Peptide & Experimental
VIP (Vasoactive Intestinal Peptide)
Neuropeptide (28 amino acids), immune- and vessel-modulating · Vasoactive Intestinal Peptide, aviptadil
VIP is an endogenous messenger that widens blood vessels and slows excessive immune reactions. In the scene it is best known as a nasal spray against chronic inflammation after mold exposure. The biology is solid, the clinical studies show a mixed picture, and for nasal spray use there is exactly one small open-label study.
In short
VIP, the vasoactive intestinal peptide, is an endogenous peptide of 28 amino acids released by nerve and immune cells. It dilates blood vessels, stimulates secretion in the gut and dampens inflammatory responses. In humans the vascular effect is clearly established; in combination with phentolamine it is even approved in Germany as an injection into the erectile tissue. The hope for an anti-inflammatory therapy was not fulfilled in the largest study, in severe COVID-19; a smaller inhalation study was positive. For the use as a nasal spray against CIRS that is widespread in the scene, there is only one open-label study with 20 patients without a control group.
What VIP is
VIP was isolated from pig small intestine by Said and Mutt in 1970. Even the first description noted the breadth of its effects: vasodilation, a drop in blood pressure, increased cardiac output, stimulation of breathing. The peptide consists of 28 amino acids. Today the name is misleading, because VIP occurs not only in the gut but throughout the nervous system, in the lungs and in immune cells.
VIP exerts its effects via three receptors, VPAC1, VPAC2 and PAC1. It shares the first two with a related messenger called PACAP. In the brain, VIP is involved in the internal clock, learning and stress responses; in the periphery, in blood flow, intestinal secretion and immune regulation. As a drug, the synthetic form is called aviptadil.
How it is supposed to work
Two effects are central. The first is vasodilation: VIP relaxes the smooth muscle of the vessel walls, in the lungs as well as in the erectile tissue. The second is immune regulation. VIP is produced by immune cells themselves, slows the release of pro-inflammatory messengers such as TNF-alpha and favors the formation of regulatory T cells, which dampen excessive immune responses.
The idea of using VIP against chronic inflammation stems from this second effect. It is well supported in the laboratory and has been tested in humans mainly in the lungs, in sarcoidosis, pulmonary hypertension and acute lung failure. A practical hurdle is the short half-life: VIP is broken down very quickly in the body, which is why it is inhaled, injected or given as a nasal spray.
What it is used for
Aviptadil is approved only in one niche: together with phentolamine as an injection into the erectile tissue for erectile dysfunction, according to a list of the European Medicines Agency in Germany, Denmark, Finland and France, among others. In clinical research it was tested as an infusion and by inhalation in severe COVID-19.
In the biohacking scene, VIP is best known as a nasal spray, specifically from the context of the CIRS concept. CIRS stands for a chronic inflammatory syndrome said to develop after time spent in damp-damaged, mold-contaminated buildings. In the multi-step treatment protocol of the physician Ritchie Shoemaker, VIP is used in patients whose symptoms persist despite other measures. It is also used for immune balance, lung health and recovery after infections.
What users report
Most reports come from the CIRS context. The only published paper on this describes 20 patients who used VIP as a nasal spray for at least 18 months. According to the authors, symptoms improved in all of them, inflammatory markers normalized, and no one stopped because of side effects. This is a report without a control group from the group that developed the protocol itself. It should be taken seriously, but it does not prove an effect, because chronic symptoms can also change without treatment and through the other steps of the protocol.
What is well supported
It is well supported that VIP dilates blood vessels and influences immune cells in humans. Inhaled, it selectively dilated the pulmonary vessels in 20 patients with pulmonary hypertension without lowering blood pressure in the systemic circulation. In 20 patients with active sarcoidosis, four weeks of inhalation reduced the production of TNF-alpha in cells from the lungs and increased the number of regulatory T cells, the first demonstration of this immune effect in humans.
The approval of the erectile tissue injection also shows that the vascular effect holds up clinically. In an analysis of 308 men in whom the standard injection did not work or was painful, the combination of aviptadil and phentolamine worked in 59 percent.
What the studies show
Inhalation in COVID-19 pneumonia, 80 patients, 2025
In a double-blind study at 9 hospitals, 80 inpatients received inhaled aviptadil or placebo in addition to standard therapy. The aviptadil group was discharged after an average of 7.8 days, the placebo group after 10 days, narrowly significant. On CT, lung damage improved more by day 28. Deaths were 5.1 versus 12.2 percent, but this was not a tested endpoint.
Infusion in lung failure, TESICO, 2023
The largest study to date ran at 28 US centers, funded by the National Institutes of Health. 461 patients with COVID-19 and acute lung failure received intravenous aviptadil or placebo. After 90 days, both groups fared the same; 38 versus 36 percent had died. The study was stopped in 2022 for futility. A 2025 meta-analysis with 665 patients likewise found no survival benefit.
Sarcoidosis, 20 patients, 2010
Prasse and colleagues had 20 patients with confirmed, active sarcoidosis inhale VIP for 4 weeks. The treatment was safe and well tolerated. Cells from lung lavage produced less TNF-alpha, and regulatory T cells increased. The study was open-label, without a placebo group, and measured immune markers, not clinical endpoints such as lung function.
Where the data stop
For the use that is usually at issue in the scene, the data are insufficient. For CIRS treatment by nasal spray there is only the open-label study with 20 patients, without placebo, published outside the major databases. The literature on CIRS as a whole also comes predominantly from the circle of the protocol’s originators: a 2024 review that calls the Shoemaker protocol the only effective treatment relies for this on 11 of 13 articles on exactly this protocol.
Beyond CIRS, too, the picture is mixed. The large infusion study was negative, the positive inhalation study small and narrow. The data on sarcoidosis and pulmonary hypertension are uncontrolled and short; in pulmonary hypertension, according to the authors, the effect was modest and short-lived. For general goals such as immune balance or longevity in healthy people there are no studies.
Status, approval and legal
Aviptadil is approved in Germany in exactly one form: together with phentolamine as an injection into the erectile tissue for erectile dysfunction, prescription-only. There is no approved VIP nasal spray; it is obtained via pharmacy-compounded prescriptions or the gray market. Usage and dosage information is therefore omitted. The 2026 Prohibited List of the World Anti-Doping Agency does not name VIP explicitly.
Safety
VIP dilates blood vessels, so the typical side effect is facial flushing. In the analysis of the erectile tissue injection, it occurred in 22.5 percent of the men. Inhaled, VIP was well tolerated in the small studies; in severely ill patients receiving infusions, serious events occurred about as often as under placebo. What a permanent excess of VIP does is shown by rare VIP-producing tumors: watery diarrhea, potassium deficiency and flushing. That is an extreme example, not a statement about nasal spray. Anyone with low blood pressure or taking blood-pressure-lowering medication should bear the vasodilating effect in mind. For compounded and gray-market products, any quality control is lacking. Pregnancy and breastfeeding have not been studied.
BK-Score Thin human evidence
| Human evidence | 4 | |
|---|---|---|
| Mechanism | 6 | |
| Safety data | 4 | |
| Hype gap | 2 | |
| Track record of use | 3 |
Evidence 4: the vascular effect is established in humans, and the combination of aviptadil and phentolamine is nationally approved as an injection into the erectile tissue in Germany, among other countries (list of the European Medicines Agency 2022). For the advertised anti-inflammatory effect the picture is mixed: the largest randomized trial (TESICO, Lancet Respir Med 2023, 461 patients, intravenous in COVID-19) missed its endpoint and was stopped, a 2025 meta-analysis found no survival benefit, and a smaller double-blind inhalation study with 80 patients shortened the hospital stay with narrow significance. For the nasal spray against CIRS there is only one open-label study with 20 patients without a control group (Shoemaker 2013). Mechanism 6, because vasodilation and the immune effect (less TNF-alpha, more regulatory T cells in sarcoidosis) have been measured in humans. Safety 4: short controlled studies, flushing as the most common side effect. Direction mixed rather than open, because controlled data point in both directions.
The score rates the state of knowledge, not the substance. “Safety data 9” means well studied – not harmless.
Subjective assessment by Biohacking Kompakt based on published scoring rules – not a scientific rating and not a medical recommendation. Rules and all ratings (German)
Frequently asked questions about VIP (vasoactive intestinal peptide)
What is VIP?
VIP stands for vasoactive intestinal peptide, an endogenous messenger of 28 amino acids. It dilates blood vessels, stimulates intestinal secretion and dampens inflammatory responses. The synthetic form is called aviptadil.
Does VIP nasal spray help with CIRS after mold exposure?
There is only one open-label study on this with 20 patients without a control group, in which, according to the authors, all of them improved. That is an indication, not proof. Controlled and independent studies are lacking.
Is VIP approved in Germany?
Only in one form: aviptadil together with phentolamine as an injection into the erectile tissue for erectile dysfunction. There is no approved VIP nasal spray.
Did VIP help in COVID-19?
The largest study with infusions in severe lung failure was negative and was stopped. A smaller study with inhaled aviptadil showed a somewhat faster discharge from hospital. A meta-analysis found no survival benefit.
What side effects does VIP have?
The most common is facial flushing due to vasodilation. A drop in blood pressure and diarrhea are also possible. In the small inhalation studies, VIP was well tolerated.
Is VIP banned in sport?
The 2026 Prohibited List of the World Anti-Doping Agency does not name VIP explicitly. Anyone who competes in sport should nevertheless clarify this with the responsible anti-doping body.
Related
- Same substance classDSIP
- Same substance classOxytocin
- Related topicThymosin Alpha-1 (TA1)
- Same sectionThymalin
- Same sectionThymosin Beta-4 (full-length)
- Same sectionTB-500 (Thymosin Beta-4 Fragment)
- Same sectionPT-141
- Same sectionKPV
Sources
- Said SI, Mutt V, Science 1970 — discovery, 28 amino acids
- Delgado M, Ganea D, Amino Acids 2013 — VIP and immune functions
- Prasse A et al., American Journal of Respiratory and Critical Care Medicine 2010 — inhaled VIP in sarcoidosis
- Leuchte HH et al., European Respiratory Journal 2008 — inhaled VIP in pulmonary hypertension
- Brown SM et al., Lancet Respiratory Medicine 2023 — TESICO, intravenous aviptadil in COVID-19
- Esendagli D et al., Medical Principles and Practice 2025 — inhaled aviptadil, 80 patients
- Udupa AA et al., Indian Journal of Critical Care Medicine 2025 — meta-analysis of aviptadil in ARDS
- Shoemaker RC et al., Health 2013 — VIP nasal spray in CIRS, open-label study
- Al-Mitwalli A et al., Journal of Sexual Medicine 2025 — aviptadil and phentolamine, 308 men
- European Medicines Agency 2022 — nationally authorized products containing aviptadil and phentolamine
Open in the database – with search, filters and comparison (German app)
Information only, not medical advice and not a usage or dosage recommendation. Prescription-only and unapproved substances belong in the hands of a physician. Last updated: 2026-09-30.