Interesting to see the different ways hives pop up for people. :)
For me, I got my first case of hives when I was 10. They came from eating a roll of Wintergreen Lifesavers. Yeah. Apparently, eating too much of anything in the mint family (peppermint, spearmint, wintergreen, creme de menthe, etc.)--the REAL oil--was what triggers hives all over the body for me. If I eat one small piece of creme de menthe cake (a Xmas/holiday favorite in my family), I'm usually okay; if I decide to eat a second small piece, I can start feeling the warmness and tingling and the start of itching, which I then know means put down that piece of cake right now! LOL No more cake.
As an adult I get hives between my thighs from cold weather. Usually from cold and friction (shoveling snow, raking leaves in the fall, playing outside when it's very cold with my daughter), but I've also developed hives from just having a cold bottle of pop sitting between my legs in the car. Yeah. And once I was at a water park in the summer. It was overcast, windy, and chilly, especially if you'd been in the water. I'd borrowed some spray-on suntan lotion from my friend, so I'm not positive if it wasn't also a reaction to that (I'd never used it before), but it didn't take long for me to break out in these huge white, raised hive bumps all over my body. Some were bigger than a 50 cent piece. I had to get dressed, take a Claritin, and stay out of the water for the rest of the day in order for them to go away. That was the worse case of hives I've ever had. The Allergist said my hives are all IO and seem to be chiefly related to weather/cold.
But I've also discovered as an adult that I have a casein allergy (cow's milk), a severe intolerance to soy and gliadin, and about 20 other food intolerances. Since I've had to give up eating a lot of these foods, my incidences of hives have also dramatically declined. So I'd say many cases of hives are probably also linked to food problems.
Many people fail to realize that the biggest organ in our body is our skin, and toxins and other problems that the body is trying to eliminate are eliminated through the skin. That's why people have acne, psoriasis, eczema, roscea, etc. Many conventional doctors never make the connection between toxins/food allergies and skin problems; they just prescribe drugs. The drugs only mask the problem; they don't get to the root cause or make the problem go away.