New — Free Peptide Starter Guide (2026): 13 chapters, 34 cited studies

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ToolsCompareVIP vs P21

VIP vs P21

Side-by-side comparison of key properties, dosing, and research.

Immune SupportSleep Optimization
VIP
Cognitive EnhancementAnti-Aging & Longevity
P21
Summary
VIP is a 28-amino acid neuropeptide with profound anti-inflammatory, vasodilatory, and immunomodulatory effects. It plays a critical role in gut motility, circadian rhythm, and immune tolerance. Used therapeutically for CIRS (Chronic Inflammatory Response Syndrome), MCAS, and inflammatory conditions.
P21 is a synthetic peptide derived from CNTF (ciliary neurotrophic factor) that promotes hippocampal neurogenesis, enhances memory and spatial learning, and may reduce amyloid-beta pathology. It is used as a neurogenic and cognitive enhancer with potential anti-Alzheimer's applications.
Half-Life
~2 minutes in plasma (rapidly degraded by peptidases); intranasal delivery may extend local CNS effects
Not well characterized; likely short, but neurogenic effects persist long after administration
Admin Route
Intranasal, SubQ, IV
SubQ, Intranasal
Research
Typical Dose
50 mcg (4 sprays of 12.5 mcg each)
100–500 mcg
Frequency
4x daily
Once daily
Key Benefits
  • Potent anti-inflammatory for CIRS and mold illness
  • Improves pulmonary hypertension symptoms
  • Regulates gut motility and IBS symptoms
  • Modulates circadian rhythm and sleep quality
  • Reduces mast cell activation (MCAS)
  • Improves cognitive function in neuroinflammatory conditions
  • Vasodilatory — reduces vascular resistance
  • Promotes hippocampal neurogenesis
  • Enhances spatial memory and learning
  • Increases BDNF expression
  • Reduces amyloid-beta plaque formation (animal models)
  • Anti-tau pathology potential
  • Cognitive enhancement without stimulant effects
  • Potential therapeutic for Alzheimer's and cognitive aging
Side Effects
  • Facial flushing (transient, intranasal)
  • Mild nausea
  • Headache at initiation
  • Hypotension at high doses
  • +1 more
  • Generally well tolerated in animal studies
  • Limited human clinical data
  • Injection site reactions
  • Potential mild fatigue at initiation
Stacks With