Vasoactive intestinal peptide, or VIP, is a naturally occurring 28-amino-acid neuropeptide produced throughout the body, with roles in dilating blood vessels, modulating immune activity, and signaling between the gut and the nervous system. It's also the compound at the center of a specific wellness claim worth examining carefully: that a compounded VIP nasal spray can resolve "mold illness," more formally called chronic inflammatory response syndrome (CIRS).
What CIRS Protocols Claim
CIRS, as described by the functional-medicine physicians who popularized the term, is proposed to result from ongoing exposure to biotoxins — most often attributed to water-damaged buildings and mold — producing a cluster of symptoms including fatigue, brain fog, joint pain, and respiratory issues in susceptible individuals. The treatment protocol built around this framework is sequential: removing the patient from exposure, using binders to reduce biotoxin absorption, and finally, as a capstone step, prescribing compounded VIP nasal spray, often described to patients as addressing lingering inflammation and hormonal dysregulation that earlier steps didn't fully resolve.
CIRS itself is not a diagnosis recognized by mainstream allergy, immunology, or infectious disease societies, and no large, independent, peer-reviewed clinical trials have tested compounded VIP nasal spray specifically for mold-related symptoms. Most of what's published in support of this specific use comes from the practitioners who developed the protocol, rather than from independent researchers replicating the finding — an important distinction when weighing how much confidence to place in a treatment claim.
VIP Does Have Real Clinical Research — In Different Conditions
This is where the picture gets more nuanced than a simple "it's fake" dismissal. VIP, under the investigational drug name aviptadil, has gone through actual registered human clinical trials for unrelated conditions, including pulmonary arterial hypertension and sarcoidosis, and it was tested in multiple trials as a potential treatment for severe COVID-19 respiratory failure during the pandemic — trials that ultimately did not demonstrate a clear survival benefit in that setting. That track record matters for two reasons: it shows VIP is a biologically active molecule capable of being studied in rigorous human trials, and it shows that even in indications backed by real trial infrastructure, VIP-based treatment hasn't produced a slam-dunk result. Neither of those trial programs addressed CIRS or mold-related illness, so they can't be used as evidence that compounded VIP nasal spray helps with that specific claim.
Regulatory Status
No VIP-based drug product is FDA-approved for CIRS, mold-related illness, or general wellness use. Compounded VIP nasal spray sold for this purpose is prepared by compounding pharmacies under a physician's prescription, which means it has not gone through FDA review for safety or effectiveness in this specific use, and supply, purity, and dosing consistency depend on the individual pharmacy rather than standardized manufacturing.
What This Means If You've Been Told You Have "Mold Illness"
Symptoms attributed to CIRS — fatigue, brain fog, joint pain — are real and worth taking seriously, but they also overlap heavily with many other conditions that do have established diagnostic criteria and treatments, from thyroid disorders to sleep apnea to depression. Before starting a VIP protocol, it's worth getting a second opinion from a physician outside the functional-medicine framework that developed the CIRS diagnosis, specifically to rule out better-understood causes of the same symptoms. If VIP nasal spray is still being considered afterward, ask directly what independent, peer-reviewed human evidence exists for that specific use — not evidence for VIP in general, and not testimonials.