Compound research
Thymosin Alpha-1: Research Overview & Current Status
Thymosin Alpha-1 is a Thymic peptide / immunomodulator. Current research status: approved (non-drug / other indication). Thymalfasin (Zadaxin) is approved in more than 35 countries for chronic hepatitis B, hepatitis C, and as an immunomodulatory agent, but has not been approved by the FDA or EMA. In 2023 the FDA placed additional restrictions on its compounding status in the United States. Sepsis, despite extensive research, has never been an approved indication anywhere.
Live vendor pricing
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Amino Club
Tracked$39.99 / 10mg($39.99 to 10mg)
Checked Aug 7, 2026
Check price at Amino Club →$39.99 / 10mg($39.99 to 10mg)
Checked Aug 10, 2026
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Tracked$39.99 / 10mg($39.99 to 10mg)
Checked Aug 14, 2026
Check price at Rivn Peptides →Step One Ventures
Tracked$44.00 / 10mg($44.00 to 10mg)
Checked Jul 22, 2026
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Tracked$44.99 / 10mg($44.99 to 10mg)
Checked May 14, 2026
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Tracked$45.00 / 10mg($45.00 to 10mg)
Checked Jul 24, 2026
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Tracked$58.00 / 10mg($58.00 to 10mg)
Checked Aug 13, 2026
Check price at EZ Peptides →PeakForce Labs
Tracked$59.00 / 10mg($59.00 to 10mg)
Checked Aug 15, 2026
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Tracked$59.95 / 10mg($59.95 to 10mg)
Checked Jul 31, 2026
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Tracked$60.00 / 10mg($60.00 to 10mg)
Checked Jun 19, 2026
Check price at GLP-1 Research Lab →Premier Research
Tracked$60.00 / 10mg($60.00 to 10mg)
Checked Jul 20, 2026
Check price at Premier Research →Durham Peptides
Tracked$60.63 / 10mg($60.63 to 10mg)
Checked Aug 7, 2026
Check price at Durham Peptides →Glacier Aminos
Tracked$63.99 / 10mg($63.99 to 10mg)
Checked Jul 31, 2026
Check price at Glacier Aminos →Purity Peptides
Tracked$64.09 / 10mg($64.09 to 10mg)
Checked Jul 16, 2026
Check price at Purity Peptides →Polar Peptides
Tracked$64.79 / 10mg($64.79 to 10mg)
Checked Apr 17, 2026
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Tracked$65.00 / 10mg($65.00 to 10mg)
Checked Jun 5, 2026
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Tracked$65.00 / 10mg($65.00 to 10mg)
Checked Aug 3, 2026
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Tracked$65.00 / 10mg($65.00 to 10mg)
Checked Aug 4, 2026
Check price at Atomik Labz →Purus Peptides
Tracked$65.00 / 10mg($65.00 to 10mg)
Checked Aug 6, 2026
Check price at Purus Peptides →Peptide Giants
Tracked$65.99 / 10mg($65.99 to 10mg)
Checked Aug 1, 2026
Check price at Peptide Giants →Elite Edge Biotech
Tracked$33.00 / 5mg($66.00 to 10mg)
Checked Jul 28, 2026
Check price at Elite Edge Biotech →Orbitrex Peptides
Tracked$69.99 / 10mg($69.99 to 10mg)
Checked Aug 3, 2026
Check price at Orbitrex Peptides →Mile High Compounds
Tracked$69.99 / 10mg($69.99 to 10mg)
Checked Aug 3, 2026
Check price at Mile High Compounds →Axon Chems
Tracked$70.00 / 10mg($70.00 to 10mg)
Checked Jul 31, 2026
Check price at Axon Chems →Offline Peptides
Tracked$72.00 / 10mg($72.00 to 10mg)
Checked Jul 28, 2026
Check price at Offline Peptides →Peptide Giants
Tracked$36.25 / 5mg($72.50 to 10mg)
Checked Aug 1, 2026
Check price at Peptide Giants →$75.00 / 10mg($75.00 to 10mg)
Checked Apr 16, 2026
Check price at Ascension Peptides →PeakForm Peptides
Tracked$75.00 / 10mg($75.00 to 10mg)
Checked Aug 1, 2026
Check price at PeakForm Peptides →Noble Sciences
Tracked$39.00 / 5mg($78.00 to 10mg)
Checked Aug 1, 2026
Check price at Noble Sciences →PeakForm Peptides
Tracked$40.00 / 5mg($80.00 to 10mg)
Checked Aug 1, 2026
Check price at PeakForm Peptides →Chameleon Peptides
Tracked$81.90 / 10mg($81.90 to 10mg)
Checked Jul 31, 2026
Check price at Chameleon Peptides →Particle Peptides
Tracked$41.62 / 5mg($83.24 to 10mg)
Checked Jul 24, 2026
Check price at Particle Peptides →Pristine Aminos
Tracked$85.00 / 10mg($85.00 to 10mg)
Checked Aug 2, 2026
Check price at Pristine Aminos →Pulse Peptides
Tracked$43.19 / 5mg($86.38 to 10mg)
Checked Apr 17, 2026
Check price at Pulse Peptides →Modern Aminos
Tracked$44.00 / 5mg($88.00 to 10mg)
Checked May 14, 2026
Check price at Modern Aminos →$89.25 / 10mg($89.25 to 10mg)
Checked Jul 31, 2026
Check price at Amino Vault →Apex Peptide Supply
Tracked$89.99 / 10mg($89.99 to 10mg)
Checked May 14, 2026
Check price at Apex Peptide Supply →Pinnacle Peptide Labs
Tracked$99.99 / 10mg($99.99 to 10mg)
Checked Jul 22, 2026
Check price at Pinnacle Peptide Labs →Woosh Labs
Tracked$99.99 / 10mg($99.99 to 10mg)
Checked Jun 24, 2026
Check price at Woosh Labs →Purity Peptides
Tracked$51.70 / 5mg($103.40 to 10mg)
Checked Jul 16, 2026
Check price at Purity Peptides →Chameleon Peptides
Tracked$53.10 / 5mg($106.20 to 10mg)
Checked Jul 31, 2026
Check price at Chameleon Peptides →Pantheon Peptides
Tracked$54.00 / 5mg($108.00 to 10mg)
Checked Apr 23, 2026
Check price at Pantheon Peptides →SKO Compounds
Tracked$109.99 / 10mg($109.99 to 10mg)
Checked Jul 23, 2026
Check price at SKO Compounds →Swift Peptides
Tracked$109.99 / 10mg($109.99 to 10mg)
Checked Aug 6, 2026
Check price at Swift Peptides →Liv Pure Wellness
Tracked$110.00 / 10mg($110.00 to 10mg)
Checked Apr 14, 2026
Check price at Liv Pure Wellness →CertaPeptides
Tracked$111.06 / 10mg($111.06 to 10mg)
Checked Jun 27, 2026
Check price at CertaPeptides →CertaPeptides
Tracked$22.77 / 2mg($113.85 to 10mg)
Checked Jun 27, 2026
Check price at CertaPeptides →PureBio Labs
Tracked$119.00 / 10mg($119.00 to 10mg)
Checked Aug 5, 2026
Check price at PureBio Labs →Evo Labs Research
Tracked$59.99 / 5mg($119.98 to 10mg)
Checked Jun 22, 2026
Check price at Evo Labs Research →Evolve Peptides
Tracked$60.00 / 5mg($120.00 to 10mg)
Checked Apr 22, 2026
Check price at Evolve Peptides →True Research Labs
Tracked$129.00 / 10mg($129.00 to 10mg)
Checked Aug 15, 2026
Check price at True Research Labs →BioLongevity Labs
Tracked$129.97 / 10mg($129.97 to 10mg)
Checked Aug 2, 2026
Check price at BioLongevity Labs →$130.00 / 10mg($130.00 to 10mg)
Checked May 14, 2026
Check price at Biotech Peptides →Nationwide Peptides
Tracked$67.00 / 5mg($134.00 to 10mg)
Checked Aug 5, 2026
Check price at Nationwide Peptides →PureBio Labs
Tracked$69.99 / 5mg($139.98 to 10mg)
Checked Aug 5, 2026
Check price at PureBio Labs →Swift Peptides
Tracked$70.99 / 5mg($141.98 to 10mg)
Checked Aug 6, 2026
Check price at Swift Peptides →$149.00 / 10mg($149.00 to 10mg)
Checked Apr 16, 2026
Check price at Core Peptides →Pantheon Peptides
Tracked$32.40 / 2mg($162.00 to 10mg)
Checked Apr 23, 2026
Check price at Pantheon Peptides →$81.00 / 5mg($162.00 to 10mg)
Checked Apr 16, 2026
Check price at Core Peptides →Apex Peptides Lab
Tracked$89.00 / 5mg($178.00 to 10mg)
Checked Aug 15, 2026
Check price at Apex Peptides Lab →Alpha Peptides
Tracked$41.44 / 10mg($41.44 to 10mg)
Checked Jul 31, 2026
Check price at Alpha Peptides →Nationwide Peptides
Tracked$99.00 / 10mg($99.00 to 10mg)
Checked Aug 5, 2026
Check price at Nationwide Peptides →CertaPeptides
Tracked$56.38 / 5mg($112.76 to 10mg)
Checked Jun 27, 2026
Check price at CertaPeptides →Thymosin Alpha-1 price report
Thymosin Alpha-1 currently costs as little as $39.99 to obtain 10mg, from Amino Club. Across the 58 vendors we track, the typical cost to 10mg is $79.95, using each vendor's own cheapest listing. 57 of those vendors show current stock, and prices were checked through Aug 15, 2026.
- Lowest to 10mg
- $39.99
- Amino Club
- Median to 10mg
- $79.95
- one offer per vendor
- Lowest package
- $22.77
- 2mg at CertaPeptides
- Vendors tracked
- 58
- 57 in stock
Checked through Aug 15, 2026. Prices are aggregated from public vendor listings. Sources and data licensing are documented on our methodology page.
At a glance
- Category
- immune
- Mechanism class
- Thymic / immune modulator
- Research phase
- Research / preclinical only
- NCAA status
- Not explicitly listed (catchall risk) — Immunomodulatory thymic peptide (FDA-approved for hepatitis B in some countries). NOT the same as Thymosin-β4 (TB-500). Not explicitly listed by NCAA or WADA.
- WADA status
- Prohibited (WADA S2 — Peptide Hormones, Growth Factors, Related Substances)
Overview
Thymosin alpha-1 is a 28-amino-acid peptide originally isolated from thymic tissue extract and later synthesized as thymalfasin, studied for its immune-modulating effects on T-cell function and cytokine signaling. It has an established international regulatory history distinct from most research peptides in this class.
Thymic peptide / immunomodulator
Research timeline
1970s-1980s
Thymosin alpha-1 isolated and characterized from thymic tissue extract; synthetic thymalfasin subsequently developed.
Source →1990s-2000s
Thymalfasin (Zadaxin) approved in 35+ countries for chronic hepatitis B and C and general immune modulation.
Source →2008-2010
ETASS trial (multicenter RCT, six Chinese tertiary hospitals) evaluated thymosin alpha-1 effects on 28-day mortality and immunofunction in severe sepsis.
Source →2016
Meta-analysis of 19 RCTs (530 patients across 10 mortality-reporting trials) reported a significant reduction in mortality with Ta1 (RR 0.59, 95% CI 0.45-0.77).
Source →2016-2020
TESTS trial, a multicenter, double-blind, placebo-controlled Phase 3 trial at 22 Chinese centers, found no significant overall mortality benefit from Ta1 in sepsis, with subgroup analyses suggesting differential age/comorbidity effects.
Source →2020
NCT04487444 registered evaluating thymalfasin (thymosin alpha-1) for treatment of COVID-19 infection.
Source →2023
FDA placed additional restrictions on thymosin alpha-1 compounding status in the United States.
Source →2025
Updated systematic review/meta-analysis of 11 RCTs (1,927 sepsis patients) reported a significant 28-day mortality reduction with Ta1 (OR 0.73, 95% CI 0.59-0.90), while cautioning that evidence reliability remains uncertain.
Source →
Active & recent research
TESTS trial
Definitive multicenter placebo-controlled evaluation of Ta1 for sepsis mortality; found no significant overall benefit but signaled possible age/comorbidity-dependent effects
Thymalfasin for COVID-19 infection
Evaluating immunomodulatory treatment effects of thymalfasin in COVID-19 patients
2025 updated meta-analysis of sepsis RCTs
Re-evaluating 28-day mortality outcomes with Ta1 across the accumulated sepsis trial literature
Key findings
- A 2025 systematic review and meta-analysis of 11 RCTs (1,927 sepsis patients) reported a statistically significant 28-day mortality reduction associated with Ta1 administration (OR 0.73), while explicitly noting the reliability of the underlying evidence remains uncertain.
- The largest and most rigorous trial to date, the placebo-controlled Phase 3 TESTS trial, found no significant overall mortality benefit in the full sepsis population, illustrating a divergence between meta-analytic pooled results and the single largest RCT.
- TESTS trial subgroup analyses suggested a complex, age- and comorbidity-dependent effect pattern, with signals that Ta1 could potentially harm younger sepsis patients while possibly benefiting older patients and those with diabetes, described by researchers as requiring further confirmation.
- Thymalfasin's clearest, most established evidence base remains its approved use (in 35+ countries outside the U.S./EU) for chronic hepatitis B and C, distinct from its investigational sepsis and COVID-19 research.
Safety & regulatory notes
Thymalfasin (Zadaxin) is approved in 35+ countries for hepatitis B/C and immune modulation but has no FDA or EMA approval; the FDA added compounding restrictions in 2023. Sepsis remains an investigational, off-label research area with mixed trial results. The largest placebo-controlled Phase 3 trial did not confirm an overall mortality benefit, despite earlier and more recent meta-analyses suggesting one.
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Where it's sold for research
We haven't built a dedicated vendor-availability page for Thymosin Alpha-1 yet. See our full research-peptide vendor rankings →
Thymosin Alpha-1 FAQ
Is thymosin alpha-1 FDA-approved?+
No. Thymalfasin (Zadaxin) is approved in more than 35 countries for chronic hepatitis B/C and immune modulation, but it has never received FDA or EMA approval, and in 2023 the FDA added compounding restrictions in the U.S.
Does thymosin alpha-1 reduce mortality in sepsis?+
The evidence is mixed. Earlier meta-analyses and a 2025 updated meta-analysis (11 RCTs) reported significant mortality reduction, but the largest, most rigorous placebo-controlled Phase 3 trial (TESTS) found no significant overall benefit, with subgroup effects suggesting the picture is more complex than pooled analyses imply.
Has thymosin alpha-1 been studied for COVID-19?+
Yes. A registered clinical trial (NCT04487444) evaluated thymalfasin as a treatment for COVID-19 infection, reflecting interest in its immunomodulatory properties during the pandemic era.
What is thymosin alpha-1's approved medical use?+
Its clearest approved use, under the brand Zadaxin, is for chronic hepatitis B and hepatitis C and as a general immunomodulatory agent, in jurisdictions outside the U.S. and EU.
Sources for this page (6)
- 1 https://clinicaltrials.gov/study/NCT04487444
- 2 https://www.frontiersin.org/journals/cellular-and-infection-microbiology/articles/10.3389/fcimb.2025.1673959/full
- 3 https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12440967/
- 4 https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4056079/
- 5 https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5025565/
- 6 https://peptideinsight.com/en/peptides/thymosin-alpha-1
Researched together
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