Positives

• One patient on a Health Rising thread reported that intranasal insulin gave them "the fog-free brain of my younger years" and that they settled on once-every-three-days dosing, per a Health Rising forum discussion.
  
  
• A scoping review found patients with persistent post-COVID olfactory dysfunction described meaningful smell recovery on intranasal insulin protocols, per a PMC scoping review.
  
  

Negatives

• Patients commonly describe mild to moderate headaches in the first weeks, with some needing to alternate nostrils to reduce nasal irritation, per a Health Rising forum follow-up thread.
  
  
• Effects can fade after weeks of consistent use and the dose-response is unpredictable from patient to patient, per the same Health Rising forum discussion.
  
  

Hurdles & Side Effects

• No FDA-approved intranasal insulin product exists for cognition, forcing patients to either compound it or work around devices designed for systemic insulin, per a JAMA Neurology trial report.
  
  
• Patients need a willing prescriber and an atomizer or precision delivery device, since standard nasal sprays don't reliably target the olfactory cleft, per a PubMed scoping review.