Do you diagnose MCAS if a patient is concurrently on drugs known to cause non-specific mast cell degranulation?

Yes, MCAS may be diagnosed if a patient is on drugs known to cause non-specific mast cell activation.

The reason for this answer requires a better understanding of MCAS criteria and etiology. In 2022, an expert consortium proposed revisions to the classification of mast cell activation disorders. (Valent et al., PMID 35342031)

This revision split the diagnosis into two conceptual parts: diagnosis of mast cell activation syndrome (MCAS) and subsequent diagnosis of etiology of mast cell activation. ...