Thymopentin (TP-5)
Immune-boosting pentapeptide fragment that enhances T-cell function and dendritic cell maturation
Written by Michael Carroll — Owner, Director of Research · Reviewed by the Peptide Initiative Research Team · Editorial standards
Suggested dose
50 mg
Compound profile
Scientific & efficacy data
Immune
Peptide profile
Moderate human trials
Thymopentin (TP-5)
50 mg · Once daily
Molecular formula
C30H49N9O9
- Mol. weight
- 679.8
- CAS number
- 69558-55-0
- PubChem
- 451417
- Developed · 1979
- Gideon Goldstein
Memorial Sloan-Kettering Cancer Center / Immunobiology Research Institute
Amino acid sequence
Arg-Lys-Asp-Val-Tyr (RKDVY)Immune Enhancement
Directly activates T-cells and dendritic cells to strengthen immune response and resistance to infection
Cardiovascular Support
Improves ejection fraction and exercise capacity while reducing harmful inflammatory cytokines in heart failure patients
Post-Recovery Support
Restores immune function after surgery or major stress by protecting critical immune signaling pathways
Dosing
How much do I take?
50 mg · three times weekly · subcutaneous injection
50 mg
Three times weekly
Covers all 2 documented dose levels · 2 administration routes · timing · dose-adjustment guidance.
Suitability
Is this right for me?
Best for immune system strengthening & recovering from illness or surgery
Best for
Immune System Enhancement
Thymopentin directly increases T-cell function and promotes dendritic cell maturation, making it ideal for people seeking to boost immune response naturally
Cardiac Health Support
Clinical trials show thymopentin improves ejection fraction and exercise capacity in elderly heart failure patients while enhancing immune markers
Post-Surgery Recovery
Helps restore immune function after major surgery and protects important immune responses during recovery period
Consider alternatives if
Do not use if
Use with caution if
Not sure?
Compare Thymopentin (TP-5) with similar peptides to find the best fit for your goals.
Administration
How do I use it?
Subcutaneous injection · Intravenous injection
Route
Subcutaneous (preferred) or Intravenous
Best sites
Covers reconstitution · step-by-step technique · storage · a sample daily schedule.
Safety
Is it safe?
3 common side effects · 3 serious
Thymopentin is well-tolerated with minimal side effects reported in clinical trials.
Most adverse events are mild and local. No serious safety concerns have emerged from decades of clinical use in China and Europe.
Safety profile established through Phase 1-2 clinical trials in cardiac disease, rheumatoid arthritis, HIV, and burns. Dosages up to 100 mg/day IV studied without serious adverse effects.
Common side effects · experienced by some users
Local injection site reaction
Mild redness, swelling, or soreness at injection site lasting a few hours to a day
Management: Rotate injection sites, apply ice if needed, use proper injection technique
Mild fatigue
Temporary tiredness, usually transient as body adjusts to immune stimulation
Management: Rest, ensure adequate sleep, stay hydrated; typically resolves within days
Transient fever
Low-grade fever as immune system responds, usually 99-101°F
Management: Monitor temperature, stay hydrated, fever typically passes within 24 hours
Less common
These typically resolve with continued use or dose adjustment.
Stop and seek help if
- Severe allergic reaction or anaphylaxis
- Persistent high fever above 102°F
- Severe local injection site reaction with spreading infection signs
- Signs of uncontrolled immune activation (severe fatigue, swollen lymph nodes)
- Doctor's recommendation due to new medical condition
Consult healthcare provider before stopping treatment. Do not stop abruptly without medical guidance.
With other peptides
- Caution:
- Caution:
- Caution:
With medications
- Caution:
- Caution:
- Caution:
With supplements
- Safe:
- Safe:
- Safe:
Effectiveness
How do I know it's working?
Moderate human trials · first signs week 1
Evidence level
Moderate human trials
(Phase 1-2)
Regulatory status
Research compound
Onset of effects
Moderate
(1-2 weeks)
How it works
Thymopentin is a tiny 5-amino acid peptide that is the active core of a larger immune protein called thymopoietin.
Think of it like extracting the most powerful part of an immune booster. When you inject it, your immune system's T-cells and dendritic cells wake up and work better. Your body also produces more immune chemicals that fight inflammation and protect health.
It's especially helpful for immune recovery after surgery or stress.
The deeper mechanism
Thymopentin (TP-5) is a pentapeptide (5-amino acid) fragment corresponding to residues 32-36 of thymopoietin (Arg-Lys-Asp-Val-Tyr).
Despite its very short plasma half-life of 30 seconds to minutes, subcutaneous administration provides sustained immunomodulatory effects through multiple mechanisms: (1) T-cell activation and proliferation via increased cGMP signaling; (2) Dendritic cell maturation marked by upregulation of CD40, CD80, CD86, CD83, and MHC Class II; (3) Enhanced IL-12 and TNF-α production by mature dendritic cells; (4) Increased CD4+ T-cell proliferation driven by activated dendritic cells; (5) Modulation of inflammatory cytokines with increased IL-10 (anti-inflammatory) and reduced TNF-α, IL-1β (pro-inflammatory).
These effects make it useful in immune deficiency states, post-surgical recovery, and certain autoimmune conditions. The peptide retains full immunological activity despite being only 5 amino acids due to conformational specificity of the active epitope.
What to expect
Week 1
What you might notice
- Possible mild injection site reaction
- Body adjusting to immune stimulation
- Possible transient mild fatigue
What's normal
- Mild redness at injection site for few hours
- Low-grade temperature elevation
- Slight soreness at injection area
What's next
- Continue with standard dosing
- Rotate injection sites
- Monitor for any persistent reactions
Weeks 2-4
What you might notice
- Improved energy and recovery
- Better sleep quality
- Enhanced sense of well-being
- Faster wound healing if applicable
What's normal
- Occasional mild fatigue as immune system strengthens
- Transient mild fever response
- Continued local site reactions with proper rotation
What's next
- Assess tolerance and effectiveness
- Can increase to 2 mg if desired and well-tolerated
- Continue daily injections as planned
Weeks 5-6
What you might notice
- Noticeable improvement in immune markers if tested
- Better resistance to minor infections
- Sustained energy improvements
- Enhanced athletic recovery
What's normal
- Minimal side effects by week 5-6
- Consistent injection site responses
- Body fully adapted to peptide
What's next
- Complete the 4-6 week cycle as planned
- Consider 2-4 week break before next cycle
- Retest immune markers if desired
Signs it's working
Immune markers
- Increased CD3+ and CD4+ T-cell counts
- Enhanced white blood cell function
- Improved response to vaccines
- Better immune memory formation
Physical improvements
- Faster recovery from workouts
- Quicker wound healing
- Improved energy levels
- Better sleep quality
- Reduced susceptibility to colds
Not seeing results? Common reasons
- Improper injection technique - ensure you're using correct angle and depth
- Not rotating injection sites - varies location daily to prevent tissue damage
- Reconstituted peptide degraded - check for cloudiness, discoloration, or age
- Expecting too-rapid results - immune changes take 1-2 weeks minimum
- Combining with immunosuppressants - these reduce effectiveness significantly
- Inadequate dosing or inconsistent schedule - maintain daily routine for best results
Key research
Clinical trials
Tested in people
10 registered studies, 1 still enrolling.
By phase
A trial spanning two phases is counted in both, so these can sum above the total. Observational studies carry no phase.
What kind of research
About 333 people took part in the studies that actually administered Thymopentin (TP-5). Observational studies analyse the records of people already taking it — nobody was given anything for the study, so they are counted separately and cannot show cause and effect.
Most recent
Phase1 First in Human Ascending Dose Study to Evaluate the Safety and Tolerability of FC-12738 in Health Adults
Neurodegenerative Disease Research Inc
The Prospective Clinical Study of Precision PRaG Therapy in Elderly Patients With Advanced Solid Malignant Tumors (PRaG9.0)
Second Affiliated Hospital of Soochow University
Study of Thymopentin in Patients After Curative Resection of Small Hepatocellular Carcinoma
Fudan University
Sources: ClinicalTrials.gov, the EU Clinical Trials Information System and ISRCTN, deduplicated so a study registered twice is counted once. A study is counted when Thymopentin (TP-5) is named as an intervention; studies that only mention it in passing are not.
Questions
Frequently asked
What exactly is Thymopentin and where does it come from?
Thymopentin (TP-5) is a pentapeptide (5-amino acid chain) that was discovered in 1979 by Gideon Goldstein at Memorial Sloan-Kettering Cancer Center. It's the active core fragment of thymopoietin, a naturally occurring hormone that helps regulate immune function. The sequence is RKDVY (Arg-Lys-Asp-Val-Tyr), and despite being tiny, it contains all the immune-stimulating power of the larger parent protein.
Is Thymopentin FDA approved in the United States?
No, Thymopentin is not FDA approved in the United States. However, it has been approved and used clinically in China, Italy, and several other countries for decades. It has strong clinical data in cardiac disease, autoimmune conditions, and immune support. Always consult your healthcare provider about its use and legality in your jurisdiction.
How quickly does Thymopentin work?
You may notice initial effects within 1-2 weeks, such as improved energy and better sleep. However, significant immune marker improvements typically take 4-6 weeks of consistent daily use. Individual responses vary; some people notice changes within days while others need the full cycle to feel benefits.
Why is the half-life so short if it's effective?
Excellent question. While Thymopentin has a plasma half-life of only 30 seconds to a few minutes (it's quickly broken down by enzymes), when injected subcutaneously, it creates a depot effect that provides sustained release. Additionally, its effects on immune cells (T-cells and dendritic cells) trigger longer-lasting signaling cascades that continue long after the peptide itself is gone. So the peptide itself is brief, but its immune effects persist.
What are the most common side effects?
Most users experience minimal side effects. The most common are mild local reactions at the injection site (redness or soreness) and transient fatigue or low-grade fever in the first week as your immune system activates. These typically resolve quickly and are normal signs that the peptide is working. Serious side effects are extremely rare.
Can I combine Thymopentin with other immune peptides?
Yes, many people combine it with other immune-supporting peptides like Thymosin alpha-1 or with supplements like Vitamin D and Zinc. However, always allow 2 hours between different peptide injections, and consult your healthcare provider, especially if you're using immunosuppressive medications.
How do I know if my Thymopentin is still good after reconstitution?
A reconstituted solution should be clear and colorless. Do not use if the solution is cloudy, discolored (yellowing), has visible particles, or has an unusual odor. Once reconstituted, use within 24-48 hours when stored in the refrigerator. Always store in a sterile vial.
What's the difference between subcutaneous and intravenous injection?
Subcutaneous injections (under the skin) are easier to do at home and provide sustained release due to the depot effect. Intravenous (IV) injections go directly into the bloodstream and provide immediate effect but much shorter duration. Most people use subcutaneous for convenience and better sustained results.
Further reading
History & related research
History · since 1975
A synthetic pentapeptide immunomodulator derived from thymopoietin that contains just five amino acids but retains all the immune-boosting power of the full 49-amino-acid hormone.
A synthetic pentapeptide immunomodulator derived from thymopoietin that contains just five amino acids but retains all the immune-boosting power of the full 49-amino-acid hormone. From HIV treatment to heart failure and cancer immunotherapy, these five letters changed medicine.
Read the full history of Thymopentin (TP-5)Ready for the protocol?
Every dosing tier, administration route, timing note, and dose-adjustment rule for Thymopentin (TP-5), on one page.