Sorry for the unsolicited train of advice, but I have some experience with this. Make sure you have loads of benadryl too, and prednisone. If they have serious food allergies they probably have this in their kit and know how to use it. Sometimes, depending on the reaction, it can be more effective than epi. Taking preventative OTC allergy meds is useful too.
I am a river, babe - I've got plenty of time, I don't know where I'm going, I'm just following the lines..... - "We are water" by Shaye