I can't tolerate chemicals in my food. I have a migraine all the time and if I eat cured foods, lunch meats, yellow cheeses, or MSG amoung many other things, I get a horrible headache that lasts three or four days. Only Imitrex will relieve the pain at all.
The doctors tell me it's not an allergy, but a reaction to the chemicals. I have had three sinus surgeries just so I can breathe through my nose. It still swells shut at times. So far the only help I have found at all is to avoid the things with chemicals in them. That is so hard to do as so many aren't labeled.