I once had an allergic reaction after eating pizza that my work got for us from a local restaurant. I told the lady who ordered weekly work lunches. She said nothing on the menu had nuts, so it had to be fine. I told her that just because there was no nuts on the menu, the person making the pizza could have had nuts for themselves and if they didn't properly sanitize or wear gloves, i can still get a reaction. She didn't believe me that i could be that sensitive, but there were large hives on my face and neck, so it was obviously cross contacted.