Carl read the papersWhat it actually is
VIP was pulled out of pig small intestine in 1970 and described as a polypeptide of 28 amino acids causing vasodilation, a drop in blood pressure, higher cardiac output, respiratory stimulation and higher blood sugar. It is a genuine signalling peptide of the body's own, found in nerves through the gut, lung and blood vessels.
Aviptadil is synthetic VIP. The same molecule has been developed three separate ways: injected into the penis with phentolamine for erectile dysfunction, inhaled or intravenous for lung disease, and, outside any approval, as a nasal spray in the chronic inflammatory response syndrome (CIRS) protocol, which is where almost all online interest comes from.
How it’s thought to work
- VPAC receptors — Signals through the VPAC1 and VPAC2 receptors, which are spread through lung, gut, immune and vascular tissue. That breadth is why it has been tried in so many unrelated conditions.
- Vasodilation — The original observed effect, and the basis of the erectile dysfunction product. The French insert describes VIP relaxing the smooth muscle that controls venous outflow, while phentolamine blocks alpha-adrenergic tone.
- Immune modulation — In a 4 week open study in sarcoidosis, nebulised VIP reduced TNF-alpha production by cells from lung washings and raised regulatory T cells.
- Lung protection — The rationale behind the COVID programme, based on animal and cell work on surfactant and cytokines. The clinical trials did not bear it out.
What the research says
Three different stories. Erectile dysfunction: the aviptadil plus phentolamine combination is licensed, and a retrospective single-centre series of 308 men who had failed other treatments found it effective in 182 of them (59%), with facial flushing in 69 (22.5%) and ischaemic priapism in one patient (0.3%). Lung disease: a single inhaled 100 mcg dose produced only a small and short-lived pulmonary vasodilation in 20 patients, and the large randomised TESICO trial of intravenous aviptadil in COVID respiratory failure was stopped for futility, with 90 day mortality of 38% on aviptadil against 36% on placebo in 461 patients. An earlier 196 patient trial missed its primary endpoint as well, although it reported a survival difference in a secondary analysis. CIRS: one open-label study, 20 patients, nasal VIP at 50 mcg four times a day for at least 18 months, no control group, published by the author of the protocol it tests.
- Licensed as aviptadil 25 mcg with phentolamine mesilate 2 mg for injection into the penis for erectile dysfunction in France, and accepted for restricted NHS use in Scotland.
- Effective in 59% of 308 men with refractory erectile dysfunction in a single-centre series; facial flushing was the common side effect.
- TESICO (461 patients) found no benefit in COVID respiratory failure and the aviptadil arm was stopped for futility.
- A 4 week nebulised VIP study in sarcoidosis showed measurable immune changes in 20 patients, with no clinical endpoints.
- The CIRS nasal spray protocol rests on one open-label study of 20 patients with no placebo group.
Reported protocols
These are the doses the peptide community actually reports running (Reddit & forums), alongside published research — logged for education, not as a recommendation to use.
| Parameter | Commonly reported range |
|---|---|
| Label dose (erectile dysfunction) | Aviptadil 25 mcg with phentolamine mesilate 2 mg in one 0.35 mL ampoule, injected into the penis, no more than once a day and no more than three times a week. Prescription only, and the French insert says the first injections must be given by qualified medical staff |
| Published nasal protocol (CIRS) | 50 mcg four times daily by nasal spray in the one open-label study, continued for at least 18 months and then titrated down. That study excluded people with MARCoNS in the nose, a high mould index in house dust or depressed visual contrast sensitivity, which is part of the protocol, not a footnote |
| Trial doses (lung) | A single inhaled 100 mcg dose in pulmonary hypertension; TESICO infused it intravenously in hospital over 12 hours a day for 3 days, targeting 600, then 1200, then 1800 pmol/kg |
| Community dose | Not established from independent sources. The ranges circulating online come from vendor and clinic pages rather than from reports people have written up themselves |
| Route | Intranasal, into the penis, inhaled or intravenous, depending on which of the three VIPs you mean |
| Carl's note | The nasal and the injectable versions are not interchangeable in any sense. One is a licensed product with a maximum frequency on its insert, the other is a protocol dose from a single clinic. |
Common use cases
| Goal | Community protocol notes |
|---|---|
| Erectile dysfunction, second line | the licensed use, after oral medicines have failed, and taught in a clinic |
| CIRS and mould illness protocols | the reason most people find VIP, resting on a single uncontrolled study |
| Inflammatory lung research | sarcoidosis and pulmonary hypertension work, both small and exploratory |
Mixing it (reconstitution)
Freeze-dried peptides must be reconstituted with bacteriostatic water before they can be measured. Carl’s calculator turns “mg in the vial + ml of water + target dose” into “units on the syringe” — and tells you how long the vial lasts.
→ Open the Reconstitution Calculator
Injection & handling
This is the rare entry where the injectable form is the one you should not be starting on your own. The licensed aviptadil product goes into the penis, the French insert caps it at once a day and three times a week, says the first injections must be given by qualified medical staff with monitoring in the early phase, and rules it out entirely for anyone on anticoagulants or with conditions that predispose to priapism. Self-injection is taught in a clinic, and in the published series it was taught by a nurse-led clinic with telephone follow-up. The nasal form that most people mean when they say VIP is a spray, not a needle: refrigerated, measured in micrograms per spray, and compounded. If what is in front of you is a research vial of powder with a concentration you cannot verify, there is no sound way to turn that into a nasal dose at home.
Stacks it appears in
- With phentolamine — The licensed pairing, and the only VIP combination with a regulator's approval behind it.
- Inside the CIRS protocol — In that protocol VIP is the last step, after exposure is removed and the earlier treatments are done, not a standalone. Taking the last step first is the common mistake.
- With other immune peptides — Thymosin Alpha-1 and LL-37 come up in the same conversations, through entirely different mechanisms and with no combination data.
Sources
- Said SI, Mutt V. Polypeptide with broad biological activity: isolation from small intestine. Science 1970 (PMID 5450698)
- ANSM SmPC for INVICORP 25 micrograms / 2 mg solution for injection (aviptadil with phentolamine mesilate), updated 05/10/2018
- Scottish Medicines Consortium advice on aviptadil/phentolamine mesilate (Invicorp), SMC ID 1284/17
- Al-Mitwalli A et al. Intracavernosal injection of aviptadil and phentolamine for refractory erectile dysfunction. J Sex Med 2025 (PMID 40192471)
- Brown SM et al. Intravenous aviptadil and remdesivir for COVID-19 (TESICO). Lancet Respir Med 2023 (PMID 37348524)
- Youssef JG et al. The use of IV vasoactive intestinal peptide (aviptadil) in patients with critical COVID-19 respiratory failure. Crit Care Med 2022 (PMID 36044317)
- Prasse A et al. Inhaled vasoactive intestinal peptide exerts immunoregulatory effects in sarcoidosis. Am J Respir Crit Care Med 2010 (PMID 20442436)
- Leuchte HH et al. Inhalation of vasoactive intestinal peptide in pulmonary hypertension. Eur Respir J 2008 (PMID 18978135)
- Couvineau A, Laburthe M. VPAC receptors: structure, molecular pharmacology and interaction with accessory proteins. Br J Pharmacol 2012 (PMID 21951273)
- Shoemaker RC, House D, Ryan JC. Vasoactive intestinal polypeptide (VIP) corrects chronic inflammatory response syndrome (CIRS). Health 2013;5(3):396-401
- SAHPRA registered health products register (no aviptadil or VIP product)
- SAHPRA, Peptide Products public information page (May 2026)
- WADA 2026 Prohibited List
