Pidotimod vs Thymalin
Synthetic dipeptide immunomodulator that enhances both innate and adaptive immunity through Toll-like receptor activation
Russian thymic peptide complex that rejuvenates immune function and supports healthy aging
Written by Michael Carroll — Owner, Director of Research · Reviewed by the Peptide Initiative Research Team · Editorial standards
Quick comparison
Dose range
Pidotimod
800–800 mg
Thymalin
5–10 mg
Frequency
Pidotimod
Multiple times daily
Thymalin
Once daily
Administration
Pidotimod
Oral (tablet)
Thymalin
Intramuscular injection
Cycle length
Pidotimod
12+ weeks
Thymalin
4-6 weeks
Onset speed
Pidotimod
Moderate (1-2 weeks)
Thymalin
Moderate (1-2 weeks)
Evidence level
Pidotimod
Moderate human trials (Phase 1-2)
Thymalin
Limited human trials
Benefit ratings
Immune
Healing & Recovery
Anti-Aging
Immune Restoration
Longevity Support
Disease Prevention
Compound specifications
Pidotimod
Molecular formula
C9H12N2O4S
Molecular weight
244.27 g/mol
Half-life
Approximately 4 hours
Bioavailability
~45% (oral)
CAS number
121808-62-6
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
Dosing compared
Pidotimod
Oral
400 mg (pediatric, age >3 yr): twice daily for acute infection, once daily for prevention
Twice daily (acute) or once daily (prevention) · 15-20 days acute; up to 60 days for prevention
Approved pediatric dosing (Italy/Asia; not FDA-approved). Take 2 hours before or after food to preserve absorption. [2][6]
800 mg (adults): twice daily for acute infection, once daily for prevention
Twice daily (acute) or once daily (prevention/maintenance) · 8-15 days acute; up to ~60 days for prophylaxis
Standard adult dosing for acute respiratory infection with antibiotics, then once-daily maintenance. Take away from meals. [5][6]
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].
Best suited for
Pidotimod
Recurrent Respiratory Infections
Pidotimod is specifically indicated and most widely studied for preventing recurrent respiratory tract infections (RRTIs), particularly in children over 3 years. Multiple clinical studies and a Phase 4 trial with 338 children have demonstrated significant reductions in infection frequency and duration.
Immunocompromised Patients
Patients with documented cell-mediated immunodepression, including those with HIV or the elderly with weakened immune function, may benefit from pidotimod's ability to enhance T-cell function and rebalance cytokine production.
Seasonal Immune Support
Preventive courses before cold and flu season can strengthen immune defenses through TLR activation and enhanced mucosal immunity (increased salivary IgA), reducing susceptibility to viral respiratory infections.
Chronic Respiratory Conditions
Patients with chronic bronchitis, bronchiectasis, or COPD who experience frequent exacerbations may benefit from pidotimod as an adjunctive therapy to reduce infection-triggered flares.
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.
Side effects
Pidotimod
Common
- Gastrointestinal discomfort
- Skin rash
- Headache
- Nausea
- Diarrhea
- Transient fever
Uncommon
- Allergic reaction
Serious
- Severe hypersensitivity reaction
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
Safety & evidence
Pidotimod
Evidence level
Moderate human trials (Phase 1-2)
FDA status
Research compound
Safety overview
Pidotimod (immuno-stimulating dipeptide analog) has 40+ years of safety data in European/Asian markets with favorable tolerability profile. Mild gastrointestinal effects occur in <5% of users; no serious adverse events in 25 years of clinical use across 50,000+ patient population. Oral bioavailability excellent with rapid intestinal absorption. No mutagenicity or carcinogenicity in preclinical testing; immunomodulatory mechanism carries theoretical risk in severely immunocompromised patients.
Contraindications
- Known hypersensitivity to pidotimod or any excipients
- Pregnancy and breastfeeding (insufficient safety data)
- Children under 3 years of age
- Severe autoimmune disease in active flare
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
Which is right for you?
Choose Pidotimod if...
- Preventing recurrent respiratory tract infections
- Supporting immune function in immunocompromised individuals
- Reducing frequency of infections in children and elderly
- Immune support during HIV management
Choose Thymalin if...
- Immune system restoration in aging adults
- Longevity and healthy aging support
- Reducing infection frequency and severity
- Multi-system health optimization