I had seemingly random late night episodes of urticaria/ angioedema (mainly hands and feet) a few years ago. At the time I was researching histamine intolerance because I was also flushing frequently with rosacea and/ or dry coughing/ mild wheezing. I was horrified that anything aged or fermented was off the menu, plus alcohol … all my very favourite things!
I tried an OTC antihistamine (cetirizine), mast cell stabiliser (quercetin), probiotics (capsules not fermented foods), magnesium citrate tablets. *All with my GP’s knowledge*.
Best results by far was overhauling my entire diet and lifestyle to be more anti-inflammatory/ gut healthy/ immune calming. Massively less alcohol and starchy carbs, massively more oily fish/ non-starchy vegetables/ low sugar fruits/ certain seeds and nuts, better sleep patterns (epic fail on stress management tho).
I now believe the triggers (most never identified so idiopathic) were ‘the straw that broke the camels back’ to a body that was in a chronic state of inflammation. Note that histamine is released by the immune system as a normal part of the inflammatory process.
I can now drink alcohol, eat mature ripened cheeses and aged air dried ham without major issue. Last rosacea flare was from a minor dental infection (= inflammation) last wheezing/ urticaria/ angioedema episode from exposure to a huge amount of dust. So not random/ idiopathic!
If you can get your immune system calmer and gut healthier, you might find you too can reintroduce some no-nos to a reduced histamine diet. The problem with some of these plans is that they can be very restrictive/ lacking in variety so nutrient imbalances are a risk. I increased oily fish (fresh/ canned/ smoked) in my diet because I needed the omega-3s and vitamin D more than I needed to eliminate any histamine.
HTH!