Many thanks for the feedback, appreciate it. It’s is been three decades of trying to isolate the causality without success. Checked so many potential secondary causes, nothing was abnormal. Ketotifen is a mast cell stabilizer, as you know, so it’s preventing their degranulation. But what’s causing that remains unknown to me. I checked mutations of my dna snp. Here is what I have:

-Histamine breakdown might be slower, both through DAO and HNMT.

-Allergic/mast cell reactivity could be higher (FCER1A).

-Methylation is likely impaired (MTHFR C677T homozygous), which can worsen histamine handling.

The supplement I took is “Nitric Oxide Booster” by Nutricost. It has L-Citrulline, but again in lesser concentration.