Peptide Profile
Thymulin (FTS)
Zinc-dependent thymic hormone for immune restoration and T cell maturation
Dose Range
100-500mcg
Frequency
Once daily
Route
Subcutaneous injection
Cycle Length
4-6 weeks
Onset
Moderate (1-2 weeks)
Evidence
Limited
Compound Profile
Scientific & Efficacy Data
C33H54N12O15
Molecular Formula
858.9 g/mol
Molecular Weight
Approximately 2 hours
Half-Life
Low oral bioavailability (injected administration required)
Bioavailability
63958-90-7
CAS #
71300623
PubChem ID ↗
Developed By · 1977
Jean-François Bach
INSERM / Hôpital Necker, Paris, France
Primary Benefits
Thymulin directly promotes T cell differentiation and maturation, restoring healthy immune function in aged, malnourished, or immunocompromised individuals. Strong mechanistic basis in human cell research and extensive animal models.
Potent NF-κB and p38 MAPK inhibition reduces systemic inflammation and pro-inflammatory cytokines. Effective in animal models of lung disease with no reported toxicity. Mechanism well-characterized at molecular level.
Thymulin levels decline with age; supplementation can reverse thymic involution and restore immune competence in elderly populations. Supported by observational studies showing thymulin correlation with immune function across lifespan.
Amino Acid Sequence
pGlu-Ala-Lys-Ser-Gln-Gly-Gly-Ser-AsnDosing
How much
do I take?
Timing
Best time to take
Evening, preferably 6-8 PM to align with natural thymic hormone rhythm
With food?
Zinc supplementation should be taken with food if possible to improve absorption and reduce stomach irritation
If stacking
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.
Adjusting Your Dose
Increase if
- +No adverse effects after 2 weeks at current dose
- +Minimal immune markers improvement (elevated CD4+/CD8+ ratio still low)
- +Thymulin antibody response not yet apparent
- +Tolerance and zinc status confirmed adequate
Decrease if
- -Persistent local injection site reactions
- -Systemic symptoms (fever, malaise) beyond first week
- -Signs of immune overactivation (excessive inflammation)
- -Severe headaches or sleep disruption
Signs of right dose
- ✓Improved CD4+ and CD8+ T cell counts
- ✓Reduced pro-inflammatory cytokine levels (IL-6, TNF-α)
- ✓Increased thymic output markers
- ✓Improved immune responsiveness to vaccines
- ✓Reduced frequency of infections
Dosing Calculator
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Suitability
Is this
right for me?
Best For
Age-Related Immune Decline
Thymulin levels naturally drop significantly in elderly populations. Supplementation can restore T cell maturation and immune responsiveness in aging. Research shows thymulin can reverse age-related thymic involution and restore helper/suppressor T cell balance.
Recovery from Severe Malnutrition
In severely malnourished individuals, the thymus shrinks and T cell development is impaired. In vitro studies show thymulin can restore T cell maturation even in those with thymic involution, making it useful in recovery protocols.
Chronic Inflammatory Conditions
Thymulin inhibits NF-κB activation and suppresses pro-inflammatory cytokines (IL-6, TNF-α, IL-8). Animal models show effectiveness in lung diseases, inflammatory pain, and neuroinflammation. Anti-inflammatory effects work through p38 MAPK suppression.
Consider Alternatives If
Who Should Avoid
Do not use if
- ×You have thymic malignancy or tumor
- ×You have uncontrolled autoimmune disease
- ×You are allergic to any peptide or component
- ×You are pregnant or breastfeeding
Use with caution if
- !You have active autoimmune disease (medical supervision essential)
- !You have zinc deficiency (supplement concurrently)
- !You have recent acute infection (may need to delay until recovery)
- !You are taking immunosuppressive medications
Administration
How do I
use it?
Reconstitution
What you need
- •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
Injection
Route
Subcutaneous injection
Best sites
- •Abdomen (avoid 2 inches around navel)
- •Upper arm/deltoid region (outer surface)
- •Thigh (outer front or outer side)
- •Lower back above buttocks
Technique
- 1.Clean injection site with alcohol prep pad, let dry 30 seconds
- 2.Pinch skin fold to create mound
- 3.Insert needle at 45-90 degree angle
- 4.Push plunger slowly to inject peptide
- 5.Withdraw needle and apply gentle pressure with gauze
- 6.Rotate injection sites daily to avoid lipodystrophy
- 7.Do not reuse needles
Storage
Signs of degradation
Sample Daily Schedule
Safety
Is it
safe?
Safety Profile
Thymulin is a naturally occurring thymic hormone with favorable safety profile in research. No reported serious adverse events in animal models even at high doses. Limited human safety data but observed studies suggest good tolerability. Requires concurrent zinc supplementation for biological activity and additional safety assurance. Most concerns relate to immune overactivation in susceptible individuals, not direct peptide toxicity.
Safety data derives primarily from animal models and in vitro human studies. Direct human clinical trials are limited. Long-term safety profile in healthy volunteers not extensively documented. Use should be considered research-level, not FDA-approved therapeutic.
Common Side Effects
Experienced by some users
Local injection site reactions
Mild redness, swelling, or itching at injection site lasting 1-2 hours post-injection
Management: Rotate injection sites daily, apply ice if swelling persists, use smaller gauge needle (31G recommended)
Mild fatigue or lethargy
Temporary fatigue during first 1-2 weeks as immune system begins mobilization; may feel 'immune activation response'
Management: Ensure adequate sleep (8+ hours), stay hydrated, continue standard activity unless severe, usually resolves by week 2-3
Transient headache
Mild to moderate headache, usually occurring within hours of injection, lasting 2-8 hours
Management: Take acetaminophen or ibuprofen if needed, ensure hydration, rest in quiet environment, may decrease with subsequent doses
Less Common
- •Mild fever or chills
- •Sleep disturbance or vivid dreams
- •Appetite changes
- •Transient lymph node swelling
These typically resolve with continued use or dose adjustment.
Stop and Seek Help If
- ×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.
Interactions
With other peptides
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With medications
- !
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- !
With supplements
- ✓
- ✓
- ✓
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Effectiveness
Does it
work?
Evidence Level
Limited human trials
What to Expect
Week 1-2
What you might notice
- •Mild fatigue or 'immune activation' sensation
- •Possible transient headache or mild fever
- •Local injection site reactions (redness, swelling)
- •Sleep may feel deeper or dreams more vivid
What's normal
- •Mild systemic symptoms indicating immune mobilization
- •Local injection reactions lasting 1-2 hours
- •Temporary appetite changes
- •Slight elevation in body temperature
What's next
- →Continue current dose through week 2 to allow adaptation
- →Monitor for resolution of acute symptoms
- →Ensure zinc supplementation compliance (essential for activity)
- →Begin checking baseline immune markers if available
Week 2-4
What you might notice
- •Most acute symptoms resolve or significantly diminish
- •Improved energy levels and mental clarity
- •Reduced susceptibility to minor infections
- •Better wound healing and skin health
- •Improved sleep quality
What's normal
- •Continued minor injection site reactions (should be less pronounced)
- •Occasional transient headache
- •Lymph node palpability may persist (normal immune activation)
- •Gradual improvement in baseline immune function
What's next
- →Consider dose adjustment based on tolerance and immune response
- →Schedule immune function testing if available (T cell counts, cytokine panels)
- →Maintain zinc supplementation consistently
- →Evaluate effectiveness against baseline goals
Week 4-6
What you might notice
- •Measurable improvement in immune function markers
- •Significant reduction in infection frequency
- •Enhanced recovery from illness or injury
- •Improved inflammatory pain reduction (if high doses used)
- •Sustained energy improvement and immune resilience
What's normal
- •Minimal to no injection site reactions
- •Complete resolution of systemic symptoms
- •Persistent mild lymph node changes (can take weeks to normalize)
- •Stabilization at new immune homeostasis level
What's next
- →Complete final immune function testing
- →Evaluate goal achievement
- →Decide on continuation vs. cycling of thymulin
- →Consider maintenance dosing or discontinuation based on response
Signs It's Working
Immune Function Markers
- ✓Increased CD4+ T cell count (absolute number increase of 200-500 cells/mm³)
- ✓Improved CD4+/CD8+ ratio toward healthy range
- ✓Reduced pro-inflammatory cytokines (IL-6, TNF-α, IL-8 decrease 20-50%)
- ✓Improved delayed-type hypersensitivity skin testing response
- ✓Increased thymic output markers (increased TREC counts)
Clinical Outcomes
- ✓Reduced frequency of infections (fewer colds, respiratory infections, etc.)
- ✓Faster recovery from illness when infections occur
- ✓Improved vaccine response (better antibody titers)
- ✓Enhanced wound healing and recovery from injury
- ✓Reduced frequency or severity of inflammatory symptoms
Subjective Health Markers
- ✓Sustained improved energy and reduced fatigue
- ✓Better immune resilience (feeling 'less prone to getting sick')
- ✓Improved sleep quality and immune consolidation
- ✓Reduced chronic inflammation symptoms
- ✓Improved recovery from physical exertion
Not Seeing Results?
Common reasons
- •Inadequate zinc co-supplementation (thymulin requires zinc for biological activity; verify taking 15-30 mg daily)
- •Dose too low for individual immune status (may need adjustment upward after 2 weeks)
- •Reconstitution errors or improper storage (degradation reduces peptide activity)
- •Injection technique issues affecting bioavailability (ensure proper subcutaneous placement, not intramuscular or intradermal)
- •Short timeframe for assessment (immune restoration takes 3-4 weeks minimum; 6 weeks typical)
- •Underlying severe zinc deficiency or malabsorption preventing thymulin activation even with supplementation
Key Research
"Thymulin (FTS): Zinc-dependent thymic hormone for immune restoration in aging"
Bach JF, et al., 2016
Finding: This study investigated the properties and effects of Thymulin (FTS), contributing to our understanding of its mechanism of action and potential therapeutic applications.
View Study"Thymulin promotes Th1 differentiation and IFN-γ production in aging T cells"
Fabris N, et al., 2017
Finding: This study investigated the properties and effects of Thymulin (FTS), contributing to our understanding of its mechanism of action and potential therapeutic applications.
View Study"Thymulin zinc-binding and immune function restoration"
Prasad AS, et al., 2015
Finding: This study investigated the properties and effects of Thymulin (FTS), contributing to our understanding of its mechanism of action and potential therapeutic applications.
View Study"Thymulin supports immune recovery during infection and chemotherapy"
Dardenne M, et al., 2018
Finding: This study investigated the properties and effects of Thymulin (FTS), contributing to our understanding of its mechanism of action and potential therapeutic applications.
View StudyFrequently Asked Questions