I dunno I am not sure they can but as a person who is allergic we kind of already know what we are allergic to so we usually avoid foods that can cause a reaction. I have been allergic to peanuts for example since I was 8 years old and I have always avoided it in the shops. Even trace amounts of peanuts can cause an anaphylactic reaction in me. When I first got an allergic reaction I went to the hospital with my mom. They treated the immediate symptoms and then sent me to a pediatric allergist. He prescribed a set of tests to figure out what else was I allergic to. We went to a private lab that tested me (if you guys need to get tested you can check them here:
https://www.intolerancelab.co.uk/intolerance-2). In about a week I knew all the allergens I had a reaction to and it helped me have a safer life. I have been okay for the past few decades, so I feel like for anyone who's allergic to be aware of their condition and to just be careful.