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

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ToolsCompareP21 vs VIP

P21 vs VIP

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

Cognitive EnhancementAnti-Aging & Longevity
P21
Immune SupportSleep Optimization
VIP
Summary
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.
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.
Half-Life
Not well characterized; likely short, but neurogenic effects persist long after administration
~2 minutes in plasma (rapidly degraded by peptidases); intranasal delivery may extend local CNS effects
Admin Route
SubQ, Intranasal
Intranasal, SubQ, IV
Research
Typical Dose
100–500 mcg
50 mcg (4 sprays of 12.5 mcg each)
Frequency
Once daily
4x daily
Key Benefits
  • 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
  • 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
Side Effects
  • Generally well tolerated in animal studies
  • Limited human clinical data
  • Injection site reactions
  • Potential mild fatigue at initiation
  • Facial flushing (transient, intranasal)
  • Mild nausea
  • Headache at initiation
  • Hypotension at high doses
  • +1 more
Stacks With