VIP (vasoactive intestinal peptide): research, side effects and dosage in studies

In short

VIP, or vasoactive intestinal peptide, is the body's own peptide, whose synthetic form aviptadil did not help severe COVID-19 in a large placebo-controlled trial [3]A. Combined with phentolamine it is a medicine for erectile dysfunction in some European countries [12]regulator.

• In the largest trial, in 461 COVID-19 patients, aviptadil given into a vein did not improve outcomes at 90 days, and the trial was stopped for futility [3]A.
• The best-studied use is injection treatment of erectile dysfunction with VIP and phentolamine: 75% responded, versus 12% with placebo [6]A.
• For VIP treatment of mould-related symptoms (CIRS) there is only one published case report [11]B.
• In Finland aviptadil is on the medicines list, and the combination product has held a national marketing authorisation [12, 15]regulator. The WADA list does not name VIP [16]regulator.

What is VIP?

VIP, or vasoactive intestinal peptide, is a 28-amino-acid peptide found in both the central and peripheral nervous system. It is released by nerve cells and immune cells, and it acts as a neurotransmitter, immune regulator, vasodilator and secretagogue [1].

Aviptadil is the synthetic form of VIP that has been studied as a medicine [2, 5]A. The combination product used for erectile dysfunction (Invicorp) contains VIP and phentolamine [9] [12]regulator.

Basics: What are peptides?. All substances: Peptides A-Z.

Evidence at a glance

Each cell gives the kind of study and its source. The letter is the evidence level, not the result.

"-" = no such study is known.

What is VIP used for?

The only use of VIP that has had a marketing authorisation is injection treatment of erectile dysfunction together with phentolamine. The combination product has held national marketing authorisations in several European countries, including Finland [12]regulator.

• Erectile dysfunction: a combination of VIP and phentolamine injected into the penis, studied in placebo-controlled trials [6, 7]A.
• Severe COVID-19 and respiratory failure: aviptadil given into a vein or inhaled [2, 3, 4]A. In the largest trial there was no benefit [3]A.
• Acute respiratory distress syndrome (ARDS): aviptadil received an EU orphan designation in 2026, but a designation is not a marketing authorisation [13]regulator.

Claims online. Online, nasal VIP spray is described as a treatment for mould-related symptoms (CIRS). There is only one published case report on it [11]B.

How does VIP work?

VIP widens blood vessels, regulates the immune system, increases secretion and acts as a neurotransmitter [1]. Aviptadil has been studied as a medicine for respiratory failure [2, 5]A.

In the erectile dysfunction combination the two substances act differently: VIP helps keep blood in the penis, and phentolamine increases blood flow [9]. So the results of the combination cannot be transferred to VIP alone.

Has VIP been studied in humans?

Yes, VIP has been studied in humans. There are several randomised placebo-controlled trials of VIP and aviptadil in COVID-19 and erectile dysfunction [2, 3, 4, 6, 7]A.

COVID-19 and respiratory failure

• TESICO (2023). 461 hospital patients with COVID-19 respiratory failure, 94% of them in intensive care, received aviptadil or placebo. The overall outcome at 90 days did not differ between groups, and mortality was 38% with aviptadil and 36% with placebo. The trial was stopped for futility [3]A.
• Youssef (2022). In a trial of 196 patients, the primary goal, survival free of respiratory failure at 60 days, was not met. The investigators reported better survival as a secondary result [2]A.
• Meta-analysis (2025). The pooled result of two randomised trials showed no survival benefit. The authors say larger and well-designed trials are needed [5]A.
• Inhaled (2025). In a trial of 80 hospital patients, the aviptadil group went home after 7.8 days on average and the placebo group after 10 days (p = 0.049). The trial was small [4]A.

Erectile dysfunction

• Dinsmore (1999). In a placebo-controlled phase with 171 men, 75% responded to the VIP and phentolamine combination, versus 12% to placebo [6]A.
• Sandhu (1999). In a trial of 195 men the figures were 75.1% and 12% [7]A.
• Al-Mitwalli (2025). In a retrospective series of 308 men in whom alprostadil injections had caused intolerable pain or failed, the combination worked for 59% [10]B.

Mould exposure (CIRS)

We know of only one published case report. In it, the patient's symptoms eased when the exposure ended and several treatments were used at the same time, one of them VIP, so the role of VIP cannot be separated [11]B. There are no controlled studies.

Who studies VIP?

The largest COVID-19 trial of VIP, TESICO, was done in the United States [3]A. The placebo-controlled erectile dysfunction trials date from the 1990s [6, 7]A, and the newest series comes from patients at a specialist clinic [10]B. Trials in respiratory failure have been pooled in a meta-analysis [5]A.

Who wrote this page: the editorial team

This page was written by the Molecular Recovery editorial team. The draft was made with the help of AI, and the claims were checked against the sources (AI policy). The page has not been medically reviewed. How we work: About us.

What are the side effects of VIP?

With injection treatment the most common side effect was temporary facial flushing. In severe COVID-19, harms did not differ significantly from placebo [3, 6]A.

Injection treatment for erectile dysfunction

Flushing accompanied 40% of 1,711 injections. Prolonged erection (priapism) occurred once [6]A. In a newer series, flushing occurred in 22.5% and priapism in 0.3% of men [10]B. Compared with alprostadil, the combination caused pain much less often [8]A.

Aviptadil given into a vein

In the TESICO trial, death, a serious adverse event, organ failure, serious infection or a severe adverse event within five days occurred in 63% of the aviptadil group and 56% of the placebo group. The difference was not statistically significant (p = 0.10) [3]A. More: Side effects and safety.

Interactions and who has no data

According to the product information of the erectile dysfunction combination product, it should not be used together with other erectile dysfunction medicines, and no interactions have been seen with blood pressure medicines or other cardiovascular medicines [18]official. There are no research data on other interactions. The erectile dysfunction trials were done in men [6, 7]A and the COVID trials in hospital patients [2, 3]A, so there are no data, for example, on pregnancy. Treatment and its interactions are decided by a doctor.

Evidence against and what is unknown

The largest and best COVID-19 trial found no benefit [3]A, and the erectile dysfunction results concern the combination, not VIP alone [9].

Evidence against

• The TESICO trial was stopped for futility [3]A.
• In the Youssef trial the primary goal was not met [2]A, and the meta-analysis showed no survival benefit [5]A.
• In a comparison, alprostadil worked slightly more often than the VIP and phentolamine combination (83% vs 73%) [8]A.

What the evidence does not support

• "Aviptadil cures severe COVID-19": not shown. In the large TESICO trial aviptadil did not improve outcomes at 90 days [3]A.
• "VIP is a new and untested substance": that is not true. The combination was studied in placebo-controlled trials as early as the 1990s [6, 7]A, and it has held national marketing authorisations in several European countries [12]regulator.
• "Nasal VIP is a proven treatment for mould-related symptoms": it is not. There is only one case report, where VIP was one of many simultaneous treatments [11]B.
• "The FDA has granted aviptadil emergency use authorisation": aviptadil was not on the FDA list of emergency use authorisations on 12 Oct 2026 [14]regulator.

What is not known

• Whether some group of patients with respiratory failure benefits. According to a meta-analysis, larger trials are needed [5]A.
• Whether inhaled aviptadil helps. The only trial was small [4]A.
• Whether VIP helps mould-related symptoms. There is only a single case report [11]B.

VIP dosage in studies

Approved dosing exists only for the combination product of aviptadil and phentolamine (Invicorp), which has held a national marketing authorisation in Finland [12]regulator. According to the Norwegian summary of product characteristics the dose is one ampoule (25 µg aviptadil and 2 mg phentolamine) injected into the penis, at most once a day and three times a week, and the first injections are given by a healthcare professional [18]official. The dose is set by a doctor. Below are the doses used in studies. They were given in hospital or under medical supervision, and they are not recommendations.

What the numbers do not tell you. The figures concern pharmaceutical products under supervised conditions. They say nothing about doses of VIP products ordered online, such as nasal sprays. A fuller table with sources: VIP doses used in studies. Unit converter: VIP calculator.

VIP combination vs alprostadil: what is the difference?

The VIP combination and alprostadil are both injection treatments for erectile dysfunction. In a comparison trial alprostadil worked slightly more often (83% vs 73%), but the VIP and phentolamine combination caused pain much less often [8]A.

In men in whom alprostadil had caused intolerable pain or failed, the combination worked for 59% in a retrospective series [10]B. The treatment is chosen by a doctor.

Status in the United States

Aviptadil was not on the FDA list of emergency use authorisations for drugs and biological products on 12 Oct 2026 [14]regulator.

Is VIP legal in Finland?

In Finland VIP is a medicinal substance: aviptadil is on the medicines list, and the combination product has held a national marketing authorisation [12, 15]regulator.

• Medicines list. Aviptadil is in annex 1 of the Finnish medicines list (Fimea decision 230/2025), and annex 1 substances are controlled as medicines [15]regulator.
• Marketing authorisation. In EMA's 2022 list, the combination product of aviptadil and phentolamine (Invicorp) held national marketing authorisations in Finland, Sweden, Norway, Denmark, Germany and France, among others [12]regulator. In the Article 57 database, Invicorp was still recorded for Finland (data as of 21 Sep 2026) [17]regulator. An authorisation alone does not show whether the product is currently in pharmacies; a pharmacy can confirm that.
• EU. EMA's data on centrally authorised medicines contain no VIP or aviptadil. Orphan designations have been given to aviptadil for acute lung injury (2006), sarcoidosis (2007) and ARDS (2026), and to VIP for pulmonary hypertension (2003) [13]regulator.
• Import. Ordering medicines from outside the EU is covered on Peptides and the law. Bringing them back from travel: Travelling with peptides.

This is not legal advice. Disclaimer.

How to assess a VIP product

Studies used pharmaceutical products in hospitals or specialist clinics [3, 10]. They say nothing about the content or purity of other VIP products, for example those ordered online.

A seller's own certificate of analysis (COA) does not show quality by itself. More: How to read a COA and check a test result. Handling: Mixing and handling.

FAQ

Read the research yourself: sources

Every source opens the original publication or the regulator's page. The level shows what the source itself reports.

1. Delgado M, Ganea D. Vasoactive intestinal peptide: a neuropeptide with pleiotropic immune functions. Amino Acids. 2013;45(1):25-39. PMID 22139413 (review)
2. Youssef JG, Lavin P, Schoenfeld DA, et al. The Use of IV Vasoactive Intestinal Peptide (Aviptadil) in Patients With Critical COVID-19 Respiratory Failure: Results of a 60-Day Randomized Controlled Trial. Crit Care Med. 2022;50(11):1545-1554. PMID 36044317 A
3. Brown SM, Barkauskas CE, Grund B, et al. Intravenous aviptadil and remdesivir for treatment of COVID-19-associated hypoxaemic respiratory failure in the USA (TESICO): a randomised, placebo-controlled trial. Lancet Respir Med. 2023;11(9):791-803. PMID 37348524 A
4. Esendagli D, Sarı N, Akhan S, et al. Inhaled Aviptadil Is a New Hope for Recovery of Lung Damage due to COVID-19. Med Princ Pract. 2025;34(2):191-200. PMID 39870064 A
5. Udupa AA, Todur P, Chaudhuri S, et al. Aviptadil Therapy in Acute Respiratory Distress Syndrome Patients: A Systematic Review and Meta-analysis. Indian J Crit Care Med. 2025;29(11):942-953. PMID 41368449 A
6. Dinsmore WW, Gingell C, Hackett G, et al. Treating men with predominantly nonpsychogenic erectile dysfunction with intracavernosal vasoactive intestinal polypeptide and phentolamine mesylate in a novel auto-injector system: a multicentre double-blind placebo-controlled study. BJU Int. 1999;83(3):274-279. PMID 10233493 A
7. Sandhu D, Curless E, Dean J, et al. A double blind, placebo controlled study of intracavernosal vasoactive intestinal polypeptide and phenotolamine mesylate in a novel auto-injector for the treatment of non-psychogenic erectile dysfunction. Int J Impot Res. 1999;11(2):91-97. PMID 10356669 A
8. Shah PJ, Dinsmore W, Oakes RA, Hackett G. Injection therapy for the treatment of erectile dysfunction: a comparison between alprostadil and a combination of vasoactive intestinal polypeptide and phentolamine mesilate. Curr Med Res Opin. 2007;23(10):2577-2583. PMID 17875241 A
9. Dinsmore WW, Wyllie MG. Vasoactive intestinal polypeptide/phentolamine for intracavernosal injection in erectile dysfunction. BJU Int. 2008;102(8):933-937. PMID 18485029 (review)
10. Al-Mitwalli A, Holden F, Di Giovanni A, et al. Intracavernosal injection of aviptadil and phentolamine for refractory erectile dysfunction. J Sex Med. 2025;22(5):726-730. PMID 40192471 B
11. Gunn SR, Gunn GG, Mueller FW. Reversal of Refractory Ulcerative Colitis and Severe Chronic Fatigue Syndrome Symptoms Arising from Immune Disturbance in an HLA-DR/DQ Genetically Susceptible Individual with Multiple Biotoxin Exposures. Am J Case Rep. 2016;17:320-325. Case report (1 patient). PMID 27165859 B
12. European Medicines Agency. List of nationally authorised medicinal products, active substances aviptadil / phentolamine mesilate, procedure PSUSA/00010814/202202 (EMA/855871/2022, 27 Oct 2022). EMA regulator
13. European Medicines Agency. Medicine data: medicines and orphan designations data sets of 12 Oct 2026 (no medicine with VIP or aviptadil; orphan designations EU/3/03/173, EU/3/06/395, EU/3/07/473 and EU/3/26/3200). EMA regulator
14. U.S. Food and Drug Administration. Emergency Use Authorizations for Drugs and Non-Vaccine Biological Products (content current as of 1 Jul 2026). FDA regulator
15. Finland. Lääkeluettelo (Fimea medicines list), 230/2025, sections 1-2 and annex 1. Finlex regulator
16. World Anti-Doping Agency. 2026 Prohibited List. WADA regulator
17. European Medicines Agency. Article 57 product data (EMA/518502/2018 Rev.89, data as of 21 Sep 2026): aviptadil + phentolamine (Invicorp) entries, including Finland. EMA regulator
18. Felleskatalogen (Norway). Invicorp (aviptadil 25 µg, phentolamine mesilate 2 mg), Evolan Pharma: text based on the summary of product characteristics approved by the Norwegian Medicines Agency 9 Jul 2026 (dosing, interactions). felleskatalogen.no official

Sources checked 12-13 Oct 2026.

Evidence levels: A = randomised human trial or meta-analysis · B = observational human study or case series · C = animal study · D = cell or laboratory study · E = not peer-reviewed · regulator = a regulator's assessment or decision, not research evidence. The marker official means official product information (summary of product characteristics or label); it is not research evidence. For a review, the level shows what kind of research the statement rests on. No level: statements that something has not been studied, reviews' interpretations, named hypotheses and the general rules in our certificate-of-analysis guide.

Content is general information about research, not medical advice. If you have symptoms, contact a healthcare professional.