Cognitive & neuro

VIP (vasoactive intestinal peptide)

A 28-amino-acid neuropeptide involved in circadian rhythm and brain inflammation, with no approved cognitive use.

Anecdotal evidenceInvestigationalAdd to compare

What it is

Vasoactive intestinal peptide is a 28-amino-acid neuropeptide of the same family as PACAP. In the brain it helps set circadian rhythms in the suprachiasmatic nucleus and modulates immune signalling in microglia. A synthetic form, aviptadil, has been licensed in some countries for erectile dysfunction by injection and studied as an inhaled treatment for lung disease; brain uses remain experimental.

How it works

1
Activates VPAC1 and VPAC2 receptors, raising cAMP in target cells.
2
Shifts circadian clock gene expression in the suprachiasmatic nucleus.
3
Dampens inflammatory signalling in microglia and macrophages.
4
Relaxes vascular and bronchial smooth muscle.
5
Modulates learning-related plasticity in hippocampal slices.

What it's studied for

Circadian rhythm and sleep research

Neuroinflammation in animal models

Pulmonary disease and sarcoidosis with inhaled aviptadil

Erectile dysfunction with injectable aviptadil in some countries

Reported and studied effects

Clear vasodilation and flushing in humans
Cognitive or memory effects are not established in people
Preclinical anti-inflammatory effects in the brain
Hypotension limits systemic dosing

Research protocol notes

Research context only

Research context only - brain applications are experimental. Inhaled and injectable forms used in trials delivered microgram to nanogram per kilogram doses, and central nervous system studies have mostly been intranasal or intracerebroventricular in animals. No human cognitive protocol exists.

These figures are described so you can understand what researchers did. They are not a dose, a schedule, or a suggestion — and they are not a substitute for a doctor.

Possible side effects and contraindications

Safety profile

Possible side effects

Flushing
Hypotension
Tachycardia
Headache
Dizziness

Contraindications and cautions

Low blood pressure or unstable cardiac disease
Not for use in pregnancy outside specialist care
No approved use for any cognitive condition

A side-effect list is never complete, and these are not the only situations that warrant caution. Anything unexpected, or anything you are unsure about, should be discussed with a doctor before use.

Evidence assessment

Anecdotal evidenceNo controlled human data

No controlled human data

Human data exist for vascular and lung effects, but nothing in humans supports cognitive claims; those rest on animal and cell work.

References

References link to published literature, regulator pages or literature indexes. Where a link points to a search, it collects the peer-reviewed work on that molecule rather than a single study.

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