VIP (Vasoactive Intestinal Peptide)

VIP (vasoactive intestinal peptide) is a real signalling molecule your own body makes, and it has genuine — though disappointing — human research behind it. Despite years of high-profile work to turn it into the drug aviptadil, no VIP product is FDA-approved for anything, and the biggest, most carefully run trial of VIP for a serious illness came up empty. The version that gets passed around in biohacking and “mold illness” circles — a nasal spray aimed at calming inflammation and healing the brain — is an even shakier story, built mostly on the uncontrolled reports of a single researcher.

What it is

VIP is a small protein-like molecule (a neuropeptide built from 28 amino acids, the building blocks of proteins). It belongs to the secretin/glucagon family and shows up all over the body — in the gut, the lungs, the brain and spinal cord (the central nervous system), and the nerves that run the rest of the body. It is a strong vasodilator (it widens blood vessels) and relaxes smooth muscle, and it has notable anti-inflammatory and immune-calming effects.

It works mainly by latching onto two receptors called VPAC1 and VPAC2 (it also binds a related receptor type, PACAP). When VIP activates these receptors, it raises a cell’s level of a messenger molecule called cAMP, which switches on a chain of internal signals (the PKA/CREB pathway). VPAC1 is the main version found on immune cells (such as T cells and macrophages, two kinds of white blood cell) and in the lung. VPAC2 is more common in a brain region that runs the body clock (the suprachiasmatic nucleus), in smooth muscle, and in the nerves of the gut.

The effects that have actually been documented include widening blood vessels, opening the airways (bronchodilation), helping with the lung’s natural coating that keeps air sacs open (surfactant), and nudging the immune system toward a calmer, less inflammatory state. In plain terms, it lowers TNF-alpha and other “fire-up” immune signals (Th1 cytokines) and encourages calming regulatory T cells. Those immune effects are exactly why researchers studied it in inflammatory lung disease — and why biohackers got interested too. The lab-made version is the drug aviptadil. One catch: natural VIP breaks down in the blood within about one to two minutes, so it can’t be taken as a stable everyday pill. It has to be delivered right where it’s needed — breathed in, sprayed in the nose, applied to the skin — or given as a slow drip into a vein (infusion).

The claims

In the consumer and CIRS world — CIRS stands for “chronic inflammatory response syndrome,” the framework that blames lingering illness on mold and other biotoxins — nasal-spray VIP is sold as a way to quiet body-wide inflammation, rebalance the immune and hormone systems, repair “neuroinflammation” (inflammation in the brain), and even reverse shrinkage of brain tissue. Supporters point to reported improvements in lab markers with names like MMP9, TGF-beta1, C4a, and VEGF as proof. The marketing spills over into anti-aging, faster recovery, sharper thinking, and general anti-inflammatory “optimization.” These claims lean hard on VIP’s believable biology and on the case reports of one research group — and they run far ahead of what well-controlled human studies can actually back up.

What the evidence actually shows

There is real human data on VIP — 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, carefully run NIH-sponsored ACTIV-3b/TESICO trial is the best human evidence we have. It was randomized and placebo-controlled (patients were assigned by chance to the drug or a dummy treatment, the gold standard for fairness), and it failed. Aviptadil did not hit its main goal — there was no meaningful improvement on the day-90 outcome scale (odds ratio 1.11, 95% CI 0.80–1.55, p=0.54), and by day 90, 38% of the aviptadil group had died versus 36% on 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-linked Phase 2/3 randomized trial (NCT04311697, “ZYESAMI [Aviptadil],” about 196 patients analyzed, assigned 2:1) reported better recovery, survival, and oxygen signals (Youssef et al., Crit Care Med, 2022). But it was smaller, tied to the company making the drug, and wasn’t enough for the FDA to authorize it — so it has to be weighed against the larger, definitive, negative TESICO result.
• ARDS meta-analysis (2025): A review that pooled the aviptadil studies in ARDS (a severe lung-failure condition) concluded the drug was not clearly linked to better survival, called the overall evidence limited and inconclusive, and asked for bigger trials (Udupa et al., Indian J Crit Care Med, 2025).
• Sarcoidosis (inhaled VIP): A real open-label phase II study (open-label means everyone knew they were getting the drug) in 20 patients, with no placebo group, used nebulized VIP (turned into a fine mist and breathed in). It was safe and well tolerated, and lab tests showed less TNF-alpha made by immune cells washed from the lungs, plus more calming regulatory T cells (Prasse et al., 2010). That’s a genuine immune signal — but the study was small, had no comparison group, measured lab markers (stand-in measures, not how patients actually felt or fared), and wasn’t built to test real-world outcomes.
• Pulmonary hypertension and healthy-subject physiology: In small studies, inhaled VIP briefly lowered pressure in the lung’s blood vessels — a short-term physical effect, not proof of lasting clinical benefit. In healthy volunteers, a VIP infusion caused dose-dependent widening of blood vessels and a drop in blood pressure, with the heart speeding up to compensate (Frase et al., Am J Cardiol, 1987). That confirms how the drug behaves in the body, not that it treats anything.
• CIRS / neuroinflammation / “brain recovery” (the biohacking claim): This is the weakest part of the whole record. Almost all the supporting work comes from a single research group (Shoemaker), published in journals that aren’t indexed in PubMed (for example, Internal Medicine Review), with no randomized or placebo-controlled study to back it up and no independent confirmation from other teams. The reported normalizing of MMP9, TGF-beta1, C4a, and VEGF comes from that same uncontrolled setup. Treat the CIRS-VIP claims as thin, low-quality, and essentially unproven.
• Longevity, nootropic, performance, cosmetic, recovery uses: No credible human evidence that any of these work. The marketing is stretched from VIP’s biology and from animal and cell experiments, not from human trials.

The honest summary: the strongest human evidence — IV aviptadil for COVID respiratory failure — is negative. Sarcoidosis shows a real but tiny, uncontrolled, lab-marker signal. And the CIRS, brain, recovery, and anti-aging uses that drive most of the consumer interest simply aren’t backed by reliable, controlled human studies.

Legal and regulatory status

No VIP product is FDA-approved for any use. The lab-made VIP drug aviptadil (sold as ZYESAMI / RLF-100 by NRx Pharmaceuticals and Relief Therapeutics) is still investigational, and the FDA turned down emergency use authorization twice for critical COVID-19 — first in November 2021 (saying the benefit-versus-risk data wasn’t enough, with safety reviewed in only 131 randomized patients) and again in July 2022 (a request based on looking back at a smaller subgroup; the FDA had also said no to Breakthrough Therapy Designation). Aviptadil does hold a few special FDA labels — orphan-drug designation for ARDS (granted 2001) and for pulmonary arterial hypertension (granted 2005), plus a Fast Track designation (granted June 2020 for COVID-19 respiratory distress). But these are just designations, not approvals; they don’t say the drug works.

The nasal VIP used in CIRS protocols is a compounded, off-label product (mixed by a pharmacy for a use the FDA hasn’t approved), not an approved drug. Its supporting papers run in non-indexed journals, which is a real knock on the quality of the evidence. (Whether VIP is currently on the FDA’s 503A “bulk drug substance” list for compounding is something you should check directly against the live FDA list rather than take on trust — it isn’t settled here.) The “research peptide” VIP that vendors sell for biohacking, longevity, or recovery is research-grade material, not medicine: it isn’t approved for people and isn’t held to pharmacy quality standards.

One common mix-up worth clearing up: desmopressin (DDAVP) is an FDA-approved peptide drug, but it’s a stand-in for vasopressin/ADH — a completely different peptide — and has nothing to do with VIP, so its approval tells you nothing about VIP. (Desmopressin is itself banned by WADA as a masking agent, which is an entirely separate issue.)

For athletes: VIP/aviptadil isn’t named as a specific example on the WADA Prohibited List (including the 2026 list, in effect since 1 January 2026). But section S2 (“Peptide Hormones, Growth Factors, Related Substances and Mimetics”) is written with broad, catch-all wording, and VIP is a vasoactive peptide hormone — so athletes shouldn’t assume it’s allowed. This is a reading of that catch-all language, not an explicit listing (unlike clearly named classes such as SARMs under S1 or metabolic modulators like AICAR under S4). Check the specific status with your anti-doping authority or through the TUE (therapeutic use exemption) process rather than assuming you’re in the clear.

Safety

Because of how VIP works, it causes the kinds of dose-related effects you’d expect from a strong blood-vessel widener: low blood pressure, facial flushing, headache, a faster heartbeat (the body’s reflex to low pressure), and diarrhea or other gut upset. Giving it into a vein requires close monitoring of blood pressure and heart function. In the COVID/ARDS trials and the sarcoidosis study, inhaled or IV aviptadil was generally described as tolerated, with no clear spike in serious drug-related problems — but being tolerated isn’t the same as working, and the big, definitive trial still failed.

For the biohacking route, the caveats really matter. Nasal, compounded, and research-grade VIP comes with no solid long-term safety data, and product quality — how pure, how sterile, how accurately dosed — isn’t guaranteed for non-pharmaceutical material, which is a real worry for anything put up the nose or injected. The reassuring “no real side effects” claims in CIRS reports come from small, uncontrolled, single-group case series and should be read with a healthy dose of skepticism. The blood-pressure drop is a genuine hazard, especially if combined with other vessel-widening substances or if you’re dehydrated. Bottom line on safety: short-term tolerability looks acceptable in monitored medical settings, but for unapproved biohacking, longevity, or cosmetic use, the real risk is an unproven benefit paired with an unregulated product — not one dramatic poisoning. None of this is medical advice.

Bottom line

VIP is a real human neuropeptide with genuine anti-inflammatory biology, but its track record as a drug 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, lab-marker signal, and the nasal-spray “CIRS / brain recovery” use that drives most online interest rests almost entirely on one research group’s uncontrolled reports in low-quality journals. A believable mechanism isn’t proof, and orphan and fast-track labels are paperwork, not evidence that the drug helps.

Evidence grade: 5/10 · Early. (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.)

Sources

• Intravenous aviptadil and remdesivir for COVID-19-associated hypoxaemic respiratory failure (ACTIV-3b/TESICO; Brown et al., Lancet Respir Med, 2023) — PubMed (PMID 37348524)
• ACTIV-3b/TESICO registry record — ClinicalTrials.gov (NCT04843761)
• ZYESAMI (Aviptadil) Phase 2/3 critical-COVID RCT results (Youssef et al., Crit Care Med, 2022) — PMC9555831
• ZYESAMI critical-COVID registry record — ClinicalTrials.gov (NCT04311697)
• Aviptadil in ARDS: systematic review and meta-analysis (Udupa et al., Indian J Crit Care Med, 2025) — PMC12683555
• Inhaled vasoactive intestinal peptide exerts immunoregulatory effects in sarcoidosis (Prasse et al., Am J Respir Crit Care Med, 2010) — PubMed (PMID 20442436)
• Cardiovascular effects of vasoactive intestinal peptide in healthy subjects (Frase et al., Am J Cardiol, 1987) — PubMed (PMID 3687785)
• FDA declines emergency use authorization for ZYESAMI (aviptadil), November 2021 — PR Newswire
• FDA declines emergency use authorization for ZYESAMI (aviptadil) subgroup, July 2022 — PR Newswire
• Aviptadil (mechanism, orphan and fast-track designations, regulatory history) — Wikipedia
• Desmopressin (FDA-approved vasopressin analog; WADA masking agent) — Wikipedia
• WADA Prohibited List — S2 Peptide Hormones, Growth Factors and Related Substances (Drugs.com summary)