and effects of Thymulin (FTS), contributing to our understanding of its mechanism of action and potential therapeutic applications.
Fabris N, et al. · 2017
This study investigated the properties and effects of Thymulin (FTS), contributing to our understanding of its mechanism of action and potential therapeutic applications.
Bach JF, Dardenne M · 1989
This study investigated the properties and effects of Thymulin (FTS), contributing to our understanding of its mechanism of action and potential therapeutic applications.
Safieh-Garabedian B, Kendall MD, Khamashta MA, et al. · 1992
This study investigated the properties and effects of Thymulin (FTS), contributing to our understanding of its mechanism of action and potential therapeutic applications.
Bach JF, Dardenne M, Pleau JM, Rosa J · 1977
Original biochemical characterisation of the serum thymic factor (FTS) isolated from pig serum, establishing it as a small thymus-derived peptide hormone acting on T lymphocytes.
Dardenne M, Pleau JM, Lefrancier P, Bach JF · 1981
FTS loses its biological activity after passage over a chelating agent and recovers it on addition of zinc; activation is secondary to zinc binding to the peptide. Two forms exist - one zinc-free and biologically inactive, one zinc-bound and biologically active, for which the name thymulin was proposed.
Bach JF, Dardenne M · 1989
Thymulin is a nonapeptide hormone produced by thymic epithelial cells whose biological activity and antigenicity depend on the presence of zinc in the molecule. It induces differentiation of T cells and enhances several functions of the various T-cell subsets, with the effect on suppressor T cells the most remarkable. The peptide is not toxic.
Reggiani PC, Morel GR, Console GM, Barbeito CG, Rodriguez SS, Brown OA, Bellini MJ, Pleau JM, Dardenne M, Goya RG · 2009
Review. Thymulin is produced exclusively by thymic epithelial cells and consists of a nonapeptide component coupled in equimolecular ratio to the ion zinc, which confers biological activity and a specific molecular conformation on the molecule; it is involved in intrathymic and extrathymic T cell differentiation, possesses anti-inflammatory and analgesic properties in the brain, and has no known toxic effects even at high doses.
Lewis VM, Twomey JJ, Bealmear P, Goldstein G, Good RA · 1978
Circulating thymic hormone activity in humans was highest at 15-30 years of age and declined thereafter, being negligible after the sixth decade; the age-related decline correlated in general with progressive thymic involution.
Consolini R, Legitimo A, Calleri A, Milani M · 2000
Plasma thymulin measured in 93 healthy individuals from birth to old age: detectable at birth, highest at 5-10 years, falling gradually from adolescence to its lowest value at age 36 and remaining low through age 80. Thymulin is described as a nonapeptide secreted by the thymus and essential for T lymphocyte differentiation and function.
Mocchegiani E, Santarelli L, Muzzioli M, Fabris N · 1995
In deep zinc deficiency low thymulin levels are due not to a primary failure of the thymus but to reduced peripheral saturation of the hormone by zinc ions; in aged mice both reduced zinc saturation and decreased thymic production were present. One month of oral zinc supplementation in 22-month-old mice produced full recovery of thymic function with regrowth of the organ and partial restoration of peripheral immune efficiency, indicating that age-related thymic involution is not an intrinsic, irreversible event.
Prasad AS, Meftah S, Abdallah J, Kaplan J, Brewer GJ, Bach JF, Dardenne M · 1988
Serum thymulin activity fell in three human models of mild zinc deficiency and was corrected by in vivo and in vitro zinc supplementation. Zinc depletion also decreased the T4+/T8+ ratio and IL-2 activity, both corrected after zinc repletion. Thymulin activity depends on the presence of zinc in the molecule and thymulin induces intra- and extrathymic T cell differentiation.
Parent G, Chevalier P, Zalles L, Sevilla R, Bustos M, Dhenin JM, Jambon B · 1994
Bolivian children hospitalised for severe protein-energy malnutrition showed a high degree of T lymphocyte immaturity correlating with severe involution of the thymus; after in vitro incubation with thymulin, immature T lymphocytes decreased and mature T lymphocytes increased.
Santos M, Henriques-Coelho T, Leite-Moreira A · 2010
Review. Thymulin has consistent beneficial effects in experimental models of lung disease, a broad inhibitory effect on pro-inflammatory cytokines, suppresses p38 (a MAPK family member) and inhibits activation of the NF-kappaB signalling pathway, and has no toxicity even at high doses.
Nasseri B, Zaringhalam J, Daniali S, Manaheji H, Abbasnejad Z, Nazemian V · 2019
In a complete Freund's adjuvant rat model, intraperitoneal thymulin reduced thermal hyperalgesia and paw edema, reduced activation of spinal microglia, reduced phosphorylation of p38 MAPK, and reduced spinal production of the pro-inflammatory cytokines TNF-alpha and IL-6.
Novoselova EG, Lunin SM, Glushkova OV, Khrenov MO, Parfenyuk SB, Zakharova NM, Fesenko EE · 2018
In mice given escalating doses of lipopolysaccharide, thymulin treatment alleviated fever, reduced lymphocyte apoptosis, decreased plasma pro-inflammatory cytokine production and decreased the activity of the NF-kappaB, MAPK and PKC-theta signalling pathways together with Hsp72, Hsp90 and TLR4 expression.
Safieh-Garabedian B, Jabbur SJ, Dardenne M, Saade NE · 2011
In a rat model of neuroinflammation produced by intracerebroventricular endotoxin, pretreatment with the thymulin analogue PAT significantly alleviated endotoxin-induced hyperalgesia and the elevated concentrations of pro-inflammatory mediators measured across brain regions.
Dardenne M, Saade N, Safieh-Garabedian B · 2006
Review of thymulin and its synthetic analogue PAT. PAT is deprived of thymulin's hyperalgesic effect; compared with other anti-inflammatory drugs PAT exerted equal or even stronger analgesic effects, and at much lower concentrations. Thymulin injected intracerebroventricularly reduced endotoxin-induced hyperalgesia and inhibited nuclear activation of NF-kappaB in the hippocampus, suggesting a neuroprotective role in the CNS.
Safieh-Garabedian B, Dardenne M, Pleau JM, Saade NE · 2002
PAT (peptide analogue of thymulin) dose-dependently reduced endotoxin-induced mechanical and thermal hyperalgesia in rats, reduced raised IL-1beta, IL-6, TNF-alpha and NGF, prevented endotoxin-induced fever, and at all doses used produced no evident change in physiological parameters or normal behaviour.
Molinero P, Soutto M, Benot S, Hmadcha A, Guerrero JM · 2000
Serum thymulin concentrations showed a 24-hour rhythm with values increasing at night, in rats and in humans; daytime melatonin injection raised thymulin, while continuous light exposure and pinealectomy lowered it.
U.S. National Library of Medicine, ClinicalTrials.gov · 2026
A search of the ClinicalTrials.gov registry for thymulin as a study intervention returns no registered studies; a whole-record term search for thymulin returns only a zinc supplementation trial in which thymulin is not the intervention (checked 16 September 2026).
Prasad AS · 2008
Review. In an experimental human model of zinc deficiency, severe immune dysfunction mainly affecting T helper cells and decreased serum thymulin activity were documented; dietary zinc deficiency arose in populations eating mainly high-phytate cereal protein, and decreased plasma zinc in elderly subjects was corrected by zinc supplementation.
Muzzioli M, Mocchegiani E, Bressani N, Bevilacqua P, Fabris N · 1992
Thymulin (Zn-FTS), whose production and activity is generally reduced in old age, restored in vitro the crippled natural killer cytotoxicity of spleen cells from old mice; neither the zinc-unbound form of the hormone nor zinc ions alone were effective.
Jambon B, Ziegler O, Maire B, Hutin MF, Parent G, Fall M, Burnel D, Duheille J · 1988
In 58 Senegalese children who died in various stages of malnutrition, the severe forms (marasmus, kwashiorkor, marasmic kwashiorkor) showed a tiny thymus containing very little thymulin; thymic atrophy and depleted thymulin content were associated with severe protein-energy malnutrition.
U.S. Food and Drug Administration · 2026
Drugs@FDA and the openFDA drug label and drugsfda endpoints return no approved application and no labeling for thymulin; there is no FDA-approved thymulin product in the United States (checked 16 September 2026).
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