To begin with, it's pronounced PIES like apple PIES but you have to say the letter "F" first.
FPIES stands for Food Protein-Induced Enterocolitis Syndrome. The way I explain it is that my kid has food allergies similar in severity to one with a peanut allergy, except to almost everything. I say it that way because when people think of an allergy they think of a rash. Then they think that it might be ok if Bronsen just has a "little taste" of something he's not supposed to have because maybe then he won't even get a "rash." WRONG.
FPIES (so we are going to get all techical right now) is actually a non IgE mediated reaction in the gastrointestinal system to one or more "trigger" foods typically found in infants and young children.
Traslation = FPIES is not a regular food allergy, like when you go to the allergist and they prick your arm. It's not something treatable with Benadryl.
FPIES reactions involve: vomiting, diarrhea (sometimes bloody or mucousy) and can eventually and quickly lead to lethargy, dehydration and shock. (Some children with FPIES have more symptoms that these listed.)
Translation = usually within 2 hours after the trigger food is consumed a child will start to present sypmtoms. It all happens very fast. Lots of vomiting and diarrhea quickly lead to dehydration.
So here's another deal. Kids with FPIES aren't any more likely to have regular food allergies than kids without FPIES. Strange but I think a lot of kids with FPIES do have regular food allergies as well as FPIES. FPIES is most often treated by an Allergist.