VIP

Overview

Vasoactive intestinal peptide, commonly abbreviated VIP, is a 28-amino-acid neuropeptide found naturally throughout the body. It was first identified in the intestine but is now known to be widely distributed in the nervous system, gut, lungs, and immune tissues, where it functions as a signaling molecule and neurotransmitter.

As an endogenous hormone, VIP is part of normal human physiology rather than a manufactured drug. It is involved in relaxing smooth muscle, dilating blood vessels, regulating secretions, and modulating immune and inflammatory responses. Its broad presence reflects the many roles it plays in maintaining normal bodily function.

A synthetic form of VIP, known as aviptadil, has been investigated as an experimental drug. It is important to distinguish the naturally occurring peptide and its legitimate investigational use from unregulated consumer products marketed as VIP, which are a separate and concerning matter discussed later in this article.

How it works

VIP acts by binding to specific receptors on the surface of cells, primarily receptors known as VPAC1 and VPAC2. Activating these receptors typically raises levels of an intracellular messenger called cyclic AMP, which then drives a range of downstream effects depending on the tissue involved.

Through these pathways, VIP relaxes smooth muscle and dilates blood vessels and airways, stimulates certain secretions in the gut and elsewhere, and influences how immune cells behave. In the lungs in particular, it has effects on airway and blood vessel tone and on inflammatory signaling, which is part of the rationale for investigating it in lung conditions.

VIP also has anti-inflammatory and immune-modulating properties in laboratory and animal studies, where it can shift immune responses and reduce certain inflammatory signals. These actions are biologically interesting but complex, and translating them into reliable clinical benefits has proven challenging.

Research & evidence

Much of the human-focused research on VIP concerns its synthetic analog aviptadil. This investigational drug has been studied in acute respiratory conditions, most notably acute respiratory distress syndrome, including in the context of severe COVID-19, where attention focused on its potential effects on lung tissue and inflammation.

Results from this research have been mixed, and aviptadil has not established itself as a proven, approved treatment for these conditions. Clinical findings have not consistently demonstrated clear benefit, and the peptide remains investigational rather than an established therapy. Much of the broader biology of VIP rests on preclinical and laboratory work.

Overall, while VIP is a well-characterized signaling molecule with plausible biological effects, the evidence supporting any therapeutic use is limited and unsettled. Claims that VIP-based products treat or cure illnesses go well beyond what current evidence supports, and any genuine therapeutic role would need to be established through controlled clinical trials.

Safety & legal status

VIP itself is a natural hormone, but that does not make products containing it safe or appropriate to use without oversight. The synthetic analog aviptadil has been used only in investigational, supervised settings, and its safety profile in those contexts is still being characterized. It is not an approved drug for general use.

Of particular concern are intranasal consumer products marketed as VIP, which are unregulated and not approved by health authorities. These products are sometimes promoted with health claims that are not supported by rigorous evidence, and their purity, dosing, and safety are not assured. This article does not provide dosing information for any form of VIP.

From a legal standpoint, VIP is not an approved medicine for self-directed use. Aviptadil remains investigational, and consumer VIP products fall outside legitimate regulatory approval. Anyone considering these products should be aware that they are unproven and that meaningful safety oversight is lacking.

Frequently asked questions

References

Each source links to its original record — peer-reviewed studies, regulator pages, or reference texts, labelled by type. We summarize findings neutrally; a citation is a reference, not an endorsement, and not a claim that its authors reviewed this page.

1. Said SI. Vasoactive intestinal peptide. J Endocrinol Invest. 1986. Peer-reviewed study
2. Hou X, Yang D, Yang G, et al. Therapeutic potential of vasoactive intestinal peptide and its receptor VPAC2 in type 2 diabetes. Front Endocrinol (Lausanne). 2022. Peer-reviewed study
3. Forssmann WG, Triepel J, Daffner C, et al. Vasoactive intestinal peptide in the heart. Ann N Y Acad Sci. 1988. Peer-reviewed study
4. Iwasaki M, Akiba Y, Kaunitz JD. Recent advances in vasoactive intestinal peptide physiology and pathophysiology: focus on the gastrointestinal system. F1000Res. 2019. Peer-reviewed study
5. Wenger GD, O'Dorisio MS, Goetzl EJ. Vasoactive intestinal peptide. Messenger in a neuroimmune axis. Ann N Y Acad Sci. 1990. Peer-reviewed study
6. Klippstein R, Pozo D. Vasoactive Intestinal Peptide (VIP) Nanoparticles for Diagnostics and for Controlled and Targeted Drug Delivery. Adv Protein Chem Struct Biol. 2015. Peer-reviewed study