About six years ago, I had my first hives attack and went to the ER. I made an appt with a specialist who told me it might be virtually impossible to find out what combination of things triggered my attack. He said that if it happened again and I wanted to, I could try a battery of tests to try and figure it out. He gave me a prescription for an EpiPen in case it happened again and it would take to long for me to seek treatment.
Since then, I have one or two attacks per year. I've been able to figure out it happens when I'm dehydrated, under stress and have ususally been cleaning then eat something that triggers the hives. I now know that, for me, as soon as my scalp starts itching as well as the inside of my left elbow, I should take a Benadryl.
My last attack happened after having had Kraft Mac & Cheese and green beans for dinner. In an attempt to narrow down my problem further, I had both the Kraft and green beans as left overs the next day. Nothing. No reaction at all.
I would prefer to know what I'm allergic to but, unless my problem gets worse, I've figured out how to manage it. If the Benadryl were to fail, then I have the EpiPen as a backup.