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VIP (vasoactive intestinal peptide) protocol

VIP is a natural peptide that relaxes blood vessels and calms inflammation. A synthetic form, aviptadil, is sold in the UK inside an injection for erectile dysfunction. The nasal-spray use for mould illness (CIRS) rests on one open-label study by the protocol's developer.

Aviptadil (synthetic VIP) is marketed in the UK in Invicorp, an injection for erectile dysfunctionNasal VIP for CIRS is not an approved useFDA lists VIP as under evaluation for pharmacy compounding (list updated May 2026)
ProtocolMixingResultsSide effectsHow it worksSources

The protocol at a glance

The CIRS protocol uses 50 mcg by nasal spray four times a day for at least 18 months, in an open-label study with no placebo group.

Use studiedAmount and schedule
Nasal spray for CIRS (Shoemaker 2013)50 mcg, 4 times a day, for at least 18 months
Erectile dysfunction (Invicorp)25 mcg aviptadil with phentolamine (1 or 2 mg), injected into the penis

Shoemaker R, House D, Ryan J. Health 2013;5:396-401, as described by secondary sources; we could not open the full paper, so the number of people and whether 50 mcg is per nostril or in total are unconfirmed. Invicorp amounts are from a 2008 BJU International abstract.

Community reports

The published CIRS protocol is described as 50 mcg intranasally four times a day for 18 months or longer.

What people say they do, collected from community discussions. Not tested in a trial; shown so you can compare it with the evidence above.

Mixing

No mixing table here: this one is used as a capsule, nasal spray or skin product, or has no human amount to calculate from. The general mixing calculator works for any vial.

What the trials found

No placebo-controlled trial of nasal VIP for CIRS was found. A different use, IV aviptadil in COVID-19 respiratory failure, was tested in a large placebo-controlled trial (TESICO):

0placebo-controlled trials of nasal VIP for CIRS found
461patients analysed in TESICO; no significant benefit up to day 90
38% vs 36%died by day 90, aviptadil vs placebo (no significant difference)
63% vs 56%had the main safety outcome by day 5, aviptadil vs placebo (not significant)

Lancet Respir Med 2023;11:791-803 (TESICO, PMID 37348524, NCT04843761); stopped for futility. Shoemaker 2013 is the CIRS source. The main safety outcome was death, serious adverse event, organ failure, serious infection or grade 3-4 adverse event up to day 5.

Side effects

  • In TESICO, the combined main safety outcome occurred in 63% with aviptadil and 56% with placebo. The gap was not statistically significant.
  • The CIRS study reports no drop-outs from side effects in about 18 months, but it had no placebo group and was run by the developer of the protocol.
  • Long-term safety of nasal VIP outside that study is not established.

How it works

Widens blood vessels in the lungs

In an open-label 2003 study of 8 people with primary pulmonary hypertension, inhaled VIP lowered pressure in the lung arteries and raised heart output (Petkov, J Clin Invest).

Sources

  • Shoemaker R, House D, Ryan J. Health 2013;5:396-401, doi 10.4236/health.2013.53053 (described via secondary sources)
  • Petkov V et al. J Clin Invest 2003 (VIP in primary pulmonary hypertension), PMID 12727925
  • TESICO / ACTIV-3b aviptadil trial, Lancet Respir Med 2023, PMID 37348524, NCT04843761
  • MIMS 2015 (Invicorp UK launch); NHS Wales AWTTC appraisal of aviptadil/phentolamine
  • FDA 503A bulk drug substances list (Category 1: Vasoactive Intestinal Peptide), updated May 14 2026