Thymosin Alpha-1 for Immune System: What the Evidence Shows
What human and animal studies show about Thymosin Alpha-1 for immune system, how strong that evidence is, and what is still unproven.
- Strongest evidence
- Human RCT
- Human studies
- 222
- PubMed records, our ledger
- Animal studies
- 101
- PubMed records, our ledger
- Studies we summarised
- 10
- with an outcome for immune system
Evidence for immune system
Each row is an outcome related to immune system from a published study, strongest design first. Animal and cell results are labelled and are not human results. User reports are not counted as evidence here.
| Outcome | Result | Study type | Source |
|---|---|---|---|
| 28-day all-cause mortality | 28-day mortality was 23.4% on thymosin alpha 1 and 24.1% on placebo (hazard ratio 0.99, P=0.93). | Human RCTn = 1106 | BMJ 2025, PMID 39814420 |
| Safety and secondary outcomes | No secondary or safety outcome differed significantly from placebo. | Human RCTn = 1106 | BMJ 2025, PMID 39814420 |
| Infection rate and ICU stay | Culture-positive rates and ICU stay were lower with thymosin alpha 1. | Human RCTn = 24 | Inflammation 2011, PMID 20549321 |
| Non-recovery rate | After adjustment, thymosin alpha 1 use was associated with a higher non-recovery rate (OR 1.5); sicker patients were more likely to be treated. | Human observationaln = 2282 | Frontiers in immunology 2021, PMID 34408744 |
| CD4+ T cell recovery | CD4+ and CD8+ T cell increases did not differ between treated and untreated groups (p=0.851 and p=0.842). | Human observationaln = 275 | Frontiers in immunology 2021, PMID 34149679 |
| 28-day mortality in critical type | In the critical-type subgroup, thymosin alpha 1 was associated with lower 28-day mortality (HR 0.11, P=0.013). | Human observationaln = 334 | International immunopharmacology 2020, PMID 32795897 |
| All-cause mortality | Pooled all-cause mortality was lower (RR 0.53) but certainty is very low. | Meta-analysisn = 1349 | The Cochrane database of systematic reviews 2026, PMID 42713852 |
| 28-day mortality (all RCTs) | Pooling all included RCTs, thymosin alpha 1 reduced 28-day mortality (OR 0.73, P = 0.003). | Meta-analysisn = 1927 | Frontiers in cellular and infection microbiology 2025, PMID 40969554 |
| High-quality and multicentre trials | High-quality (OR 0.82) and multicentre (OR 0.86) subgroups showed no significant mortality benefit. | Meta-analysisn = 1927 | Frontiers in cellular and infection microbiology 2025, PMID 40969554 |
| COVID-19 mortality | Mortality was lower (RR 0.59, p = 0.02) but ventilation need and hospital stay did not differ; heterogeneity was high. | Meta-analysis | Inflammopharmacology 2023, PMID 37845598 |
| COVID-19 mortality | Overall mortality did not differ (RR 1.03, p = 0.92); the authors do not support use in hospitalized adults. | Meta-analysisn = 5352 | International immunopharmacology 2023, PMID 36527881 |
| Mortality | Pooled mortality was lower with thymosin alpha 1 (RR 0.59, p = 0.0001); the authors rate the evidence as low quality. | Meta-analysisn = 530 | BMC infectious diseases 2016, PMID 27633969 |
PubMed records for Thymosin Alpha-1 and immune system: 222 human, 101 animal (search counts, not studies we reviewed). Grades follow our evidence scale.
How strong is it?
A human randomized trial outweighs any number of animal studies. Animal and cell results show a mechanism worth testing, not that it works in people.
Other peptides people research for immune system
No other peptide in our index has a immune system page yet.
All peptides for immune system, comparedCommon questions
Does Thymosin Alpha-1 help with immune system?
The strongest study we summarise for immune system is human rct evidence, across 10 studies with an outcome for immune system. A trial result is not an approval; see the legal status.
Is Thymosin Alpha-1 approved for immune system?
Thymosin Alpha-1 is Not FDA approved · approved abroad. Which conditions that approval covers is set by the label; use for anything else is off-label.
What is the best peptide for immune system?
There is no single answer. Our immune system overview compares each candidate by evidence grade and legal status rather than by popularity.
More on Thymosin Alpha-1
Sources
- 1The efficacy and safety of thymosin α1 for sepsis (TESTS): multicentre, double blinded, randomised, placebo controlled, phase 3 trial.BMJ (Clinical research ed.) · 2025PMID 39814420Accessed 2 Oct 2026
- 2Thymosin 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 · 2011PMID 20549321Accessed 2 Oct 2026
- 3Efficacy of Thymosin Alpha 1 in the Treatment of COVID-19: A Multicenter Cohort Study.Frontiers in immunology · 2021PMID 34408744Accessed 2 Oct 2026
- 4Thymosin Alpha-1 Has no Beneficial Effect on Restoring CD4+ and CD8+ T Lymphocyte Counts in COVID-19 Patients.Frontiers in immunology · 2021PMID 34149679Accessed 2 Oct 2026
- 5Thymosin α1 therapy in critically ill patients with COVID-19: A multicenter retrospective cohort study.International immunopharmacology · 2020PMID 32795897Accessed 2 Oct 2026
- 6Thymosin-ɑ1 for people with chronic hepatitis B.The Cochrane database of systematic reviews · 2026PMID 42713852Accessed 2 Oct 2026
- 7Efficacy of thymosin α1 for sepsis: a systematic review and meta-analysis of randomized controlled trials.Frontiers in cellular and infection microbiology · 2025PMID 40969554Accessed 2 Oct 2026
- 8The efficacy of thymosin alpha-1 therapy in moderate to critical COVID-19 patients: a systematic review, meta-analysis, and meta-regression.Inflammopharmacology · 2023PMID 37845598Accessed 2 Oct 2026
- 9Thymosin alpha1 use in adult COVID-19 patients: A systematic review and meta-analysis on clinical outcomes.International immunopharmacology · 2023PMID 36527881Accessed 2 Oct 2026
- 10The efficacy of thymosin α1 as immunomodulatory treatment for sepsis: a systematic review of randomized controlled trials.BMC infectious diseases · 2016PMID 27633969Accessed 2 Oct 2026
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