What it is
Vasoactive intestinal peptide is a hormone of 28 amino acids that your body makes. It was isolated from intestinal tissue in 1970, which gave it its name, and then turned up nearly everywhere else — in the lungs, the brain, the pancreas, and throughout the peripheral nervous system.
What it does is broad rather than specific:
- relaxes smooth muscle
- dilates blood vessels
- increases secretion in the intestine
- modulates immune and inflammatory signalling
It belongs to the same peptide family as secretin and glucagon, and it shares receptors with a close relative called PACAP.
The gap this entry exists to explain
VIP is one of the most heavily studied peptides in human biology. On 2026-09-09, PubMed indexed 15,146 records for it, of which 91 are tagged as randomized controlled trials. By the standards of this library that is an enormous evidence base — the growth hormone secretagogue hexarelin has 313 records and 27 trials, and most compounds here have far less.
And yet there is no approved VIP medicine. A DailyMed search on the same date returned exactly one record, and it is worth quoting what it actually is:
AX PHARMACEUTICAL CORP (VASOACTIVE INTESTINAL PEPTIDE) POWDER — published 2017-08-24
That is a bulk powder registration by a chemical supplier. Not a medicine, not a label, not an approved indication. Suppliers of raw pharmaceutical substances register in the same database that carries drug labels, which means a search hit there is not evidence of approval — a distinction that is easy to lose and easy to exploit.
So the accurate summary is: fifteen thousand papers, ninety-one randomized trials, and zero approved products.
Why the gap exists
The literature and the registry are counting different things. The registry counts studies that give something to participants; only 19 interventional registrations name VIP. The 15,146 papers are overwhelmingly about VIP as a signal the body produces — where it is made, what it binds, what it regulates, what happens in disease.
Turning a natural signalling peptide into a drug is a separate problem, and a hard one. VIP breaks down quickly in the body, and it acts at many sites at once — precisely the opposite of the narrow, durable action a medicine needs.
This library has now documented four distinct reasons a trial registry can look empty, and they are not interchangeable:
| Reason | Example |
|---|---|
| Jurisdictional — the work happened outside registry-covered systems | the Russian nootropic prescribed for stroke |
| Chronological — the work predates mandatory registration | Hexarelin |
| Genuinely untested — the thing sold has never been studied | Follistatin |
| Wrong instrument — the research is real but not interventional | VIP |
Writing "no registered trials" without saying which one applies misleads the reader, in one direction or the other.
The correction worth carrying
A VIPoma is a rare neuroendocrine tumour that secretes vasoactive intestinal peptide in excess. It produces severe watery diarrhoea, potassium loss and dehydration — a recognised clinical syndrome caused by nothing other than too much of this peptide.
That matters here because the sales framing for VIP, as for many endogenous peptides, rests on an unstated assumption: the body makes it, so more of it must help. There is a defined disease that consists of exactly having more of it.
The measurement-not-administration pattern this entry describes repeats almost exactly on the body's only cathelicidin: a large human literature built by measuring how much of the peptide a person has, and a registry in which half the entries are observational.
What is actually sold
VIP is most often supplied as a compounded nasal spray, prescribed off-label, and marketed for chronic inflammatory conditions, immune regulation and illness attributed to mould exposure. It is also sold as a lyophilised research powder.
None of those uses is what the 91 randomized trials in the literature were testing, and none has been reviewed by a regulator. The size of the VIP literature is real; it does not transfer to the specific claims made for the product.