Peptide profile · Healing & Recovery
VIP (Vasoactive Intestinal Peptide)
Endogenous neuropeptide with vasodilatory, anti-inflammatory, and immunomodulatory properties
Written & reviewed by Michael Carroll · Research, Peptide Initiative
Typical dose
50 mcg per inhalation (200 mcg/day); 100 mcg single acute dose
Half-life
Approximately 1-2 minutes in plasma (rapid enzymatic degradation)
Bioavailability
IV: 100%; Inhaled: local pulmonary delivery; short systemic half-life
Molecular weight
3325.83 Da
Evidence level
Moderate human trials
01 · Compound profile
Scientific & efficacy data
Molecular formula
C147H237N43O43S
Primary benefits
Potent pulmonary vasodilator via VPAC1/VPAC2 receptor activation with Phase 2 evidence of hemodynamic improvement in pulmonary hypertension
Suppresses TNF-α and IL-6 through VPAC receptor-mediated signaling with Phase 2b/3 evidence of IL-6 reduction in COVID-19 ARDS
VPAC2-dependent neuroprotective effects documented in Parkinson and Alzheimer disease models with microglial modulation
Uppsala University, Sweden
Amino acid sequence
HSDAVFTDNYTRLRKQMAVKKYLNSILN-NH2 (28 amino acids)02 · Dosing
How much do I take?
50 mcg per inhalation (200 mcg/day); 100 mcg single acute dose · four inhalations daily
Subcutaneous injection: A small injection into the fatty layer just under the skin — the same way insulin is given.
Bioavailability High — most of the dose reaches your bloodstream, just more gradually than an IV.
Best time to take
VIP (Vasoactive Intestinal Peptide) is administered intravenously in a clinical setting. Timing is determined by your healthcare provider based on the treatment protocol and your medical needs.
With food?
IV administration of VIP (Vasoactive Intestinal Peptide) is not dependent on meal timing. Your healthcare team will provide specific instructions regarding food and fluid intake around treatment sessions.
If stacking
VIP (Vasoactive Intestinal Peptide) should be used as directed by your healthcare provider. If combining with other medications or supplements, discuss potential interactions with your provider. Avoid combining with compounds that have overlapping mechanisms unless specifically guided by a medical professional.
＋ Increase if
- +You've tolerated the current dose for the recommended period without significant side effects
- +Therapeutic goals haven't been met at the current dose level
- +Your healthcare provider recommends dose escalation based on your response
- +Lab work or clinical assessments support a higher dose
－ Decrease if
- −Side effects are bothersome or impacting daily life despite management strategies
- −You experience any signs of an adverse reaction
- −Lab results indicate the need for dose reduction
- −Your healthcare provider recommends a lower dose based on your response
✓ Signs of right dose
- ✓Therapeutic goals being met with minimal side effects
- ✓Stable and consistent response to treatment
- ✓Lab values or clinical markers trending in the right direction
- ✓Good tolerance with manageable or absent side effects
Dosing Calculator
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03 · Suitability
Is this right for me?
Best for pulmonary arterial hypertension research & ards and respiratory failure investigation
Best for
Pulmonary arterial hypertension research
VIP (Vasoactive Intestinal Peptide) is particularly well-suited for individuals focused on pulmonary arterial hypertension research. Research and clinical experience suggest meaningful benefits in this area when used as part of a comprehensive treatment approach.
ARDS and respiratory failure investigation
VIP (Vasoactive Intestinal Peptide) is particularly well-suited for individuals focused on ards and respiratory failure investigation. Research and clinical experience suggest meaningful benefits in this area when used as part of a comprehensive treatment approach.
Anti-inflammatory therapy development
VIP (Vasoactive Intestinal Peptide) is particularly well-suited for individuals focused on anti-inflammatory therapy development. Research and clinical experience suggest meaningful benefits in this area when used as part of a comprehensive treatment approach.
Neuroprotection studies
VIP (Vasoactive Intestinal Peptide) is particularly well-suited for individuals focused on neuroprotection studies. Research and clinical experience suggest meaningful benefits in this area when used as part of a comprehensive treatment approach.
Consider alternatives if
Do not use if
Use with caution if
Not sure?
Compare VIP (Vasoactive Intestinal Peptide) with similar peptides to find the best fit for your goals.
04 · Administration
How do I use it?
Intravenous infusion · Inhaled
Reconstitution — what you need
Example
Add the recommended volume of bacteriostatic water to the VIP (Vasoactive Intestinal Peptide) vial. Gently swirl (do not shake) until the powder is fully dissolved. The resulting solution should be clear. Calculate your individual dose based on the concentration and your prescribed amount.
Your dose of VIP (Vasoactive Intestinal Peptide) is determined by your healthcare provider. Using an insulin syringe marked in units, draw up the exact amount prescribed. For example, if the reconstituted concentration is 1mg/mL and your dose is 0.5mg, draw up 0.5mL (50 units on an insulin syringe). Always double-check calculations before injection.
Route
Subcutaneous injection (into the fatty tissue just under the skin)—allows for consistent absorption and can be self-administered at home after proper training
Best sites
Technique
- 01Wash your hands thoroughly with soap and water before handling supplies
- 02Clean the injection site with an alcohol swab and let it air dry completely
- 03Pinch a fold of skin at the chosen injection site
- 04Insert the needle at a 45-90 degree angle (depending on needle length and body composition)
- 05Inject the medication slowly and steadily over 5-10 seconds
- 06Release the skin fold and remove the needle, applying gentle pressure with a clean swab
- 07Rotate injection sites to prevent tissue irritation or lipodystrophy
- 08Dispose of the needle safely in a sharps container—never recap or reuse needles
Storage · before reconstitution
Store VIP (Vasoactive Intestinal Peptide) in the refrigerator at 36-46°F (2-8°C) in its original packaging. Protect from light and moisture. Do not freeze. Check the expiration date before use. Some formulations may be stored at room temperature for limited periods—check your specific product labeling.
Storage · after reconstitution
Once reconstituted, VIP (Vasoactive Intestinal Peptide) should be kept refrigerated at 36-46°F (2-8°C) and used within the timeframe specified on your product labeling (typically 14-28 days). Label the vial with the reconstitution date. Do not use if the solution appears cloudy, discolored, or contains particles.
Signs of degradation
Sample daily schedule
05 · Safety
Is it safe?
3 common side effects · 2 serious
VIP (Vasoactive Intestinal Peptide) is a 28-amino acid endogenous neuropeptide with moderate evidence from Phase 1-2 human clinical trials. The synthetic pharmaceutical form (aviptadil/RLF-100) received FDA fast-track designation for COVID-19-associated ARDS, indicating recognition of its therapeutic potential. Critical safety considerations: VIP is a potent vasodilator that causes dose-dependent hypotension and compensatory tachycardia—hemodynamic monitoring is essential during IV administration. Common side effects include facial flushing and diarrhea from its GI effects. Phase 2b/3 COVID-19 ARDS trials (196 patients) reported NO serious drug-related adverse events, a favorable safety signal. However, individual responses to vasodilation vary significantly based on baseline cardiovascular status, medications, and underlying conditions. The peptide's short plasma half-life (1-2 minutes) limits systemic accumulation. Inhaled VIP shows excellent local tolerability for pulmonary applications with minimal systemic absorption.
VIP's therapeutic evidence comes from Phase 1-2 human clinical trials in pulmonary conditions and a Phase 2b/3 COVID-19 ARDS trial (NCT04703816) that showed improved 60-day survival rates. As an endogenous 28-amino-acid neuropeptide, its pharmacology is well-characterized from decades of basic science research. Clinical applications require IV infusion with continuous hemodynamic monitoring.
Common side effects · experienced by some users
Less common
These typically resolve with continued use or dose adjustment.
Stop and seek help if
- ×Severe or worsening side effects that don't improve with dose adjustment or supportive care
- ×Signs of an allergic reaction—rash, hives, swelling, or difficulty breathing
- ×Your healthcare provider recommends discontinuation based on your clinical response
- ×Development of any new medical condition that may be contraindicated with VIP (Vasoactive Intestinal Peptide)
- ×Pregnancy or planning to become pregnant (unless specifically approved for use during pregnancy)
- ×Abnormal lab results or clinical markers that suggest adverse effects
VIP (Vasoactive Intestinal Peptide) should only be started, adjusted, or discontinued under medical supervision. This information is for educational purposes only and does not replace professional medical advice. Never stop a prescribed treatment without consulting your healthcare provider first, as abrupt discontinuation may have consequences.
With other peptides
- ✓Prostacyclin Analogs — Complementary vasodilatory pathways may enhance pulmonary hemodynamic improvement in pulmonary hypertension
- ✓Anti-inflammatory Peptides — Combining with other anti-inflammatory agents like KPV may provide synergistic cytokine suppression
- ✓Neuroprotective Compounds — VPAC receptor-mediated neuroprotection complements other neuroprotective strategies in neurodegeneration research
With medications
- !Antihypertensive Medications — Additive hypotensive effects may cause dangerous blood pressure drops requiring careful hemodynamic monitoring
- !PDE5 Inhibitors — Combined vasodilation through different mechanisms may cause severe hypotension
- !Vasoconstrictors — Pharmacological antagonism with VIP vasodilatory effects may reduce therapeutic efficacy of both agents
With supplements
- ✓Multivitamins — Generally safe to take alongside VIP (Vasoactive Intestinal Peptide). Space doses apart if taking oral formulations to ensure optimal absorption.
- ✓Electrolyte supplements — Helpful if experiencing any GI side effects that could lead to dehydration. Safe to combine.
06 · Effectiveness
How do I know it's working?
Moderate human trials · first signs acute hemodynamic response (minutes to hours)
Evidence level
Moderate human trials
(Phase 1-2)
How it works
VIP is a natural messaging molecule in your body made of 28 amino acids that works like a chemical messenger throughout your nervous system and digestive tract. It tells your blood vessels to relax and widen, increases blood flow, and helps regulate your stomach and intestines. When VIP levels drop, it can cause problems with digestion, gut function, and blood pressure control.
Vasoactive intestinal peptide (VIP) is a 28-amino acid neuropeptide that belongs to the secretin/glucagon superfamily and acts as a ligand for VIP receptors (VPAC1 and VPAC2), which are G-protein coupled receptors that activate adenylyl cyclase through Gs proteins. VIP-mediated activation of VPAC receptors increases intracellular cAMP, leading to activation of protein kinase A (PKA) and phosphorylation of CREB transcription factors. This signaling cascade produces vasodilation through relaxation of vascular smooth muscle, modulation of immune cell function through upregulation of anti-inflammatory cytokines (IL-10, TGF-beta), and regulation of gastric and pancreatic secretions. VIP is expressed in neurons of the enteric nervous system, sympathetic ganglia, and throughout the CNS, particularly in the hypothalamus and hippocampus, making it important for neuroimmune regulation and cognitive function.
What to expect
Acute Hemodynamic Response (Minutes to Hours)
What you might notice
- •Rapid onset vasodilation, blood pressure reduction, and smooth muscle relaxation;
- •immediate hemodynamic effects with IV administration
What's normal
- •Initial response to VIP (Vasoactive Intestinal Peptide) is beginning at the cellular level
- •Different individuals experience VIP (Vasoactive Intestinal Peptide)'s onset at different rates
- •Transient systemic effects from initial VIP (Vasoactive Intestinal Peptide) exposure are common
What's next
- →Maintain consistent VIP (Vasoactive Intestinal Peptide) administration as prescribed
- →Document subjective effects and physical markers daily
- →Schedule a check-in with your provider about initial observations
Anti-Inflammatory Phase (Days to 1 Week)
What you might notice
- •Significant reduction in inflammatory cytokines (IL-6 reduction by Day 3 in clinical trials);
- •improved oxygenation in respiratory conditions
What's normal
- •VIP (Vasoactive Intestinal Peptide) is achieving sufficient receptor engagement
- •Initial mechanism of VIP (Vasoactive Intestinal Peptide) is taking effect
- •Early transient effects from VIP (Vasoactive Intestinal Peptide) administration are resolving
What's next
- →Maintain consistent VIP (Vasoactive Intestinal Peptide) administration as prescribed
- →Document subjective effects and physical markers daily
- →Schedule a check-in with your provider about initial observations
Clinical Benefit (1-8 Weeks)
What you might notice
- •Sustained immunomodulatory effects;
- •improved survival outcomes in ARDS at 60-day follow-up;
- •maintained hemodynamic improvement in pulmonary hypertension
What's normal
- •Full therapeutic effects of VIP (Vasoactive Intestinal Peptide) are well-characterized at this point
- •Maintenance of VIP (Vasoactive Intestinal Peptide)'s therapeutic effects is typical
- •Tolerance patterns with VIP (Vasoactive Intestinal Peptide) are generally stable over months
What's next
- →Comprehensive assessment of VIP (Vasoactive Intestinal Peptide) efficacy should be conducted
- →Discuss long-term continuation, cycling, or protocol modifications
- →Continue regular monitoring of relevant biomarkers or symptoms
Signs it's working · Treatment Response
- ✓Improvement in the primary symptoms or condition being treated
- ✓Positive changes in relevant lab values or clinical markers
- ✓Consistent, stable response to VIP (Vasoactive Intestinal Peptide) over time
- ✓Reduction in symptom frequency or severity
Signs it's working · General Well-being
- ✓Improved energy levels and daily functioning
- ✓Better quality of life related to the treated condition
- ✓Manageable or absent side effects indicating good tolerance
- ✓Positive feedback from healthcare provider during check-ups
Not seeing results? Common reasons
- •Not at therapeutic dose yet—initial doses are for building tolerance, not maximum effect
- •Insufficient time at target dose—most compounds need several weeks to show full benefits
- •Inconsistent dosing schedule—regular, consistent use is crucial for optimal results
- •Individual variation in response—genetics, metabolism, and other factors affect outcomes
- •Underlying conditions or medications interfering with absorption or effectiveness
- •Improper storage leading to degraded product—always verify proper storage conditions
Key research
07 · Questions
Frequently asked
What is the difference between VIP and aviptadil?+
Aviptadil (RLF-100) is the synthetic pharmaceutical formulation of naturally occurring Vasoactive Intestinal Peptide developed by NeuroRx Inc. It has the identical amino acid sequence as endogenous VIP but is produced synthetically for clinical administration. Aviptadil received FDA fast-track designation in 2020 for COVID-19-associated ARDS.
How did VIP perform in COVID-19 ARDS trials?+
In a Phase 2b/3 multicenter randomized controlled trial (196 patients across 10 US hospitals), IV aviptadil showed a 2-fold improvement in 60-day survival (OR 2.0, p=0.035) and a 10-fold survival improvement in mechanically ventilated patients (p=0.031). While the primary endpoint was not significant, survival signals were robust with significant IL-6 reduction by Day 3 and no serious drug-related adverse events.
Is VIP the same as PACAP?+
No, VIP and PACAP are related but distinct peptides in the same superfamily. VIP is 28 amino acids while PACAP-38 is 38 amino acids. They share VPAC1 and VPAC2 receptors but PACAP additionally activates PAC1 receptors with high selectivity. VIP has more prominent vasodilatory and GI effects, while PACAP is more focused on neuroprotection.
Why is VIP given by inhaler for lung conditions?+
Inhaled VIP delivers the peptide directly to pulmonary vasculature and airway smooth muscle, maximizing local therapeutic effects while minimizing systemic side effects like hypotension. Studies have shown that inhaled VIP at 67-300 mcg/day is well-tolerated with minimal systemic absorption, making it an ideal route for pulmonary hypertension and sarcoidosis.
What are VIP's neuroprotective properties?+
VIP provides neuroprotection primarily through VPAC2 receptor-mediated pathways including attenuation of microglial activation, shifting cytokine profiles from pro-inflammatory to anti-inflammatory, and preventing neuronal cell body degradation. It has shown protective effects in animal models of Parkinson disease (MPTP/6-OHDA) and Alzheimer disease, though clinical translation is still in early stages.
Is VIP being developed for any other conditions?+
Beyond ARDS and pulmonary hypertension, VIP is being investigated for inflammatory bowel disease, type 2 diabetes (via VPAC2-mediated insulin secretion), sarcoidosis, pulmonary fibrosis, and emerging antiviral applications. VPAC2-selective agonists are also being developed as novel hypoglycemic agents for diabetes treatment.
08 · Further reading
History & related research
History · since 1970
A 28-piece messenger that tells blood vessels and lungs to relax and heal
VIP is a 28-amino-acid peptide discovered in 1970 by Iraqi-American scientist Dr. Sami Said and Swedish researcher Viktor Mutt.
Read the full history of VIP (Vasoactive Intestinal Peptide)