reviewed april 2026|next review october 2026|88 physicians psi has verified|11469 published studies
VIP (Vasoactive Intestinal Peptide)
Vasoactive intestinal peptide (VIP) is a 28-amino-acid naturally occurring (the body's own) neuropeptide with over 15,000 published studies, acting through VPAC1 and VPAC2 receptors to modulate immune function, vasodilation, circadian rhythm, and gut motility.
Evidence landscape: 11469 published studies
11,469 published items. 41 human studies and 119 animal studies.
- 41 Human
- 119 Animal
- 40 Reviews
- 11269 Other research
VIP itself is not FDA-approved as a standalone therapeutic. Aviptadil (synthetic VIP) received FDA Fast Track designation for ARDS (acute respiratory distress syndrome) in 2020 but has not received full approval. VIP is available through specialty pharmacies (where a licensed pharmacist prepares a medicine from ingredients for an individual patient) as an intranasal formulation with a physician prescription.
Over 15,000 published studies total (one of the largest bodies of research for any peptide). 11,469 items indexed with 41 human studies and 119 animal studies in the PSI database. The basic science foundation is enormous; controlled clinical trials for therapeutic use are sparse.
Signals through VPAC1 and VPAC2 receptors, activating adenylyl cyclase and increasing intracellular cAMP. Inhibits NF-kB signaling, reduces pro-inflammatory cytokine production (TNF-alpha, IL-6), promotes regulatory T cell differentiation, induces vasodilation, and modulates circadian rhythms.
PSI Assessment
With over 15,000 published studies, VIP is one of the most extensively researched neuropeptides in all of biology. It modulates immune function, blood pressure, gut motility, circadian rhythms, and neuroprotective pathways through VPAC1 and VPAC2 receptor signaling. The basic science foundation is deep. The clinical translation is sparse. The Shoemaker protocol adopted VIP as the final step in chronic inflammatory response syndrome (CIRS) treatment, and the community use is extensive, but controlled clinical trials validating this application have not been published. The very short half-life (approximately 1-2 minutes in circulation) creates significant delivery challenges that limit clinical development.
Over 15,000 published studies. One of the most extensively researched neuropeptides in biology. Controlled clinical trials for therapeutic use are sparse despite the enormous basic science foundation.
The mechanism centers on VPAC1 and VPAC2 receptor activation. These G-protein coupled receptors activate adenylyl cyclase, increasing intracellular cAMP. The downstream effects are broad: NF-kB inhibition reduces pro-inflammatory cytokine production (TNF-alpha, IL-6, IL-12), regulatory T cell differentiation promotes immune tolerance, smooth muscle relaxation causes vasodilation and bronchodilation, and suprachiasmatic nucleus signaling modulates circadian rhythms. The Shoemaker CIRS protocol uses intranasal VIP to reduce inflammatory markers (TGF-beta-1, C4a, MMP-9) in patients after biotoxin exposure. This protocol has not been validated in randomized controlled trials.
What the evidence supports
VIP modulates immune function through VPAC1 and VPAC2 receptor activation, inhibiting NF-kB signaling and reducing pro-inflammatory cytokine production (TNF-alpha, IL-6). The basic science foundation exceeds 15,000 published studies, one of the largest for any peptide. Anti-inflammatory, vasodilatory, and neuroprotective mechanisms are documented across independent groups. 41 human studies provide clinical data across multiple organ systems.
What is not yet established
Whether intranasal VIP administration produces clinically meaningful improvement in CIRS or mold illness. The Shoemaker protocol has not been validated in controlled clinical trials. Whether VIP can be developed as a therapeutic for pulmonary hypertension or IBD given the very short half-life. Optimal delivery route and dosing for each potential indication.
Research Evidence
The findings below cover what the enormous basic science foundation has established and where the evidence thins for clinical application.
Evidence by condition
Evidence dimensions across VIP research areas. The basic science is deep across all areas. Controlled clinical trials are sparse for all therapeutic applications. Pulmonary hypertension has small human studies. CIRS/mold illness has community use without controlled trials.
| Condition | Mechanism | Animal evidence | Human evidence | Replication |
|---|---|---|---|---|
| CIRS/Mold Illness | ||||
| Pulmonary Hypertension | ||||
| IBD | ||||
| Neuroprotection |
VIP has over 15,000 published studies, making it one of the most extensively researched neuropeptides in biology. The anti-inflammatory mechanism through VPAC1/VPAC2 receptor activation, NF-kB inhibition, and cytokine modulation is documented across hundreds of independent research groups.
The basic science foundation is not in question. The gap is between mechanism characterization and controlled clinical therapeutic evidence. Many well-characterized biological molecules do not translate into effective therapeutics.
VIP inhibits NF-kB signaling and reduces production of pro-inflammatory cytokines including TNF-alpha, IL-6, and IL-12. It promotes regulatory T cell differentiation and shifts immune balance toward tolerance. These effects are reproducible across multiple animal models of autoimmune and inflammatory disease.
The anti-inflammatory mechanism is well-characterized and independently replicated. Whether this mechanism can be therapeutically exploited given VIP's 1-2 minute half-life is the translational challenge.
The Shoemaker CIRS protocol uses intranasal VIP to reduce inflammatory markers in patients after biotoxin exposure. Community reports are positive. Controlled clinical trials validating this application have not been published. The CIRS diagnosis itself is debated in mainstream medicine.
The community use for CIRS/mold illness is extensive. The absence of randomized controlled trials means the efficacy question remains open. The debate around CIRS as a diagnosis adds an additional layer of uncertainty.
41 Human|119 Animal|40 Reviews
View all 11469 indexed studiesHow VIP (Vasoactive Intestinal Peptide) Works
VIP (vasoactive intestinal peptide) is a 28-amino-acid neuropeptide, which means it is a short chain of building blocks that normally make up proteins, produced by nerve cells throughout the body. It functions as a signaling molecule that calms inflammation, relaxes blood vessels, and helps regulate gut and brain function.
VIP works like a master calming signal. It tells blood vessels to relax (lowering blood pressure), tells the immune system to reduce inflammation, and helps regulate your gut and breathing. When your body is stuck in a chronic inflammatory state, VIP may help reset the system by dampening the overactive immune response.
For a more detailed view of the biology, here is what researchers have observed at the molecular level.
VIP signals through VPAC1 and VPAC2 receptors, G-protein coupled receptors that activate adenylyl cyclase and increase intracellular cAMP. Downstream signaling inhibits NF-kB activation, reducing TNF-alpha, IL-6, and IL-12 production. VIP promotes regulatory T cell (Treg) differentiation and shifts immune balance toward tolerance (Th2/Treg). It induces vasodilation via smooth muscle relaxation, bronchodilation, and modulates circadian rhythms through the suprachiasmatic nucleus. The half-life is approximately 1-2 minutes in circulation, which is the primary pharmacokinetic limitation for therapeutic development.
What is VIP (Vasoactive Intestinal Peptide) being studied for?
Researchers are studying VIP (Vasoactive Intestinal Peptide) across several health conditions. Each condition below is labeled with the strength of evidence that exists for that specific use, not for VIP (Vasoactive Intestinal Peptide) overall. This means a compound can have human studies for one condition but only animal data for another.
CIRS/Mold Illness
·PreclinicalVIP is used in the Shoemaker protocol for CIRS/mold illness as the final step in a multi-stage treatment. Community reports are positive but controlled clinical trial data is absent.
Limitations: Based primarily on observational data from one clinical group. No randomized controlled trials. The CIRS diagnosis itself is debated in mainstream medicine.
Pulmonary Hypertension
·Animal StudiesVIP relaxes pulmonary blood vessels and has been studied for pulmonary arterial hypertension. Inhaled VIP showed benefit in small clinical studies.
Limitations: Studies are small and uncontrolled. VIP has not been developed as a pharmaceutical for this indication.
IBD
·Animal StudiesVIP has potent anti-inflammatory effects in the gut. Animal models show significant benefit in colitis.
Limitations: No controlled human trials for IBD despite strong animal model rationale.
Neuroprotection
·Animal StudiesVIP protects neurons from oxidative stress, inflammation, and excitotoxicity in animal models.
Limitations: No human neuroprotection trials. Translation from animal models is uncertain.
Safety and Regulatory Status
FDA Status: VIP itself is not FDA-approved for any indication. Aviptadil (synthetic VIP) received FDA Fast Track designation for ARDS in 2020 but has not received full approval.
Availability: Available through specialty pharmacies (where a licensed pharmacist prepares a medicine from ingredients for an individual patient) as an intranasal formulation with a physician prescription. Also available as a research compound.
Class context: VIP is a naturally occurring (the body's own) neuropeptide. Generally well tolerated in limited clinical use. Reported side effects include facial flushing, nasal congestion (intranasal route), and transient hypotension from vasodilation. The very short half-life (1-2 minutes) limits systemic exposure.
VIP is naturally occurring (the body's own) and generally well tolerated in limited clinical use. Reported side effects include facial flushing, nasal congestion (intranasal route), and transient hypotension from vasodilation. The very short half-life of approximately 1-2 minutes in circulation limits systemic exposure, which is favorable from a safety perspective.
Questions and Comparisons
Questions the evidence raises for a VIP (Vasoactive Intestinal Peptide) discussion.
Comparison and Related Research
VIP is most often compared with other immune-modulating peptides. The comparisons below outline how each differs.
Related compounds
Frequently Asked Questions
References
Each citation links to the original study on PubMed, the U.S. National Library of Medicine database.
- 1.The original discovery paper identifying vasoactive intestinal peptide. Isolated from porcine small intestinal wall, VIP was characterized as a 28-amino acid peptide with potent vasodilatory activity. This landmark study established VIP as a new class of regulatory peptide and launched decades of research into its diverse physiological roles.Said SI & Mutt V., 1970 in Science. View on PubMed
- 2.A comprehensive review of the immunomodulatory properties of VIP, covering its effects on both innate and adaptive immunity. Documented how VIP shifts the immune response from a pro-inflammatory Th1 profile toward an anti-inflammatory Th2 profile, reduces production of inflammatory cytokines, and promotes regulatory T-cell generation. This paper established the scientific basis for VIP as a potential therapeutic agent in inflammatory and autoimmune conditions.Delgado M et al., 2004 in Pharmacol Rev. View on PubMed
- 3.A clinical study evaluating inhaled VIP in patients with active pulmonary sarcoidosis. Demonstrated that VIP inhalation shifted bronchoalveolar lavage fluid cytokine profiles from pro-inflammatory to anti-inflammatory patterns, providing human evidence for VIP's immunomodulatory mechanism. This was one of the first prospective clinical evaluations of VIP as an anti-inflammatory agent.Prasse A et al., 2010 in Am J Respir Crit Care Med. View on PubMed
- 4.Demonstrated the link between vagal nerve stimulation and VIP release in the cardiovascular system. Showed that endogenous VIP released via vagal pathways significantly increases coronary artery blood flow through vasodilation, establishing a physiological role for VIP in cardiac circulation and providing evidence for its hemodynamic effects.Feliciano L & Henning RJ., 1998 in Cardiovasc Res. View on PubMed
Medical Disclaimer
This content is for educational and informational purposes only and does not constitute medical advice. The information presented reflects published research as indexed by PSI and should not be used to make treatment decisions. Always consult a qualified healthcare provider before starting, stopping, or modifying any treatment.