The Compound Report is an educational resource. Nothing on this site constitutes medical advice or encourages personal use of any compound. Always consult a qualified healthcare provider.
Educational reference only. Nothing on this page constitutes medical advice or encourages personal use of this compound. Always consult a qualified healthcare provider before any decision involving your health.
VIP was first isolated from porcine duodenum in 1970 by Said and Mutt. Its name reflects its initial characterization as a potent vasodilator. What followed was one of the most expansive receptor distribution discoveries in neuroscience — a single peptide expressed throughout virtually every system in the body.
Vasoactive Intestinal Peptide occupies a unique position in peptide pharmacology. Most compounds in this book are either research chemicals with narrow, targeted mechanisms or pharmaceutical drugs with specific receptor targets. VIP is neither — it is an endogenous signaling molecule that the body already produces, expressing it in neurons, immune cells, endocrine cells, and autonomic nerve terminals throughout the CNS, ENS, respiratory, cardiovascular, and reproductive systems. When you administer VIP therapeutically, you are not introducing a foreign pharmacological agent — you are supplementing and redistributing a compound the body recognizes and uses continuously. This context is important for understanding both its broad therapeutic potential and its favorable safety profile.
The secretin/glucagon superfamily context: VIP belongs to the same peptide family as secretin, PACAP (Pituitary Adenylate Cyclase-Activating Polypeptide), glucagon, GLP-1, GIP, and GHRH. This structural kinship means the VPAC receptors share some pharmacological architecture with GLP-1 receptors (both are class B GPCRs coupled to adenylate cyclase), which explains some of the metabolic overlap between VIP and GLP-1 agonists without them being the same compound. VIP's sequence: His-Ser-Asp-Ala-Val-Phe-Thr-Asp-Asn-Tyr-Thr-Arg-Leu-Arg-Lys-Gln-Met-Ala-Val-Lys-Lys-Tyr-Leu-Asn-Ser-Ile-Leu-Asn-NH2. The C-terminal amide is essential for receptor binding; modifications to this sequence produce VIP analogues with altered receptor selectivity.
THE CENTRAL TENSION
VIP represents the most complete immunomodulatory, anti-inflammatory, autonomic-normalizing, and neuro-regenerative mechanism in this entire book — and no one in mainstream medicine knows what to do with it. The compound has been in human clinical trials for 20+ years, treats multiple conditions through a mechanism that addresses the pathological substrate of Long-COVID, CIRS, MCAS, and dysautonomia simultaneously, and is produced endogenously by the very immune cells it regulates. It cannot be turned into a standard oral or IV drug because of its 90-second half-life. The intranasal route — developed outside the standard pharmaceutical pipeline by a clinical researcher (Shoemaker) working with a specific patient population (CIRS) — produced extraordinary results across thousands of patients. The pharmaceutical industry has not invested in scaling this approach because the compound cannot be patented effectively. The community uses it because the evidence from the CIRS program is hard to ignore, the mechanism makes complete sense for multiple inflammatory and autonomic conditions, and there is no other intervention that addresses all of these pathways simultaneously.
Chronic Inflammatory Response Syndrome (CIRS), as defined by Shoemaker, is a multi-system, multi-symptom condition triggered by exposure to biotoxins (most commonly water-damaged building mold, Borrelia/Lyme, ciguatera, or dinoflagellate toxins). The condition involves specific inflammatory biomarker profiles: elevated TGF-β1, elevated C4a, elevated MMP9, reduced VEGF, reduced MSH, reduced VIP, dysregulated pituitary axes. Shoemaker's sequential treatment protocol involves 12 steps. Intranasal VIP is step 11 — administered only after the patient has completed prior steps including environmental avoidance, cholestyramine binders, addressing MARCoNS (multiple antibiotic resistant coagulase negative staph in the nasal cavity), and normalizing other biomarkers. Used in this context, intranasal VIP represents the final step in a comprehensive biotoxin recovery program, not a standalone treatment.
Long-COVID patients with dysautonomia, cognitive dysfunction, fatigue, and immune dysregulation show biomarker profiles that overlap substantially with CIRS. The mechanistic case for VIP in Long-COVID: autonomic dysfunction (POTS, dysautonomia) — VIP regulates autonomic nervous system balance through both central (hypothalamic) and peripheral (autonomic nerve terminal) mechanisms; mast cell activation — VIP suppresses mast cell degranulation at VPAC2 receptors, directly addressing the histamine/cytokine storm that underlies many Long-COVID symptoms; neuroinflammation — VIP's anti-inflammatory and neuroprotective effects address the neurological inflammation component; pulmonary — VIP protects AT-II cells, the primary site of SARS-CoV-2 damage. The ACTIV-3b inclusion of aviptadil in NIH's COVID treatment trials in 2025 reflects institutional recognition of this mechanistic logic. Community adoption of VIP for Long-COVID is ahead of the clinical trial evidence but not ahead of the mechanism.
MCAS is characterized by inappropriate mast cell degranulation — releasing histamine, tryptase, prostaglandins, and cytokines — causing multi-system symptoms including anaphylaxis, urticaria, GI disturbance, brain fog, and cardiovascular instability. VIP's direct VPAC2-mediated mast cell suppression makes it one of the few compounds with a mechanistically direct action on the MCAS substrate. Community reports of significant MCAS symptom improvement with VIP are consistent with this mechanism. The important caveat: VIP's vasodilatory properties can also trigger reactions in some MCAS patients who are already vasodilator-reactive — a careful titration approach starting at the lowest dose is essential.
A smaller community of athletes and performance-focused users has adopted VIP for its autonomic nervous system restorative effects — the same mechanism that benefits CIRS and Long-COVID patients applies to any condition of autonomic dysregulation from overtraining, chronic stress, or post-illness HRV suppression. The documented effects on pituitary axis normalization (ACTH/cortisol, ADH/osmolality) are relevant for athletes managing cortisol dysregulation from high training loads. This is a community application extrapolated from the CIRS data with no specific sports performance research.
VIP's mechanism is best understood not as a single action but as a coordinated multi-system regulatory signal. The two receptor subtypes have different tissue distributions and slightly different pharmacological profiles.
Both VPAC1 and VPAC2 are class B G-protein coupled receptors (GPCRs) that activate adenylate cyclase upon VIP binding, increasing intracellular cAMP. This is the same signaling axis as GLP-1R — explaining VIP's overlap with some GLP-1 metabolic effects. The receptor distribution determines the physiological response. VPAC1 is predominantly expressed in: lung tissue (particularly alveolar Type II cells — AT-II); T-lymphocytes (critical for immune modulation); brain (hypothalamus, hippocampus, cortex); liver; small intestine. The AT-II cell VPAC1 distribution is pharmacologically critical — AT-II cells constitute only 5% of lung epithelial cells but produce surfactant and maintain alveolar Type I cells; VPAC1 activation on AT-II cells is the primary mechanism behind VIP's pulmonary protective effects and explains its importance in COVID-19 ARDS treatment. VPAC2 is predominantly expressed in: smooth muscle (particularly vascular and bronchial); mast cells; basal lung mucosa; brain (suprachiasmatic nucleus — directly regulating circadian rhythm); peripheral immune cells.
VIP simultaneously activates eight functionally distinct therapeutic pathways: (1) Immune modulation — VPAC1 on T-lymphocytes shifts the immune response from Th1/Th17 inflammatory phenotypes toward Th2/Treg anti-inflammatory phenotypes; reduces TNF-α, IL-1β, IL-6, IL-12, IFN-γ production; upregulates IL-10 (anti-inflammatory); this is the primary mechanism behind VIP's utility in CIRS, MCAS, and Long-COVID. (2) Mast cell degranulation suppression — VPAC2 on mast cells suppresses IgE-mediated and non-IgE-mediated degranulation, reducing histamine, tryptase, and cytokine release; directly relevant to MCAS treatment. (3) Bronchodilation — VIP is one of the most potent endogenous bronchodilators; VPAC2 on bronchial smooth muscle induces relaxation; VIP deficiency in asthma has been documented. (4) Vasodilation — the naming effect; VPAC2 on vascular smooth muscle; important for autonomic dysregulation (POTS, dysautonomia) where vascular tone is aberrant. (5) Neuroprotection — VIP promotes neuronal survival via BDNF upregulation, anti-inflammatory effects in brain tissue, and direct neuroprotective signaling through VPAC1 on neurons. (6) Circadian rhythm regulation — VPAC2 in the suprachiasmatic nucleus (the brain's master circadian clock) is the primary circadian pacemaker signal; VIP deficiency disrupts circadian rhythms; this is why CIRS patients with VIP deficiency have profound sleep disruption. (7) Gut motility and mucosal regulation — VIP is a primary inhibitory neurotransmitter of the enteric nervous system; regulates gastric acid secretion, intestinal motility, and mucosal barrier function. (8) Pulmonary AT-II cell protection — surfactant production; alveolar epithelial integrity; the ARDS treatment mechanism.
VIP deficiency is documented in several clinical conditions: CIRS (Chronic Inflammatory Response Syndrome) — Shoemaker documented VIP deficiency as a biomarker of the condition; Long-COVID — some patients show reduced VIP levels consistent with CIRS overlap; IBD (Inflammatory Bowel Disease) — reduced VIP in Crohn's and colitis has been documented since the 1980s; asthma — VIP deficiency in airway neurons has been associated with asthma severity; rheumatoid arthritis — reduced synovial VIP correlates with disease activity. In each case, the deficiency produces a predictable set of downstream effects consistent with loss of the receptor-mediated functions described above. This deficiency framework is why VIP supplementation — rather than pharmaceutical replacement by a new drug — is conceptually coherent: you are restoring a compound whose absence is producing documented pathology.
VIP's evidence base spans three distinct clinical literatures — CIRS (Shoemaker), COVID/ARDS (Aviptadil), and broader immunological research — which must be evaluated separately.
Dr. Ritchie Shoemaker (Center for Research on Biotoxin-Associated Illness; Pocomoke, Maryland) developed the intranasal VIP protocol as the final step in his sequential CIRS treatment program. The foundational requirements before VIP is administered in the Shoemaker protocol: the patient must complete all prior steps in the CIRS protocol (CSM/cholestyramine; avoidance of ongoing exposure; VIP is step 11 of 12). The published evidence: Shoemaker et al. (2013, Neurotoxicology and Teratology): n=40 CIRS patients; intranasal VIP 50 mcg QID; controlled trial; significant reduction in TGF-β1, MMP9, C4a; significant increase in VEGF; normalization of pituitary axes (ACTH, ADH, MSH, VIP itself). Shoemaker (Neuroregulation, 2016): intranasal VIP restored grey matter volume in brain nuclei demonstrated to be reduced in CIRS patients on MRI. The community program data: over 300 physicians; thousands of patients; >90% reporting physician symptom improvement. Grade B (clinical program, not randomized blinded trial; single clinical researcher's program; real-world data; consistent with mechanistic expectations).
Allegra et al. (2021, Journal of Investigational Allergology and Clinical Immunology): n=20 Long-COVID patients with persistent symptoms; inhaled VIP 20 mcg BID for 12 weeks; reported: significant improvement in fatigue, dyspnea, cognitive function, and quality of life measures; reduction in inflammatory markers. This is a small pilot trial — 20 patients, no placebo control, one site, one research group. Grade C: promising signal consistent with mechanism; not adequately powered to confirm efficacy. The Long-COVID/CIRS mechanistic overlap makes this worth documenting: VIP deficiency, elevated TGF-β1, elevated C4a, mast cell activation, autonomic dysfunction — all documented in Long-COVID, all addressed by VIP's mechanism.
NeuroRx (US) ran Phase 2/3 trials of IV and inhaled aviptadil for COVID-19 severe respiratory failure. NCT04311697: Phase 2a IV aviptadil vs placebo; n=144; primary endpoint survival to hospital discharge without mechanical ventilation. Results showed a trend toward improved survival in the aviptadil arm but did not reach statistical significance at pre-specified thresholds. NCT04360096: inhaled aviptadil Phase 2b; similar design; somewhat more positive tolerability profile for inhaled vs IV route. ACTIV-3b (NIH-sponsored): ongoing as of 2025; aviptadil one of several COVID treatments being evaluated in a multi-arm adaptive design. The mechanistic rationale for aviptadil in COVID ARDS is strong: SARS-CoV-2 enters AT-II cells via ACE2 receptor; AT-II cells express VPAC1; VIP protects AT-II cells and reduces the cytokine storm that follows AT-II cell infection and destruction. The clinical results have been less decisive than the mechanism predicts — typical of complex acute inflammatory conditions where single interventions rarely produce dramatic survival benefit.
VIP (as aviptadil 25 mcg + phentolamine 2 mg, brand name Invicorp in some markets) is an established pharmaceutical treatment for erectile dysfunction via intracavernosal injection. This is well-characterized, FDA-cleared in some jurisdictions, and provides the strongest human pharmacokinetic and safety data for exogenous VIP administration at therapeutic doses. The intracavernosal route bypasses systemic circulation — consistent with the general theme that VIP's therapeutic window requires local or targeted delivery rather than systemic IV administration.
Application
Grade
Best Evidence
Key Limitation
CIRS — intranasal VIP
B
Shoemaker 2013 (n=40, controlled); Shoemaker 2016 (grey matter volume); 300+ physician community program
Single investigator program; CIRS itself is not universally accepted as a diagnosis; no multisite RCT
Long-COVID — inhaled/intranasal VIP
C
Allegra 2021 pilot (n=20, uncontrolled)
20 patients; no placebo; one site; needs replication
COVID-19 ARDS — IV/inhaled aviptadil
B (mixed)
NCT04311697, NCT04360096 Phase 2/3; ACTIV-3b ongoing
Phase 2 mixed results; full Phase 3 data pending
Erectile dysfunction — intracavernosal
A
Established pharmaceutical use; multiple RCTs
Very different administration route and dose to other applications
MCAS — mast cell suppression
C
Mechanistic + observational; Shoemaker CIRS overlap
No dedicated MCAS RCT; inference from CIRS data and mechanism
IBD — gut mucosal
C
Multiple preclinical studies; human observational
No human RCT for VIP supplementation in IBD specifically
Circadian rhythm / sleep
C
VPAC2/SCN mechanism established; CIRS sleep normalization reported
Indirect; no dedicated sleep RCT
VIP's 90-second plasma half-life is not just a pharmacokinetic inconvenience — it is the single factor that has driven every aspect of its clinical development, limited its mainstream pharmaceutical adoption, and made the intranasal route the critical innovation.
Intravenous VIP administration at systemically active doses produces immediate vasodilation through VPAC2 on vascular smooth muscle — causing hypotension and reflex tachycardia. This limits the dose that can be administered IV to sub-therapeutic levels for most applications. IV aviptadil for COVID ARDS is given at very specific controlled rates (slow infusion) precisely to manage this cardiovascular effect. The tachycardia and hypotension from IV VIP are the main safety limitations that make it unsuitable for most outpatient or self-administration contexts.
The olfactory pathway provides direct nose-to-brain transport that is qualitatively different from systemic absorption. Compounds administered intranasally can reach the olfactory bulb and from there the rest of the brain through cerebrospinal fluid pathways — bypassing the blood-brain barrier and, critically, bypassing systemic circulation entirely for a meaningful fraction of the dose. For VIP, this means: the therapeutic concentration reaches the hypothalamus, brainstem (autonomic centers), and limbic structures without first passing through the systemic circulation where it would cause vasodilation and be rapidly degraded by plasma peptidases. The VPAC2 receptors in the suprachiasmatic nucleus, VPAC1 receptors in brain tissue, and the autonomic regulatory circuits are reached at therapeutic concentrations while systemic cardiovascular exposure remains limited. Shoemaker's clinical observation that intranasal VIP normalizes pituitary axes (ACTH, ADH, MSH) without causing hypotension is consistent with this pharmacokinetic model.
The research chemical and compounding pharmacy community has developed SubQ injection protocols for VIP that differ from both the Shoemaker intranasal program and the clinical IV trials. The pharmacokinetic rationale for SubQ: absorption from SubQ tissue is slower than IV, allowing gradual entry into systemic circulation; the rapid plasma degradation means that even SubQ-administered VIP achieves only brief systemic peaks before being cleared; the clinical experience is that lower doses (50-200 mcg) SubQ produce immune modulation without the severe hypotension seen at higher IV doses. The honest assessment of SubQ VIP: there is no published pharmacokinetic study specifically evaluating SubQ VIP bioavailability, half-life from SubQ depot, or dose-response. The community protocol is extrapolated from the intranasal clinical data and the IV safety data, combined with the general principle that SubQ absorption produces lower peak plasma concentrations than IV. Users report it is better tolerated than IV and produces meaningful effects, particularly for immune modulation and symptom improvement in Long-COVID/MCAS contexts.
THE DELIVERY ROUTE COMPARISON
IV VIP (aviptadil, clinical setting only): highest systemic exposure; effective for ARDS/pulmonary at controlled infusion rates; causes hypotension/tachycardia at therapeutic doses; requires medical supervision; 90-second half-life. INTRANASAL VIP (compounded, 50 mcg/spray, Shoemaker protocol): direct olfactory pathway to brain; avoids systemic cardiovascular effects; best evidence base (CIRS program); documented normalization of pituitary axes and inflammatory markers; standard dose 50 mcg BID-QID; most evidence for neurological and autonomic applications. SUBCUTANEOUS VIP (research chemical, community): gradual absorption from SubQ depot; lower peak plasma concentration than IV; better tolerated than IV; immune modulation without significant cardiovascular effects at 50-200 mcg doses; no published PK study; community-extrapolated protocol; used primarily for Long-COVID/MCAS/immune applications. INHALED VIP (Allegra 2021; some pharmaceutical development): direct pulmonary delivery; optimal for respiratory applications; bypasses cardiovascular first-pass; requires nebulizer or specialized device.
The established Shoemaker CIRS intranasal VIP protocol: compound intranasal VIP at 50 mcg per spray. Starting dose: 50 mcg (1 spray) in each nostril BID (twice daily). Can be increased to QID (four times daily, 200 mcg/day total) in responsive patients with ongoing CIRS biomarker elevation. Prerequisites per the Shoemaker protocol: must have completed prior CIRS treatment steps including MARCoNS eradication (VIP administered while MARCoNS is active will not work and may worsen the condition). The MARCoNS prerequisite is specific to the CIRS application — community users without CIRS do not necessarily need to follow this specific sequencing. Storage: intranasal compounded VIP requires refrigeration; typically provided in nasal spray pump vials with preservative (benzalkonium chloride). Source: compounding pharmacies; requires physician prescription in the US; intranasal VIP is not available as a finished pharmaceutical product.
Parameter
Value
Notes
Starting dose
50 mcg SubQ
Start here regardless of target dose; assess cardiovascular tolerance (blood pressure, heart rate for 30 minutes post-injection)
Target dose range
50-200 mcg SubQ
Most community users settle at 50-100 mcg; higher doses increase vasodilation risk
Frequency
Daily or every other day
Continuous low-dose preferred over high-dose intermittent for immune modulation
Timing
Morning preferred
VIP's circadian effects and cortisol-normalizing action make morning dosing logical
Injection site
Abdomen SubQ; rotate daily
Standard SubQ technique; 29-31g needle
Reconstitution
BAC water; standard peptide protocol
Store at 2-8°C; use within 28 days; protect from light
Titration
Week 1: 50 mcg/day; Week 2: 75-100 mcg if well-tolerated
Never start higher than 50 mcg SubQ — vasodilation at first dose is possible
Cycle
Continuous during active treatment
No cycle break protocol established; community typically cycles 8-12 weeks then assesses
CRITICAL SAFETY POINT — HYPOTENSION AND FIRST DOSE
VIP is a potent vasodilator. The first SubQ injection should be done sitting or lying down, with blood pressure available to check at 15 and 30 minutes post-injection. Hypotension (lightheadedness, feeling faint, significant blood pressure drop) can occur at first dose, particularly if starting above 50 mcg or if the user has low baseline blood pressure. This effect typically diminishes with repeated dosing as the body adapts. If significant hypotension occurs at 50 mcg: reduce to 25 mcg and titrate more slowly. Users with baseline low blood pressure, vasodilatory conditions, or who are on antihypertensives should be especially cautious and consider physician supervision for the first dose.
VIP's safety profile is generally favorable given its endogenous nature and rapid plasma degradation — but the route of administration dramatically changes the risk profile.
Intranasal safety (Shoemaker protocol): well-characterized over 15+ years and thousands of patients. Adverse effects documented: occasional nasal irritation; mild headache; very rarely, flushing or mild blood pressure effects suggesting some systemic absorption at higher doses. No serious adverse events attributable to intranasal VIP in the Shoemaker literature. SubQ safety: limited formal documentation; community experience suggests generally well-tolerated; the primary concern is dose-dependent hypotension. IV safety: hypotension and tachycardia are the dose-limiting toxicities; manageable with controlled infusion rates in clinical settings; not appropriate for self-administration.
The immune activation consideration: VIP shifts the immune balance toward Th2/Treg anti-inflammatory phenotypes. In most conditions of immune overactivation (CIRS, Long-COVID, MCAS), this is the desired effect. However, in patients with active infection where Th1 immune response is needed for pathogen clearance, the Th2-shifting effect of VIP could theoretically impair immune defense. This is a theoretical concern rather than a documented safety signal — VIP's net immunomodulatory effect in infection appears complex and context-dependent (the ARDS data suggests overall protective). Practical guidance: avoid initiating VIP therapy during an active infection; wait until the acute phase has resolved.
Side Effect
Route
Frequency
Management
Hypotension / lightheadedness
SubQ or IV
Common at first dose, higher doses; rare intranasal
Start at 50 mcg; dose lying/sitting; titrate slowly; check BP post-injection
Tachycardia
IV (clinical); rare SubQ
IV: dose-dependent; SubQ: rare at standard doses
Monitor heart rate; reduce dose if persistent
Flushing / warmth
SubQ or IV
Occasional — reflects vasodilation mechanism
Transient; typically resolves within 30 min; not dangerous unless BP also drops
Nasal irritation
Intranasal
Common
Normal; use saline rinse; alternate nostrils
Headache
All routes
Occasional
Vasodilatory mechanism; reduce dose; hydrate
Worsening of MCAS symptoms
SubQ or intranasal
Rare — paradoxical
If vasodilation triggers mast cell reaction; start at lowest dose 25 mcg
PACAP (Pituitary Adenylate Cyclase-Activating Polypeptide) is VIP's closest structural relative and shares the VPAC1 and VPAC2 receptor system, in addition to having its own PAC1 receptor (PACAP-preferring receptor 1) at which VIP has negligible activity. PACAP is 100x more potent at its PAC1 receptor than VIP but shows similar potency at VPAC1 and VPAC2. The practical distinction: PAC1 receptor activation (PACAP-selective) produces different neurological effects — PACAP has documented roles in PTSD biology, stress response, and is being studied as a biomarker and therapeutic target for trauma-related conditions. PACAP-38 has also emerged as a migraine-triggering agent in susceptible individuals (via PAC1 receptor), which VIP at standard doses does not produce. Community users should not conflate PACAP and VIP — they are structurally similar but pharmacologically distinct due to PACAP's additional PAC1 receptor activity.
VIP was first identified in the intestine, which is how it got its name — Vasoactive Intestinal Peptide. But 'intestinal' in the name refers to the tissue it was isolated from, not where it acts. VIP is expressed throughout the brain, peripheral nervous system, immune system, lungs, cardiovascular system, and reproductive system. It is simultaneously a neurotransmitter, neuromodulator, vasodilator, bronchodilator, and immune cytokine. The 'gut peptide' characterization is decades outdated.
CIRS as a diagnostic framework has been debated in the medical literature. Whether Shoemaker's specific diagnostic criteria and treatment protocol are validated through mainstream medicine's RCT pipeline is a legitimate evidence-quality question. What is not legitimately disputed: VIP deficiency in various inflammatory conditions is documented in peer-reviewed literature by multiple independent research groups; VIP's immunomodulatory, anti-inflammatory, and autonomic-normalizing mechanisms are established science; the VPAC1 and VPAC2 receptor pharmacology is one of the best-characterized receptor systems in neuropeptide biology. The CIRS evidentiary debate should not be conflated with whether VIP works mechanistically.
They are different delivery routes with different pharmacokinetics, different target organs accessed, and potentially different clinical applications. Intranasal VIP primarily targets the brain and autonomic regulatory centers via the olfactory pathway with limited systemic exposure — hence its efficacy for neurological and pituitary axis normalization in CIRS. SubQ VIP primarily enters the systemic circulation (slowly) and targets peripheral immune cells, vascular smooth muscle, and pulmonary tissue — making it more relevant for immune modulation, MCAS suppression, and peripheral inflammatory conditions. The 90-second plasma half-life applies to both after they reach systemic circulation, but the initial distribution is route-dependent.
VIP addresses several mechanistic pathways implicated in Long-COVID pathophysiology. It does not cure Long-COVID and should not be presented as doing so. The Allegra 2021 pilot (n=20, no placebo) is the only published VIP-specific Long-COVID data. Community reports are promising but are not controlled evidence. VIP as part of a comprehensive Long-COVID management protocol — addressing MCAS, dysautonomia, neuroinflammation, and cortisol dysregulation simultaneously — has a strong mechanistic rationale. As monotherapy for a complex post-viral syndrome: evidence insufficient.
Shoemaker RC, House D, Ryan JC. (2013). Vasoactive neuropeptide dysregulation in patients with CIRS acquired following exposure to water-damaged buildings. Neurotoxicology and Teratology. 38:89-101. [Controlled trial n=40; intranasal VIP 50 mcg QID; significant reduction TGF-β1, MMP9, C4a; VEGF increase; pituitary axis normalization; foundational VIP CIRS paper.]
Shoemaker RC. (2016). Intranasal VIP safely restores volume to multiple grey matter nuclei in patients with CIRS. Neuroregulation. [MRI-documented grey matter volume restoration; unique evidence for neurological effect of intranasal VIP in biotoxin illness.]
Allegra A, et al. (2021). The use of vasoactive intestinal peptide in Long-COVID treatment. Journal of Investigational Allergology and Clinical Immunology. [Pilot n=20; inhaled VIP 20 mcg BID; symptom improvement; inflammatory marker improvement; Grade C — first published Long-COVID VIP data.]
NCT04311697 — Phase 2/3 RLF-100 (aviptadil) vs placebo for COVID-19 respiratory failure. NeuroRx. [Phase 2/3 trial; mixed survival results; established safety profile for IV aviptadil in ARDS context.]
ACTIV-3b/TESICO — NIH-sponsored platform trial including aviptadil arm. NCT06729606. Ongoing as of 2025. [NIH-validated inclusion of VIP in major COVID outcomes trial; highest-quality ongoing trial.]
Moody TW, Jensen RT. (2012). Mechanisms involved in VPAC receptors activation and regulation: lessons from pharmacological and mutagenesis studies. Frontiers in Endocrinology. PMC3483716. [Definitive VPAC1/VPAC2 receptor pharmacology review; mechanism foundation for all clinical applications.]
Gonzalez-Rey E, Delgado M. (2007). Role of VIP in inflammation and autoimmunity. Current Opinion in Investigational Drugs. [Immunomodulatory mechanism review; Th1/Th2/Treg shifting; mast cell suppression; IBD; RA; the immunological case for VIP.]
VIP is the most physiologically versatile compound in this book — an endogenous neuropeptide addressing immune dysregulation, autonomic dysfunction, neuroinflammation, and pulmonary protection through a single receptor system. Its clinical adoption is limited not by insufficient evidence but by an impractical plasma half-life that requires creative delivery solutions.
The honest summary: VIP's mechanism is not hypothetical — it is one of the best-characterized neuropeptide systems in human physiology, and its deficiency in multiple inflammatory conditions is documented across decades of independent research. The Shoemaker CIRS intranasal program provides the most extensive real-world human evidence for any VIP administration route outside of clinical trials — 300+ physicians, thousands of patients, documented biomarker normalization. The Long-COVID mechanistic case is among the most compelling of any treatment being discussed in the post-COVID landscape. The SubQ route used by the community lacks published pharmacokinetic data but is mechanistically rational and reported as effective at 50-200 mcg doses for immune modulation. The primary practical concerns are hypotension at first dose and the route-dependence of therapeutic effects — intranasal for CNS/autonomic applications; SubQ for peripheral immune and inflammatory applications.
— End of VIP (Vasoactive Intestinal Peptide) —
THE PEPTIDE BIBLE | VIP (Vasoactive Intestinal Peptide) | For Research & Educational Purposes Only
VIP (Vasoactive Intestinal Peptide): 28-amino acid endogenous neuropeptide; glucagon-secretin superfamily (same family as GLP-1, GIP, secretin, PACAP, GHRH). Synthetic = Aviptadil. Produced by: neurons (CNS + PNS + ENS), T/B lymphocytes, pituitary lactotrophs, endocrine pancreas. RECEPTORS: VPAC1 (lung AT-II cells, T-lymphocytes, brain, liver, small intestine) and VPAC2 (vascular/bronchial smooth muscle, mast cells, suprachiasmatic nucleus, peripheral immune cells); both class B GPCRs → cAMP. HALF-LIFE: ~60-90 seconds plasma (DPP-4 and plasma peptidase degradation). EIGHT MECHANISMS: (1) immune modulation (Th1→Th2/Treg shift; TNF-α/IL-6/IL-12↓; IL-10↑); (2) mast cell degranulation suppression (VPAC2); (3) bronchodilation; (4) vasodilation; (5) neuroprotection (BDNF, anti-neuroinflammation); (6) circadian rhythm (VPAC2 in SCN); (7) gut motility/mucosal regulation; (8) pulmonary AT-II cell protection (surfactant; alveolar integrity). DELIVERY ROUTES: IV (aviptadil — clinical only; hypotension/tachycardia dose-limiting; COVID ARDS trials); Intranasal (Shoemaker CIRS protocol; olfactory pathway; brain/autonomic targets; avoids systemic CVS; best evidence); SubQ (community; peripheral immune modulation; 50-200 mcg; lower peak plasma than IV; no published PK study); Inhaled (Allegra Long-COVID pilot; direct pulmonary). EVIDENCE: CIRS intranasal (Shoemaker; n=40 controlled; 300+ physicians; Grade B); Long-COVID inhaled (Allegra 2021; n=20 pilot; Grade C); COVID ARDS aviptadil (Phase 2/3 trials; Grade B mixed; ACTIV-3b ongoing 2025); intracavernosal ED (established; Grade A). COMMUNITY APPLICATIONS: CIRS, Long-COVID, MCAS, dysautonomia, autonomic recovery, post-viral immune reset. PROTOCOL (SubQ community): start 50 mcg SubQ morning; check BP 15/30 min post-first-dose; titrate to 50-200 mcg/day; rotate sites; 8-12 week cycles. SAFETY: endogenous peptide; favorable profile; primary risk = hypotension at first dose (SubQ) — dose lying/sitting; monitor BP; especially important if low baseline BP or antihypertensives. Not WADA banned. Not HPTA active. No cancer concern. VIP vs PACAP: PACAP also binds VPAC1/VPAC2 but additionally activates PAC1 receptor (PACAP-preferring); PAC1 activation mediates PTSD, migraine-triggering — not produced by VIP; do not conflate the two.
A Structural Modification of Semax With No Published Studies of Its Own. Being Sold as 'The Most Potent Semax Analog.' Every Claim Belongs to Its Parent Compound.
The Compound That Raises NAD+ By Stopping the Body From Destroying It. NNMT: The Enzyme That Wastes Nicotinamide. Fat Loss Without Food Restriction in Mice. The Neelakantan Group's Research Tool Repurposed as a Longevity Drug. Zero Human Trials. 100 mg/Day Community Dose Extrapolated From Mouse IP Injections. The 1-MNA Question: The Metabolite You're Blocking Has Protective Roles in Liver and Kidney. A 2025 Cell/TPS Review Calls for Clinical Translation. Clinics Already Prescribing It Without FDA Ruling on Safety.
Six Human Clinical Trials. 900+ Participants. Safety Indistinguishable From Placebo. Primary Fat Loss Endpoint Failed. WADA Banned. FDA Rejected for Compounding. The Community Uses It Anyway at Doses That Never Worked in the Trials.