28-amino-acid neuropeptide researched for immune regulation, neuroprotection, and circadian rhythm modulation.
Last Updated: August 2026
VIP (Vasoactive Intestinal Peptide) is a 28-amino-acid neuropeptide widely distributed throughout the central and peripheral nervous systems, gastrointestinal tract, and immune system. It activates VPAC1 and VPAC2 receptors to produce vasodilation, smooth muscle relaxation, immune modulation, and circadian rhythm effects. VIP is researched for multiple chronic inflammatory and immune-mediated conditions and has been included in proposed protocols for chronic inflammatory response syndrome (CIRS) and biotoxin illness, though those protocols rest on contested clinical frameworks. VIP is not FDA-approved and is sold as a research-use-only compound by third-party laboratories.
VIP (Vasoactive Intestinal Peptide) is a 28-amino-acid neuropeptide that binds VPAC1 and VPAC2 G-protein-coupled receptors, activating cAMP signaling in target tissues. Effects include vasodilation, bronchodilation, smooth muscle relaxation, intestinal secretion, modulation of T-cell and macrophage function (generally anti-inflammatory), and circadian rhythm regulation through the suprachiasmatic nucleus. Native VIP has short half-life (minutes), requiring formulation strategies or analog development for sustained effects. Evidence level: Established neuropeptide biology; Phase 2 human trials (sarcoidosis, ARDS, asthma); used in research and complementary contexts for chronic inflammatory conditions.
VIP has been studied in Phase 2 trials for sarcoidosis, acute respiratory distress syndrome, asthma, and various inflammatory conditions with mixed results. The compound has gained attention in chronic inflammatory response syndrome (CIRS) and Shoemaker-protocol contexts for biotoxin illness, though those clinical frameworks are contested in mainstream medicine. Aviptadil (a synthetic VIP analog) advanced into late-stage clinical development for COVID-19 ARDS during the pandemic with mixed results. Evidence level: Phase 2 across multiple conditions; CIRS protocol use is contested at evidence-based standards.
VIP operates through a defined GPCR mechanism (VPAC1/2) distinguishing it from cathelicidins like LL-37 or proposed-mechanism bioregulators. Its broad effects across immune, vascular, and circadian systems make it mechanistically distinctive.
| Compound | Receptor mechanism | Primary research focus | Clinical stage |
|---|---|---|---|
| VIP | VPAC1/VPAC2 GPCRs | CIRS, sarcoidosis, asthma, ARDS | Phase 2 multiple |
| Thymosin Alpha-1 | TLR9, T-cell differentiation | Hepatitis B/C | Phase 3 |
| LL-37 | Antimicrobial + immune | Antibacterial, wound healing | Phase 2 (derivatives) |
| KPV | NF-κB inhibition | Gut, skin inflammation | Preclinical + early clinical |
VIP administration commonly produces transient effects related to its vasodilator activity — flushing, hypotension, headache — particularly with intranasal or subcutaneous routes at higher doses. Long-term safety in chronic-use contexts is not well-characterized in human RCT. The CIRS-protocol use of intranasal VIP has community-reported safety experience but limited formal long-term safety data. Evidence level: Phase 2 safety; community use safety reports; long-term RCT data limited.
VIP is not FDA-approved for any indication as of May 2026. Aviptadil, a synthetic VIP, has been through formal clinical development (including for COVID-19 respiratory failure) and is not FDA-approved in the United States. Approval claims for aviptadil-containing combination products in some other countries exist in circulation but could not be independently verified, so they are not asserted here (as of August 2026). Research-grade VIP is sold by third-party laboratories. The CIRS-protocol use of intranasal VIP operates as physician-directed compounding in some practice contexts but not under specific FDA indication approval. Regulatory context in FDA peptide regulation 2025–2026 timeline.
VIP's 28-amino-acid length and the various formulation routes used in research (intranasal, subcutaneous, intravenous) create varied quality requirements — intranasal formulations have particular stability and excipient considerations not addressed by basic peptide HPLC. Independent third-party HPLC testing and mass spectrometry identity confirmation are essential. Guidance in how-to-test-peptides hub.
Peptigrity collects independent third-party Certificates of Analysis for VIP from shops' official channels and verifies each for authenticity before publishing. Because shops choose which COAs to publish, results reflect the batches shops have made public rather than every production batch — a selection bias we state openly. A community-funded Testing Grant to purchase and test vials anonymously is in development. Tests in the database come from independent labs such as Janoshik Analytical, Freedom Diagnostics, and Chromate. Methodology in how we calculate trust scores.
VIP activates VPAC1 and VPAC2 receptors to produce vasodilation, smooth muscle relaxation, immune modulation, and circadian effects — with research interest in sarcoidosis, asthma, ARDS, and chronic inflammatory response syndrome (CIRS) contexts. Clinical evidence varies by indication; the CIRS framework specifically is contested at evidence-based medicine standards.
VIP is legal to purchase as a research chemical for laboratory use in most jurisdictions, but it is not approved for human consumption. Country breakdown in peptide legal status guide.
The chronic inflammatory response syndrome (CIRS) framework and Shoemaker-protocol use of VIP are contested within mainstream medicine. The framework has community and clinical practitioner support but limited formal RCT evidence at evidence-based-medicine standards. Anyone considering VIP for CIRS-protocol use should evaluate the underlying clinical framework critically and consult licensed physicians.
Independent third-party HPLC certificate of analysis from a lab the vendor does not own or pay, with mass spectrometry identity confirmation. Intranasal formulations have additional considerations not addressed by basic peptide testing. COA interpretation in red flags in peptide certificates of analysis.
No. VIP is not approved for human consumption and Peptigrity is an independent review platform, not a medical authority. Research-use and CIRS-protocol dosing varies by route. Anyone considering use should consult a licensed physician.
No. VIP is the native 28-amino-acid neuropeptide; Aviptadil is a synthetic VIP analog developed for formal clinical use. They are mechanistically related but not identical products.
This section is for educational and informational purposes only and does not constitute medical advice. VIP is not approved by the FDA or any major Western regulator for human use. The CIRS / Shoemaker-protocol framework for VIP use is contested within mainstream medicine. Always consult a qualified healthcare provider before using any peptide or research compound. Peptigrity is an independent review platform and does not sell, endorse, or recommend specific products or vendors.
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