There are no proven best peptides for lung health. The two most-studied candidates, thymosin alpha-1 and vasoactive intestinal peptide (VIP, as the drug aviptadil), did not improve outcomes in their largest trials: aviptadil failed to improve recovery in 461 people with COVID-19 respiratory failure, and thymosin alpha-1 did not lower deaths in 1,089 adults with sepsis.[2][5] Neither is FDA-approved, and proven lung care, starting with not smoking, matters far more.[1][7]
This guide lays out what was tested and what was found. For more on immune and longevity peptides, see our longevity peptides hub.
Evidence at a glance
| Peptide or drug | Evidence level | What was shown | FDA status | Our profile |
|---|---|---|---|---|
| Smoking cessation, inhaled medicines, vaccines, pulmonary rehab (standard care) | Human RCTs and guidelines | Core of COPD care in the GOLD report[1] | Approved treatments (not peptides) | — |
| VIP (aviptadil), IV | Human RCTs | No significant benefit in COVID-19 respiratory failure (TESICO)[2] | Not approved[7] | VIP |
| Thymosin alpha-1 | Human RCTs and meta-analysis | No effect on COVID-19 deaths; no effect on sepsis deaths[4][5] | Not approved in the US[7] | Thymosin alpha-1 |
| BPC-157 | Animal or lab only | No human lung trials | Not approved[6] | BPC-157 |
| LL-37 | No evidence for lung health | No human lung trials | Not approved[6] | LL-37 |
Proven lung care comes first
For chronic lung disease, the strongest evidence is for treatments that are not peptides. The Global Initiative for Chronic Obstructive Lung Disease (GOLD) report, the main international guide for COPD, centers care on:[1]
- Stopping smoking, the single most effective step to slow lung damage
- Inhaled bronchodilators, with inhaled steroids for some patients
- Vaccinations to prevent respiratory infections
- Pulmonary rehabilitation, a supervised exercise and education program
- Oxygen for people with low blood oxygen levels
Asthma, lung fibrosis and other conditions have their own proven treatments, prescribed by a doctor after testing such as spirometry.
VIP (aviptadil): promising theory, negative trials
Vasoactive intestinal peptide is a 28-amino-acid hormone found in the lungs and gut. Lab studies suggested it could protect lung cells, which made it a candidate during the COVID-19 pandemic. In nonclinical work, VIP increased surfactant (the film that keeps air sacs open), dampened inflammatory signals and blocked the virus from copying itself in lung cells.[3] Aviptadil is the synthetic version.
Early randomized trial (2022). In 196 critically ill COVID-19 patients at 10 US hospitals, randomly assigned 2 to 1 to three days of IV aviptadil or placebo, the drug missed its primary goal of being alive and free of respiratory failure at day 60. The authors highlighted a secondary survival finding, but a missed primary endpoint means the trial did not show the drug works.[3]
TESICO (2023). This larger NIH-funded trial randomly assigned 461 hospitalized adults with COVID-19 respiratory failure, 94% in intensive care, to IV aviptadil or placebo. Aviptadil did not significantly improve clinical outcomes up to day 90.[2]
How it was run: patients at 28 US sites, all within four days of developing respiratory failure, received a 12-hour infusion on each of three days, with the dose rising each day. By day 90, 38% of the aviptadil group and 36% of the placebo group had died. Serious problems in the first five days, such as organ failure, serious infection or severe adverse events, occurred in 63% versus 56%, a difference that was not statistically significant.[2]
VIP is not FDA-approved for any use.[7] It is also promoted as a nasal spray for mold-related illness; our VIP for CIRS guide reviews that very limited evidence.
Thymosin alpha-1: widely used abroad, weak results
Thymosin alpha-1 (thymalfasin) is a 28-amino-acid peptide first isolated from the thymus. It is used as an immune modulator in some countries and was widely given to COVID-19 patients, especially in China.
COVID-19 meta-analysis (2023). Across 9 studies with 5,352 patients, thymosin alpha-1 had no overall effect on death. Some subgroups looked better, such as older or more severely ill patients, but the authors concluded the results do not support its use in hospitalized adults with COVID-19.[4] Most included studies were observational, which makes them prone to bias.
Sepsis trial (TESTS, 2025). Sepsis, often caused by pneumonia, is a leading cause of lung failure. In this double-blind phase 3 trial of 1,089 adults in China, 28-day death rates were 23.4% on thymosin alpha-1 versus 24.1% on placebo, a difference that could be due to chance. No secondary outcome differed.[5]
The trial ran at 22 hospitals and gave thymosin alpha-1 or placebo as an injection under the skin every 12 hours for seven days. A planned subgroup analysis hinted that the drug might help people with diabetes but do worse than placebo in people under 60. Subgroup findings like these are not reliable on their own, and the authors concluded there was no clear evidence of benefit. The trial was partly funded by the drug’s manufacturer.[5]
Thymosin alpha-1 is not FDA-approved.[7] FDA lists it among bulk substances nominated for compounding whose nominations raised safety concerns.[6] Our thymosin alpha-1 vs LL-37 guide compares the two immune peptides in detail.
Other peptides marketed for the lungs
- BPC-157 is sometimes promoted for lung repair based on rodent studies. There are no human lung trials.
- LL-37, an antimicrobial peptide made by the body, is promoted for infections. Human trials have been small and limited to topical use on wounds, not lungs.
FDA lists both among compounding substances with safety concerns, citing limited safety information and impurity risks.[6] Products sold as research chemicals for injection or inhalation are not approved, and their contents are not checked. See research-use-only peptides and peptide nasal spray vs injection.
How strong is the evidence?
Questions to ask your doctor
- What is causing my breathing symptoms, and have I had spirometry?
- Am I using my inhalers correctly, and are my vaccines up to date?
- Would pulmonary rehabilitation help me?
- Is there a clinical trial I could join for my condition?
- If I am thinking about a peptide I saw online, what evidence would you need to see first?
- Which symptoms mean I should call you or go to an emergency department?
For more longevity-peptide reviews, see mitochondrial peptides research and epitalon vs TA-65.
