I have heard of people having sensitivity to onions and also garlic as well. I'm sorry you can't tolerate onions well. That'd be a real pain the way I cook with them.

My son had a very severe reaction to hairy caterpillars when he was little. He didn't even touch one. He touched the area where they had been crawling.

Talking of cats...
one of my cats nearly died from eating tulip leaves.

A relative became allergic to mangoes when she was in her 40's or so. What happened was she helped pick the green ones off the tree because they were making chutney. She got lots of the sap on her. It's a thick, white sap and hard to get off. Anyway, she could never drink tropical fruit juices or of course eat mangoes from then on. A lot of the mixed juices seem to have it in them.