Thymosin Alpha-1, also called thymalfasin, Zadaxin, or Ta1, is a thymic peptide studied as an immune modulator in sepsis, severe pancreatitis, chronic hepatitis B, and cancer-treatment settings. Its evidence grade is A by quantity and design, but that grade does not prove benefit, safety, or suitability for any person.
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See if you qualify →What it is
Thymosin Alpha-1 is a thymic peptide, meaning it is related to peptides first identified in the thymus, an immune-system organ. It is also known as thymalfasin, Zadaxin, and Ta1.
In the retrieved human literature, Thymosin Alpha-1 appears most often as an immune modulator studied in serious illness settings, including sepsis, shock, severe acute pancreatitis, chronic hepatitis B, and cancer-treatment combinations 1 2 4 5 8. That is different from saying it has proven value for everyday wellness or longevity.
Names: thymalfasin, Zadaxin, and Ta1
You may see the same substance described as Thymosin Alpha-1, thymosin α1, thymalfasin, Zadaxin, or Ta1. In the studies retrieved for this page, both “thymosin alpha-1” and “thymalfasin” are used in human clinical settings 6 8.
What this page covers and what it does not
This page covers human clinical evidence, reported study contexts, safety limits, interactions, and safer access questions. If you want a broader patient-friendly overview, our related guide on Thymosin Alpha-1 as an immune peptide explains the same topic in a less technical format.
It does not give personal dosing advice. It also does not treat immune-marker changes as proof of better health outcomes.
Mechanism of action
Thymosin Alpha-1 is usually discussed as an immune-modulating peptide. In the retrieved human studies, the clearest mechanism-related language is about immune enhancement and cellular immunity, including severe acute pancreatitis studies that measured immune-related outcomes 2 3.
Cellular immunity includes immune responses driven by cells such as T cells. But the supplied human records do not establish a single receptor pathway that explains all possible effects in people, so any detailed pathway claim should be treated as proposed rather than proven.
Immune modulation and T-cell signaling
In plain English, immune modulation means “changing immune activity,” not simply turning it up or down. A double-blind randomized study in severe acute pancreatitis reported that Thymosin Alpha-1 was associated with improved cellular immunity and reduced infection rate in that study population 3.
That finding is specific to a serious inpatient condition. It should not be stretched into a claim that Ta1 improves immunity in healthy adults.
Why mechanism data should not be read as proof of clinical benefit
A mechanism can be real and still not lead to a meaningful patient outcome. For example, sepsis, pancreatitis, hepatitis B, and cancer-treatment trials all involve different immune problems and different background treatments 1 2 5 7.
This is why we separate “how it may work” from “what human studies actually showed.” At Chia, we use this same evidence-first approach when we explain peptide injections and other peptide therapies to patients.
Evidence
Thymosin Alpha-1 has an evidence grade of A under the rubric used for this page because the retrieved evidence set includes multiple human randomized controlled trials 1 2 3 5 6.
The grade is about the amount and design of published research. It is not a stamp of effectiveness, safety, approval, access, or personal fit.
Sepsis and shock studies
A multicenter, double-blind, randomized, placebo-controlled phase 3 trial studied Thymosin α1 for sepsis in the TESTS trial 1. Another randomized study evaluated Thymosin α1 combined with blood purification in shock patients 4.
These are serious hospital settings. They do not show that Thymosin Alpha-1 is useful for general “immune support” in otherwise healthy people.
Severe acute pancreatitis studies
A multicenter, double-blind randomized controlled trial studied immune enhancement in patients with predicted severe acute necrotising pancreatitis 2. An earlier double-blind randomized controlled study in severe acute pancreatitis reported improved cellular immunity and reduced infection rate in that specific patient group 3.
These studies support pancreatitis as a real human research area for Ta1. They do not prove benefit for recovery from exercise, routine inflammation, or longevity.
Chronic hepatitis B studies
Randomized controlled trials have studied Thymosin Alpha-1 in chronic hepatitis B, including anti-HBe, HBV-DNA-positive chronic hepatitis B and HBeAg-negative chronic hepatitis B compared with interferon-alpha 5 6.
Hepatitis B studies are disease-specific. They should not be used to claim broad antiviral protection.
Cancer-treatment combination studies
Thymosin Alpha-1 has also been studied inside combination cancer-treatment regimens. One multicenter phase 2 trial combined hypofractionated radiotherapy, a PD-1 inhibitor, granulocyte macrophage-colony stimulating factor, and thymosin-α1 in advanced metastatic solid tumors 7. A prospective clinical trial studied neoadjuvant immunochemotherapy plus thymalfasin in locally advanced gastric cancer 8.
These studies do not isolate Ta1 as a stand-alone cancer treatment. They test complex combinations in oncology care.
| Research area | Human evidence in retrieved set | What can be said | What should not be assumed |
|---|---|---|---|
| Sepsis | Multicenter, double-blind, randomized, placebo-controlled phase 3 trial | Sepsis is a major human research area for Thymosin Alpha-1 1. | Do not assume benefit for general immune support. |
| Shock | Randomized study with blood purification | Ta1 has been studied as part of a shock-care combination 4. | Do not assume the peptide alone caused any outcome. |
| Severe acute pancreatitis | Multicenter RCT and earlier double-blind RCT | Studies evaluated immune enhancement, cellular immunity, and infection outcomes 2 3. | Do not apply these findings to routine recovery or wellness. |
| Chronic hepatitis B | Randomized controlled trials | Trials studied anti-HBe, HBV-DNA-positive and HBeAg-negative chronic hepatitis B 5 6. | Do not assume broad antiviral benefit. |
| Cancer-treatment combinations | Phase 2 and prospective clinical trials | Ta1 has been studied with immunotherapy, radiotherapy, chemotherapy, or other immune-active agents 7 8. | Do not treat this as stand-alone cancer evidence. |
What studies exist
| Year | Design | Study | Journal | Record |
|---|---|---|---|---|
| 2025 | Randomised controlled trial | The efficacy and safety of thymosin α1 for sepsis (TESTS): multicentre, double blinded, randomised, placebo controlled, phase 3 trial | BMJ (Clinical research ed.) | PMID 39814420 |
| 2022 | Randomised controlled trial | Immune enhancement in patients with predicted severe acute necrotising pancreatitis: a multicentre double-blind randomised controlled trial | Intensive care medicine | PMID 35713670 |
| 2023 | Randomised controlled trial | A randomized controlled pilot trial of etanercept and alpha-1 antitrypsin to improve autologous islet engraftment | Pancreatology : official journal of the International Association of Pancreatology (IAP) ... [et al.] | PMID 36443174 |
| 2022 | Randomised controlled trial | Value of Thymosin α1 Combined With Blood Purification to Increase Successful Rescues of Shock Patients | Alternative therapies in health and medicine | PMID 35951068 |
| 2023 | Randomised controlled trial | The effect of brief exposure to virtual nature on mental wellbeing in adolescents | Scientific reports | PMID 37853074 |
| 2011 | Randomised controlled trial | Thymosin alpha 1 is associated with improved cellular immunity and reduced infection rate in severe acute pancreatitis patients in a double-blind randomized control study | Inflammation | PMID 20549321 |
| 2026 | Clinical trial | Neoadjuvant immunochemotherapy plus thymalfasin in locally advanced gastric cancer: a prospective clinical trial | BMC medicine | PMID 41749205 |
| 2000 | Randomised controlled trial | A randomized, controlled study of thymosin-alpha1 therapy in patients with anti-HBe, HBV-DNA-positive chronic hepatitis B | Digestive diseases and sciences | PMID 10759236 |
| 2005 | Randomised controlled trial | The efficacy and safety of thymosin alpha-1 in Japanese patients with chronic hepatitis B; results from a randomized clinical trial | Journal of viral hepatitis | PMID 15850471 |
| 1994 | Clinical trial | Bacillus Calmette-Guérin therapy for high-risk superficial bladder cancer | Scandinavian journal of urology and nephrology | PMID 7886412 |
| 2025 | Randomised controlled trial | The efficacy of Lacticaseibacillus paracasei MSMC39-1 and Bifidobacterium animalis TA-1 probiotics in modulating gut microbiota and reducing the risk of the characteristics of meta | PloS one | PMID 39792908 |
| 2005 | Randomised controlled trial | A randomized, controlled, clinical study of thymosin alpha-1 versus interferon-alpha in [corrected] patients with chronic hepatitis B lacking HBeAg in China [corrected] | Journal of the Chinese Medical Association : JCMA | PMID 15759817 |
| Registration | Phase | Status | Enrolment | Title |
|---|---|---|---|---|
| NCT00082082 | PHASE2 | COMPLETED | — | A Trial of Thymalfasin in Adult Patients With Hepatocellular Carcinoma |
| NCT02366247 | PHASE3 | UNKNOWN | 463 | Phase Ⅲ Trial for Combination Treatment of PEG-Tα1 and Adefovir for HBeAg-positive Chronic Hepatitis B |
| NCT00580450 | PHASE1, PHASE2 | UNKNOWN | 9 | Thymosin Alfa 1 in Recipients of Allogeneic Hematopoietic Transplantation for Hematological Malignancies |
| NCT07644897 | PHASE2 | RECRUITING | 55 | Thymosin Alpha 1 Combined With Anti-PD-1 Monoclonal Antibody in Elderly Patients With Advanced Melanoma |
| NCT06056804 | PHASE2 | ACTIVE_NOT_RECRUITING | 20 | Neoadjuvant Chemoradiotherapy Combined With PD-1 Inhibitor and Thymalfasin for pMMR/MSS Locally Advanced Mid-low Rectal Cancer |
| NCT00291616 | PHASE4 | COMPLETED | 52 | Efficacy Study of Thymosin alpha1 & Pegylated Interferon-alpha2a to Treat Chronic Hepatitis B |
| NCT02545751 | PHASE2 | UNKNOWN | 29 | SBRT Combined With Thymalfasin for Metastatic Esophageal Cancer |
| NCT07103408 | PHASE2 | NOT_YET_RECRUITING | 56 | A Study Evaluating Concurrent Chemoradiotherapy Combined With Dual Immune Checkpoint Blockade for Limited-stage Small Cell Lung Cancer |
This table is retrieved from PubMed and ClinicalTrials.gov rather than assembled by hand, so it shows what is indexed — including the absences. Last retrieved 2026-09-09.
Reported dosing ranges
Thymosin Alpha-1 dosing cannot be translated from a study table into personal instructions. The retrieved citation set identifies human study contexts, but the supplied records for this page do not provide extractable dose ranges.
That matters. Without the full protocol details, it would be unsafe and misleading to publish a “typical” dose.
| Study context | Source | Dose or range available from supplied record | How to read this |
|---|---|---|---|
| Sepsis | TESTS phase 3 randomized trial 1 | Not available in the supplied record | This confirms a studied context, not a patient dosing range. |
| Shock with blood purification | Randomized study 4 | Not available in the supplied record | Combination-care studies cannot be turned into self-use instructions. |
| Predicted severe acute necrotising pancreatitis | Multicenter double-blind RCT 2 | Not available in the supplied record | The record supports the study setting, not a dose recommendation. |
| Severe acute pancreatitis | Double-blind randomized study 3 | Not available in the supplied record | The reported immune and infection outcomes apply to that study population. |
| Chronic hepatitis B | Randomized controlled trials 5 6 | Not available in the supplied record | Hepatitis B trial dosing should not be reused outside clinician-supervised care. |
| Cancer-treatment combinations | Phase 2 and prospective clinical trials 7 8 | Not available in the supplied record | Combination oncology protocols are not stand-alone peptide protocols. |
Legal status
Our regulatory log holds no confirmed federal action for Thymosin Alpha-1. That means we have not found one with a primary source — not that none exists.
This section is generated from a dated log of federal actions rather than written by hand, and it is re-checked daily against the Federal Register and FDA sources. Last checked 2026-09-09. See the full legal-status tracker for every compound we follow.
Safety
Thymosin Alpha-1 safety has been evaluated in several human trials, including the TESTS sepsis trial and chronic hepatitis B studies that explicitly studied efficacy and safety 1 6. But the supplied records do not provide a complete adverse-event table.
That means the honest answer is limited: we can say safety was studied in these clinical trials, but we cannot list a reliable rate of headache, injection-site reaction, infection, lab change, or serious adverse event from the supplied records alone.
Adverse events reported in randomized and clinical studies
The retrieved evidence includes randomized and clinical trials in very different populations: sepsis, shock, severe pancreatitis, chronic hepatitis B, metastatic solid tumors, and gastric cancer 1 2 4 5 7 8. These populations have different baseline risks, background treatments, and monitoring.
Because of that, side effects from one setting may not predict side effects in another. Cancer-treatment combinations are especially hard to interpret because Ta1 was given with other therapies, including a PD-1 inhibitor, radiotherapy, GM-CSF, chemotherapy, or immunochemotherapy 7 8.
Safety limits: short follow-up, study populations, and combination treatments
Many peptide safety questions depend on dose, route, duration, medical history, immune status, and the quality of the supplied medication. The retrieved records do not establish long-term safety for wellness, anti-aging, or general immune use.
Supply quality is also a real safety issue. Products sold as “research use only” are not made as patient medications; identity, sterility, impurities, and concentration may be uncertain. Our guide to finding a legitimate peptide source explains why licensed clinical care and pharmacy quality controls matter.
Who should be especially cautious?
People with immune-system disease, cancer, chronic infection, transplant history, organ failure, or complex medication lists should be especially cautious because the retrieved studies involve immune-active settings and, in some cases, combination treatment regimens 5 7 8.
Pregnancy, breastfeeding, and pediatric use require extra caution because the supplied evidence set does not establish safety for those groups.
Interactions
Thymosin Alpha-1 interaction studies are not established in the supplied record set. That is not reassurance; it means the interaction evidence available to this page is thin.
Cancer immunotherapy, biologics, steroids, and immunosuppressive medicines
The strongest interaction concern is conceptual and clinical: Ta1 has been studied with immune-active cancer regimens, including a PD-1 inhibitor and GM-CSF in metastatic solid tumors, and with neoadjuvant immunochemotherapy in gastric cancer 7 8. Any person using cancer immunotherapy, biologic drugs, steroids, or immunosuppressive medicines needs clinician review before considering an immune-modulating peptide.
The hepatitis B trials also show why infection history matters: Ta1 has been studied in specific chronic hepatitis B populations, not as a general antiviral or immune supplement 5 6.
Why a full medication list matters
A clinician needs the full list: prescriptions, over-the-counter drugs, supplements, hormones, peptides, biologics, cancer treatments, and immune-suppressing medicines. This is especially important when a substance is being considered for immune-related goals.
How to obtain it legally
Thymosin Alpha-1 should be approached through a licensed clinician evaluation, not through a no-prescription research-chemical vendor. A clinician review usually looks at your goals, diagnoses, infection history, immune history, cancer history, medications, allergies, and relevant labs.
Chia does not offer Thymosin Alpha-1. We do offer education on peptide safety, including how to think about buying Thymosin Alpha-1 online, but we do not provide this peptide as a Chia treatment.
When a clinician determines that any compounded medication is appropriate, the safer path is a prescription reviewed by a licensed provider and prepared by a state-licensed 503A pharmacy. Compounded drugs are not FDA-approved, and a prescription is never guaranteed.
What research-chemical vendors are not
A “research use only” seller is not the same as a clinician, a prescription, or a licensed pharmacy. The key risks are identity, sterility, impurities, concentration, storage, and lack of medical screening.
If you are new to this category, start with our plain-English overview of peptides explained. It covers what peptides are, why evidence varies so much, and why route and sourcing matter.
How does Thymosin Alpha-1 compare with other immune-modulating peptides?
Thymosin Alpha-1 is best understood as an immune-modulating thymic peptide with human trial evidence in specific disease settings. It is not the same as tissue-repair peptides or anti-inflammatory peptides.
| Peptide | Common shorthand | Main research framing | Key caution |
|---|---|---|---|
| Thymosin Alpha-1 | Ta1, thymalfasin, Zadaxin | Immune modulation studied in sepsis, pancreatitis, hepatitis B, and cancer-treatment combinations 1 2 5 7. | Evidence does not establish wellness or longevity benefit. |
| Thymosin beta-4 / TB-500 | TB4, TB-500 | Discussed separately as a tissue-repair peptide in our TB-500 guide. | Do not assume Ta1 and TB-500 have the same mechanism or evidence. |
| KPV | KPV peptide | Discussed separately among anti-inflammatory peptides. | Anti-inflammatory framing is not the same as proven disease treatment. |
The practical point: names can sound similar, but the evidence does not transfer from one peptide to another. Ta1, TB-500, and KPV should be evaluated on their own data, risks, and clinical context.
Thymosin Alpha-1 is a thymic peptide also known as thymalfasin, Zadaxin, or Ta1. It has been studied as an immune modulator in specific clinical settings such as sepsis, severe pancreatitis, chronic hepatitis B, and cancer-treatment combinations.
Yes. Thymalfasin is another name used for Thymosin Alpha-1. You may also see the names Zadaxin, Ta1, or thymosin α1.
Its evidence grade is A under the rubric used here because multiple human randomized controlled trials are indexed in the retrieved PubMed evidence set. The grade describes study quantity and design, not whether it works, is safe, or is right for any person.
The supplied study records show that safety was evaluated in human trials, but they do not provide a complete adverse-event table for this page. Side effects may vary by dose, route, condition being treated, other medicines, and product quality.
The supplied evidence set does not establish a clear thyroid effect. Anyone with thyroid disease or thyroid medication use should include that history in a clinician review.
This page cannot give personal duration advice. Study protocols are designed for specific conditions and monitoring plans, and the supplied records do not provide a general-use duration.
People with immune-system disease, cancer, chronic infection, transplant history, organ failure, pregnancy, breastfeeding, pediatric use, or complex medication lists should be especially cautious and should not self-direct use.
No. Chia does not offer Thymosin Alpha-1. This page is educational and is meant to help patients understand the evidence, safety limits, and access questions.
References
- 1.PMID 39814420 [randomised controlled trial] Wu J, Pei F, Zhou L, et al. The efficacy and safety of thymosin α1 for sepsis (TESTS): multicentre, double blinded, randomised, placebo controlled, phase 3 trial. BMJ (Clinical research ed.). 2025.
- 2.PMID 35713670 [randomised controlled trial] Ke L, Zhou J, Mao W, et al. Immune enhancement in patients with predicted severe acute necrotising pancreatitis: a multicentre double-blind randomised controlled trial. Intensive care medicine. 2022.
- 3.PMID 20549321 [randomised controlled trial] Wang X, Li W, Niu C, et al. Thymosin alpha 1 is associated with improved cellular immunity and reduced infection rate in severe acute pancreatitis patients in a double-blind randomized control study. Inflammation. 2011.
- 4.PMID 35951068 [randomised controlled trial] Bai L, Qiu X, Ding X, et al. Value of Thymosin α1 Combined With Blood Purification to Increase Successful Rescues of Shock Patients. Alternative therapies in health and medicine. 2022.
- 5.PMID 10759236 [randomised controlled trial] Zavaglia C, Severini R, Tinelli C, et al. A randomized, controlled study of thymosin-alpha1 therapy in patients with anti-HBe, HBV-DNA-positive chronic hepatitis B. Digestive diseases and sciences. 2000.
- 6.PMID 15759817 [randomised controlled trial] You J, Zhuang L, Cheng HY, et al. A randomized, controlled, clinical study of thymosin alpha-1 versus interferon-alpha in [corrected] patients with chronic hepatitis B lacking HBeAg in China [corrected]. Journal of the Chinese Medical Association : JCMA. 2005.
- 7.PMID 39904914 [clinical trial] Yu J, Yin L, Guo W, et al. Hypofractionated radiotherapy combined with a PD-1 inhibitor, granulocyte macrophage-colony stimulating factor, and thymosin-α1 in advanced metastatic solid tumors: a multicenter Phase II clinical trial. Cancer immunology, immunotherapy : CII. 2025.
- 8.PMID 41749205 [clinical trial] Xu H, Li F, Li B, et al. Neoadjuvant immunochemotherapy plus thymalfasin in locally advanced gastric cancer: a prospective clinical trial. BMC medicine. 2026.
About this article
Chia Health Editorial Team — Evidence-reviewed health education
This article is for educational purposes only and is not a substitute for individualized medical advice. Talk to a licensed clinician before starting, stopping, or changing any prescription.
AI tools may assist with research and drafting. Chia's editorial team reviews source use, clarity, treatment information, and safety framing before publication. A clinician is named only after explicit sign-off. Read our editorial standards.
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