When our son was authoritatively diagnosed with anaphylactic food allergies one of the most helpful pieces of advice our md gave to us was "You will not hurt him if you give him the epi-pen and it turns out he might not have needed it." In other words, our protocol is "give it if it seems it might be needed." For our son, the worst that would happen would be some flushing, heart racing and other adrenaline symptoms. Our doctor said "You won't kill him by giving him the epi-pen. But by the time you are SURE he needs it, he might die without it."
We have a treatment action plan on file with the school, which we update every time there is a medication change and which we train all his teachers and the cafeteria staff on every year the day before school starts. We cover everything, including who will transport to the ER if both of our town ambulances are on other calls (SMALL town).
Now that he's in high school we actually have 6 epi-pens stored in different parts of the school, and "mini action plans" with those teachers when Graham is scheduled for their part of the building (to prevent an epi from being locked up in a desk when it might be needed).
It paid off twice--several years ago he got a single shred of cheese in the lettuce on taco bar day. They had changed the cheese color to white w/out informing us, and weren't following their own protocol that the lettuce and cheese weren't supposed to be next to each other. The nurse gave the first epi in a room off the cafeteria (as most of you will know, this involves pulling down the pants for optimal administration) while the vice principal summoned the ambulance. The EMTs gave the second epi.
Our rule with the school is DEAL WITH THE MEDICAL EMERGENCY FIRST AND CALL THE PARENTS LATER.
A few years later he ate a pillsbury roll at home with a small amount of whey. His allergies had been improving and he'd been able to consume very small amounts of whey w/out ill effects. Something went haywire in his system and he reacted big time about 2 hours after ingestion while at school. The product he ate he'd been eating successfully for 2 years. The regular nurse--and the vice principal who coordinates the plan--were both out of the building, but the rest of the team swung into action, gave the epi and got the ambulance and he lived. Thank God we'd rehearsed "what if" scenarios.
When he was little we used to give benedryl because, frankly, it made him calmer and sleepier, and less agitation means the hives don't progress so quickly. The allegra he's on year-round seems to have some small effect in keeping the hives/blotching down--but the antihistimine does not affect either severe gastric reactions or anaphylactic ones.
Some of what we've learned is the unpredictability of reactions: sometimes it's gastric, sometimes respiratory; sometimes instant, sometimes hours later, sometimes more mild, sometimes severe. In general, if your child has had mild reactions, you need to be prepared that they might escalate.
Now that he's 17 we have a new worry. He ended up hospitalized once as a child because a babysitter ate a cheese doodle and then touched his face without washing her hands. Now that he's to the point that he might be thinking about kissing, we've had to face that if he were to kiss someone who'd just had a slice of pecan pie, he might very well die, even with an epi. We are hoping that all these years of assertiveness training, and helping him to function independently won't fly out the window the first time the hormones are flowing and he needs to ask some hot chick to stop and brush her teeth.
If anyone would like a copy of the action plan we execute with our school, which includes as succinct a description as I could craft of the symptoms which indicate an anaphylactic onset, please PM or email me and I'll be happy to send it to you. And--again, I'll echo that the food allergy network saved our son's life, multiple times. The kits they have for school nurses and other resources have been invaluable for us. We have worked with world class allergists over the years, yet food allergies are often a mystery to them. There have been many times when I've been the more informed partner in the parent/MD relationship, and have had to keep the ball rolling in treatment options.
Those who are dealing, in particular, with PA should be watching the trials for anti-IgE drugs, which show some promise, not at curing PA, but permitting the threshold before having a life-threatening reaction to expand from 1 or 2 peanuts to as many as 24.
Like most of you, I have permanently ground teeth from fielding all the "maybe he'll outgrow it" assurances, but I am so grateful to be raising a child now, rather than 2 decades ago. Maybe by the time our kids are frantic parents trying to arrange a theme-park dinner outing there will be a cure and this will all be an ancient nightmare.
Boy am I long-winded, sorry. 
Peanutallergy.com has some interesting info also.
