I was coming here today to search for this. I'm subbing in a district where a student has this diagnosis. It is horribly debilitating. In spite of seeing all kinds of specialists, they don't have any solid answers on what is triggering her.
The IHP should certainly include any known or potential triggers. Ideally, anyone who works with the student should be an EpiPen delegate although I found this type of anaphylactic event is hard to distinguish from other common illnesses. For instance, in my student's case, she starts off with a cough and progresses into wheezing. Without other symptoms, it looks like asthma. But albuterol doesn't touch her symptoms (she does have an asthma diagnosis).
Some other precautions in place: she has a buddy that accompanies here everywhere. She uses the bathroom in the nurses office. She carries an epipen in her purse. The bus driver is an epipen delegate.
Of course a plan for how to handle a crisis (Benadryl, epipen, etc).
I'm curious to hear anyone else's experience!