Positives

• A patient in the MCAS support community reported cyproheptadine helped them “in a very similar way that cromolyn sodium does,” particularly for GI MCAS issues Inspire.
  
  
• Patients commonly use cyproheptadine off-label for MCAS-overlap Long COVID, finding it useful for the appetite, sleep, and migraine-overlap subsets where standard non-sedating antihistamines aren’t enough patient.info.
  
  

Negatives

• One patient reported that cyproheptadine caused “very strong side effects” that were particularly detrimental to their brain function, leading them to discontinue Inspire.
  
  

Hurdles & Side Effects

• Patients commonly report drowsiness, dizziness, dry mouth, and increased appetite (cyproheptadine is sometimes used as an appetite stimulant); the sedation profile makes it more useful at bedtime than during the day WebMD.
  
  
• Cyproheptadine is prescription-only in the US (generic, ~$15-30/month), commonly prescribed by allergists/immunologists familiar with MCAS but unfamiliar to most primary care doctors for this off-label use patient.info.