Vasoactive intestinal peptide (VIP) is a 28-amino-acid neuropeptide that the body uses to relax blood vessels and smooth muscle, regulate gut secretion, and calm immune responses. It is sometimes called a "master regulator" because its receptors are found in so many tissues, but as a treatment it remains investigational: it is not FDA-approved for any condition, and controlled human trials have not yet shown clear clinical benefit. Its biology is impressive; its therapeutic track record is still being written.
What Is Vasoactive Intestinal Peptide?
VIP was first isolated from pig intestine in 1970, which is how it got its name. Researchers soon found that it is not only a gut hormone. It is also produced by nerves throughout the body and brain, by immune cells, and in the part of the brain that sets the circadian clock.
VIP acts through two receptors, called VPAC1 and VPAC2. Because these receptors appear in blood vessels, the lungs, the digestive tract, the immune system and the nervous system, a single signal can produce a wide range of effects:
- Blood vessels: dilation and lower blood pressure
- Airways: relaxation of smooth muscle (bronchodilation)
- Gut: increased secretion of water and electrolytes, and relaxation of intestinal muscle
- Immune system: reduced production of inflammatory cytokines such as TNF-alpha and IL-6, and support for regulatory T cells that keep immune responses in check
- Brain: a role in circadian rhythm and neuroprotection in laboratory models
A Lesson From VIPoma
The most vivid human evidence of VIP's power comes from a rare tumor. A VIPoma is a pancreatic tumor that overproduces VIP. Patients develop profuse watery diarrhea, low potassium and dehydration — sometimes severe enough to be life-threatening. This is a useful reminder that "natural" signaling molecules are potent. More is not automatically better, and the dose, route and duration matter enormously.
Why VIP Is Called a "Master Regulator"
Much of the excitement about VIP comes from immunology. In laboratory and animal studies, VIP has dampened inflammation in models of arthritis, inflammatory bowel disease, sepsis and autoimmune conditions. Reviews describe it as one of the body's more important anti-inflammatory neuropeptides, linking the nervous and immune systems.
The challenge is translation. VIP has an extremely short half-life in the bloodstream — on the order of minutes — because enzymes break it down rapidly. Its effects on blood vessels can also cause flushing and low blood pressure when it is given systemically. These practical problems have made it difficult to turn VIP's laboratory promise into an effective medicine.
What Human Studies of Vasoactive Intestinal Peptide Show
Severe COVID-19. Aviptadil, a synthetic form of VIP, was studied intravenously in patients with COVID-19-associated respiratory failure. The TESICO trial, a large randomized, placebo-controlled study sponsored by the U.S. National Institutes of Health and published in 2023, did not find that aviptadil improved recovery compared with placebo.
Erectile dysfunction. A combination of aviptadil and phentolamine, injected directly into the penis, has been approved in some European countries. It is not approved in the United States.
Pulmonary and inflammatory conditions. Small studies have explored inhaled VIP for pulmonary hypertension and sarcoidosis, with early, inconsistent results.
Chronic inflammatory response syndrome (CIRS). Some practitioners use intranasal VIP for CIRS, a proposed illness attributed to exposure to mold or other biotoxins. The supporting evidence comes from small, uncontrolled case series, CIRS is not a widely accepted diagnosis in mainstream medicine, and objective benefit has not been established in controlled trials.
Safety Considerations
Because VIP widens blood vessels and increases gut secretion, reported or expected side effects include:
- Flushing and warmth
- Low blood pressure and lightheadedness
- Fast heart rate
- Diarrhea
- Nasal irritation with intranasal use
Caution is warranted in people with low blood pressure, heart rhythm problems, or those taking blood pressure-lowering medications or vasodilators. Data in pregnancy and breastfeeding are lacking. Long-term safety of repeated use has not been studied in rigorous trials.
Regulatory Status
As of this writing, VIP and aviptadil are not FDA-approved for any indication in the United States. Their status for pharmacy compounding has been under FDA review, and the rules governing peptide compounding have been changing in 2024–2026, so check current FDA guidance before assuming any particular product is legal. Whatever the regulatory outcome, buying VIP labeled "for research use only" and self-administering it is unsafe: purity, sterility and dose cannot be verified.
How I Approach Inflammation Concerns
When patients ask about VIP, the underlying concern is usually chronic inflammation, gut symptoms, fatigue or suspected environmental illness. At Laeeq M.D., I start with a thorough internal medicine evaluation: history and exposures, a careful look at gut health, and appropriate labs such as a complete blood count, metabolic panel and inflammatory markers. You can read about those markers in Inflammation Biomarkers: hs-CRP, ESR, and Beyond and about gut-driven inflammation in Gut Health and Systemic Inflammation.
If a treatable cause is found — celiac disease, thyroid disease, sleep apnea, iron deficiency, an autoimmune condition — that comes first. Investigational peptides such as VIP or KPV are discussed only afterward, with a clear account of what is and is not known, and any treatment decision is individualized after evaluation.
Sources
- Vasoactive intestinal peptide: a neuropeptide with pleiotropic immune functions — Delgado M, Ganea D. Amino Acids, 2013
- Intravenous aviptadil and remdesivir for treatment of COVID-19-associated hypoxaemic respiratory failure in the USA (TESICO) — Brown SM, et al. The Lancet Respiratory Medicine, 2023
Book a Consultation
If you are dealing with persistent inflammation, gut symptoms or unexplained fatigue, a structured medical evaluation is the best first step. Dr. Laeeq offers 60-minute consultations, virtually or in person in Reston, VA. Book a consultation to review your history, labs and options.
This article is for educational purposes and is not medical advice. Discuss any treatment with a licensed physician who knows your history.
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Written by Dr. Laeeq Ahmed Butt, M.D., MBA
Board-certified internist practicing peptide and longevity medicine in Reston, VA, with virtual care in seven states. About Dr. Laeeq