Thymalin vs Thymulin (FTS)
Russian thymic peptide complex that rejuvenates immune function and supports healthy aging
Zinc-dependent thymic hormone for immune restoration and T cell maturation
Quick comparison
Dose range
Thymalin
5–10 mg
Thymulin (FTS)
1–2 mg
Frequency
Thymalin
Once daily
Thymulin (FTS)
Once daily
Administration
Thymalin
Intramuscular injection
Thymulin (FTS)
Subcutaneous injection
Cycle length
Thymalin
4-6 weeks
Thymulin (FTS)
4-6 weeks
Onset speed
Thymalin
Moderate (1-2 weeks)
Thymulin (FTS)
Moderate (1-2 weeks)
Evidence level
Thymalin
Limited human trials
Thymulin (FTS)
Limited human trials
Benefit ratings
Immune Restoration
Longevity Support
Disease Prevention
Anti-Inflammatory
Age-Related Immune Decline
Compound specifications
Thymalin
Molecular formula
Complex mixture; active dipeptide EW: C16H19N3O5
Molecular weight
Polypeptide complex; components 250-1000 Da; active dipeptide EW ~321 Da
Half-life
Not precisely characterized for complex; immune effects persist weeks post-administration
Bioavailability
High via intramuscular or subcutaneous injection
CAS number
63958-90-7
Thymulin (FTS)
Molecular formula
C33H54N12O15
Molecular weight
858.9 g/mol
Half-life
Approximately 2 hours
Bioavailability
Low oral bioavailability (injected administration required)
CAS number
63958-90-7
Dosing compared
Thymalin
Intramuscular injection
5-10 mg reconstituted in saline
Once daily · 5-10 day course, often repeated every 6 months
Reflects the Russian clinical course used in immune-restoration and gerontology protocols, typically 10 mg IM daily for 5-10 days [1].
Subcutaneous injection
10 mg
Once daily · Up to 20 day course, repeated every 6 months
Subcutaneous administration is used in community practice at the same 10 mg daily dosing; longer 20-day courses are described for cyclical immune support [1].
Thymulin (FTS)
Subcutaneous injection
1-2 mg
Once daily (often dosed in the evening) · 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].
Intradermal injection
100-400 mcg
Three times weekly · Several weeks
Lower microgram-range intradermal dosing is used in some research protocols as a conservative entry point [1].
Best suited for
Thymalin
Aging Adults Seeking Immune Support
Thymalin is especially valuable for people over 55 whose thymus gland has naturally shrunk with age. By stimulating thymic function, it helps restore the immune training center that your body relies on to fight infections and stay healthy.
Longevity and Anti-Aging Protocols
Clinical studies tracking patients for 6-8 years showed Thymalin reduced mortality by 2.0-2.1-fold. Combined with Epitalon, the mortality reduction reached an impressive 4.1-fold, making this combination one of the most studied longevity peptide protocols.
Seasonal Illness Prevention
Research shows Thymalin cuts respiratory infection rates by 2.0-2.4-fold. A short 10-day course before cold and flu season can significantly boost your immune defenses for months afterward.
Thymulin (FTS)
Age-Related Immune Decline
Thymulin levels naturally drop significantly in elderly populations. [9][10] Supplementation can restore T cell maturation and immune responsiveness in aging. [23] Research shows thymulin can reverse age-related thymic involution and restore helper/suppressor T cell balance. [7][11]
Recovery from Severe Malnutrition
In severely malnourished individuals, the thymus shrinks and T cell development is impaired. [24] In vitro studies show thymulin can restore T cell maturation even in those with thymic involution, [13] 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). [14][16] Animal models show effectiveness in lung diseases, inflammatory pain, and neuroinflammation. [14][15][17] Anti-inflammatory effects work through p38 MAPK suppression. [15]
Side effects
Thymalin
Common
- No side effects in most patients
- Mild injection site reaction
Uncommon
- Transient low-grade fever
- Mild flu-like symptoms
- Temporary headache
Serious
- Severe allergic reaction
Thymulin (FTS)
Common
- Local injection site reactions
- Mild fatigue or lethargy
- Transient headache
Uncommon
- Mild fever or chills
- Sleep disturbance or vivid dreams
- Appetite changes
- Transient lymph node swelling
Serious
- Severe allergic reaction
- Uncontrolled immune activation
Safety & evidence
Thymalin
Evidence level
Limited human trials
FDA status
Research compound
Safety overview
Thymalin has an excellent safety profile based on over 40 years of clinical use in Russia. Most patients experience zero side effects, and the peptide complex has been described as 'practically non-toxic' in research literature. It has been used safely in thousands of patients, including elderly populations over extended periods.
Contraindications
- Active thymic tumors or malignancies
- Known hypersensitivity to animal-derived peptide products
- Pregnancy and breastfeeding (insufficient safety data)
- Severe uncontrolled autoimmune disease without medical supervision
Thymulin (FTS)
Evidence level
Limited human trials
FDA status
Research compound
Safety overview
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. [8][14] Limited human safety data but observed studies suggest good tolerability. Requires concurrent zinc supplementation for biological activity [6][7] and additional safety assurance. Most concerns relate to immune overactivation in susceptible individuals, not direct peptide toxicity.
Contraindications
- Uncontrolled autoimmune disease
- Severe zinc deficiency requiring IV repletion
- Thymic tumors or malignancies
- Pregnancy (limited safety data)
Which is right for you?
Choose Thymalin if...
- Immune system restoration in aging adults
- Longevity and healthy aging support
- Reducing infection frequency and severity
- Multi-system health optimization
Choose Thymulin (FTS) if...
- Immune system restoration
- T cell maturation in immunocompromised states
- Age-related immune decline
- Chronic inflammatory conditions