Why am I allergic to the allium family of vegetables?

It's not a particularly common allergy and I wonder whether she's had formal testing against that. All those plants are quite irritating in their own right. If I peel an onion my eyes and nose start to water, which is a bit like what you get with an allergy, but it isn't really an allergy that is there. She may or may not have had this proven by a proper laboratory test or a skin test.