History

VIP is a 28-amino-acid neuropeptide first characterized as a potent vasodilator isolated from intestinal tissue, later found throughout the gut, lungs, central nervous system, and autonomic nerves. It signals through the class-B G-protein-coupled receptors VPAC1 and VPAC2 to relax smooth muscle and dampen inflammation. The synthetic form, aviptadil (developed as ZYESAMI / RLF-100 by NRx Pharmaceuticals and Relief Therapeutics), drew major attention during the COVID-19 pandemic for respiratory failure. It holds FDA orphan-drug designations for ARDS (2001) and pulmonary arterial hypertension (2005) and a Fast Track designation (June 2020) — but the FDA twice declined emergency use authorization, and the definitive randomized trial was negative.

VIP (vasoactive intestinal peptide) is a genuine human signalling molecule with real, but disappointing, human research behind it. Despite years of high-profile development as the drug aviptadil, no VIP product is FDA-approved for any indication, and the largest rigorous trial of VIP for a serious condition was negative. The version that circulates in biohacking and “mold illness” circles — an intranasal spray for chronic inflammation and brain recovery — is an even less proven story built largely on a single investigator’s uncontrolled reports.

What it is

VIP is a 28-amino-acid neuropeptide of the secretin/glucagon superfamily, widely distributed in the gut, lungs, central nervous system, and peripheral and autonomic nerves. It is a potent vasodilator and smooth-muscle relaxant with prominent anti-inflammatory and immune-regulating activity. It acts mainly on two class-B G-protein-coupled receptors, VPAC1 and VPAC2 (and also binds PACAP receptors); these are Gs-coupled, so activation raises intracellular cAMP and drives PKA/CREB signalling. VPAC1 predominates on immune cells (T cells, macrophages) and in the lung, while VPAC2 is enriched in the suprachiasmatic nucleus, smooth muscle, and enteric neurons. The documented downstream effects include vasodilation, bronchodilation, pulmonary surfactant-related effects, and a shift in cytokine balance toward anti-inflammatory states — it lowers TNF-alpha and other Th1 cytokines and promotes regulatory T-cell phenotypes. Those immune properties are the rationale behind both its study in inflammatory lung disease and the biohacking interest in it. The synthetic version is the drug aviptadil. Native VIP has a very short plasma half-life (roughly one to two minutes), so it has to be given locally — by inhalation, nasally, or topically — or by infusion, rather than as a stable systemic pill.

The claims

In the consumer and CIRS (“chronic inflammatory response syndrome,” the mold/biotoxin-illness framework) space, intranasal VIP is promoted to calm systemic inflammation, restore immune and hormone balance, repair “neuroinflammation,” and even reverse brain-volume loss. The reported normalizations of markers like MMP9, TGF-beta1, C4a, and VEGF are cited as evidence. Adjacent marketing extends to longevity, recovery, cognitive enhancement, and general anti-inflammatory “optimization.” These claims lean heavily on VIP’s plausible mechanism and on a single investigator group’s case reports, and they run well ahead of what controlled human data can support.

What the evidence actually shows

Real human data on VIP exist — more than for many peptides sold online — but the strongest evidence is negative, and the consumer claims are essentially unsupported.

COVID-19 respiratory failure (IV aviptadil) — the reality check: The large, rigorous NIH-sponsored ACTIV-3b/TESICO randomized, placebo-controlled trial is the strongest human dataset, and it was negative. Aviptadil did not meet its primary endpoint — no significant improvement in the day-90 ordinal outcome (odds ratio 1.11, 95% CI 0.80–1.55, p=0.54), and day-90 mortality was 38% with aviptadil versus 36% with placebo (HR 1.04, p=0.78). (Brown et al., Lancet Respir Med, 2023.)
A smaller, more favorable trial — weighed against the big one: A separate sponsor-associated Phase 2/3 RCT (NCT04311697, “ZYESAMI [Aviptadil],” roughly 196 patients analyzed, randomized 2:1) reported more favorable recovery, survival, and oxygenation signals (Youssef et al., Crit Care Med, 2022). But it is smaller, sponsor-linked, and was not sufficient for FDA authorization — it has to be weighed against the larger, definitive, negative TESICO result.
ARDS meta-analysis (2025): A systematic review and meta-analysis of aviptadil in ARDS concluded it is not significantly associated with improved survival, with limited and inconclusive overall evidence and a call for larger RCTs (Udupa et al., Indian J Crit Care Med, 2025).
Sarcoidosis (inhaled VIP): A real open-label phase II study of 20 patients (no placebo) treated with nebulized VIP found it safe and well tolerated, with reduced TNF-alpha production by bronchoalveolar-lavage cells and an increase in regulatory T cells (Prasse et al., 2010). That is a genuine immunologic signal — but it is small, uncontrolled, measured surrogate (lab) endpoints, and was not powered for clinical outcomes.
Pulmonary hypertension and healthy-subject physiology: Inhaled VIP produced acute reductions in pulmonary vascular resistance in small studies — short-term physiology, not durable clinical-outcome evidence. In healthy volunteers, VIP infusion causes dose-dependent vasodilation and hypotension with reflex tachycardia (Frase et al., Am J Cardiol, 1987), confirming its pharmacology rather than any therapeutic benefit.
CIRS / neuroinflammation / “brain recovery” (the biohacking claim): This is the weakest part of the record. The supporting literature comes almost entirely from one investigator group (Shoemaker), published in non-PubMed-indexed journals (e.g., Internal Medicine Review), with no randomized or placebo-controlled replication and no independent confirmation. The reported MMP9/TGF-beta1/C4a/VEGF normalizations come from the same uncontrolled framework. Treat CIRS-VIP efficacy as thin, low-quality, and essentially unproven.
Longevity, nootropic, performance, cosmetic, recovery uses: No credible human efficacy evidence. The marketing here is extrapolated from mechanism and animal/cell work, not clinical trials.

The honest net: the strongest human evidence — IV aviptadil in COVID respiratory failure — is negative. Sarcoidosis shows a real but tiny, uncontrolled surrogate signal. The CIRS, neuro, recovery, and longevity uses that drive consumer interest are not backed by reliable controlled human data.

Legal and regulatory status

No VIP product is FDA-approved for any indication. The synthetic VIP drug aviptadil (ZYESAMI / RLF-100; NRx Pharmaceuticals and Relief Therapeutics) is investigational, and the FDA declined emergency use authorization twice for critical COVID-19 — in November 2021 (citing insufficient benefit/risk data, with safety reviewed in only 131 randomized patients) and again in July 2022 (a post-hoc subgroup request; the FDA had also declined Breakthrough Therapy Designation). Aviptadil does hold FDA orphan-drug designations — for ARDS (granted 2001) and pulmonary arterial hypertension (granted 2005) — and a Fast Track designation (granted June 2020 for COVID-19 respiratory distress). These are designations, not approvals, and confer no efficacy verdict.

Intranasal VIP used in CIRS protocols is a compounded, off-label preparation, not an FDA-approved drug; its supporting publications appear in non-indexed journals, a meaningful evidence-quality caveat. (Whether VIP currently sits on the FDA’s 503A “bulk drug substance” list for compounding is something a reader should confirm directly against the live FDA list rather than take on faith — it is not settled here.) “Research peptide” VIP sold by vendors for biohacking, longevity, or recovery is research-grade material, not a medicine: unapproved for human use and not pharmacy-quality assured.

A note on a common point of confusion: desmopressin (DDAVP) is an FDA-approved peptide drug, but it is an analog of vasopressin/ADH — a different peptide — and is not VIP-related, so its approval says nothing about VIP. (Desmopressin is itself WADA-prohibited as a masking agent, a separate regulatory track entirely.)

For athletes: VIP/aviptadil is not named as a specific example on the WADA Prohibited List (including the 2026 list, in force since 1 January 2026). However, S2 (“Peptide Hormones, Growth Factors, Related Substances and Mimetics”) uses open, catch-all language, and VIP is a vasoactive peptide hormone — so athletes should not assume it is permitted. This is an inference from S2’s catch-all framing, not an explicit listing (distinct from clearly listed classes such as SARMs under S1 or metabolic modulators like AICAR under S4). Confirm specific status with your anti-doping authority or through the TUE process rather than assuming it is allowed.

Safety

VIP’s predictable pharmacology produces dose-dependent effects you would expect from a potent vasodilator: hypotension, facial flushing, headache, reflex tachycardia, and diarrhea or other GI effects. IV use requires hemodynamic monitoring. In the COVID/ARDS trials and the sarcoidosis study, inhaled or IV aviptadil was generally described as tolerated, without a clear excess of serious drug-related events — but tolerability is not efficacy, and the large definitive trial still failed.

For the biohacking route, the honest caveats matter. Intranasal, compounded, and research-grade VIP comes with no rigorous long-term safety dataset, and product quality — purity, sterility, dosing accuracy — is not assured for non-pharmaceutical material, a real concern for nasal or injectable use. Favorable “no significant side effects” claims in CIRS reports come from small, uncontrolled, single-group case series and should be read with skepticism. Vasodilatory hypotension is a genuine hazard, especially when combined with other vasodilators or in someone dehydrated. The bottom line on safety: short-term tolerability looks acceptable in monitored clinical settings, but for unapproved biohacking, longevity, or cosmetic use the real risk is unproven benefit plus an unregulated product, not a single dramatic toxicity. None of this is medical advice.

Bottom line

VIP is a real human neuropeptide with genuine anti-inflammatory biology, but its development record is sobering: no approved product anywhere, two FDA refusals to authorize aviptadil for COVID-19, and a definitive randomized trial that came up negative. Sarcoidosis offers a small, uncontrolled surrogate-endpoint signal, and the intranasal “CIRS / brain recovery” use that drives most online interest rests almost entirely on a single research group’s uncontrolled reports in low-quality venues. Plausible mechanism is not proof, and orphan and fast-track designations are paperwork, not evidence of benefit.

Evidence grade: Preliminary human. (Real human trials exist, but the strongest controlled data are negative and no use is approved; the consumer CIRS, nootropic, longevity, and recovery claims have no credible human evidence.)

VIP (Vasoactive Intestinal Peptide)