Objective: To describe the clinical characteristics of food protein-in
duced enterocolitis syndrome (FPIES), a symptom complex of severe vomi
ting and diarrhea occurring several hours after the ingestion of parti
cular food proteins in infants. Study design: Retrospective review of
a referral population. Results: Sixteen patients had typical FPIES; 11
reacted to milk, 11 to soy, and 7 to both. Mean age at diagnosis was
7 weeks for milk reactivity and 8 weeks for soy reactivity. Two patien
ts also had rice- and pea-induced FPIES. Among 14 patients who were fo
llowed up for a median period of 25 months, loss of sensitivity to mil
k occurred in 6 of 10 patients and loss of sensitivity to soy occurred
in 2 of 8. Six additional cases of FPIES were considered atypical: 1
patient had late-onset disease caused by poultry, and in 5 patients Ig
E antibody to milk or soy developed. During supervised food challenges
with milk and soy, the peripheral blood neutrophil count rose over 35
00 cells/mm(3) in 9 of 10 positive challenges and did not rise above t
his value in the 7 negative challenges. Emergency treatment was requir
ed in 62% of challenges. Conclusions: Although most patients with FPIE
S are infants reactive to milk and/or soy, this diagnosis should be co
nsidered in older children and for other foods. Food-specific IgE sens
itivity may develop in some patients. Standardized food challenges are
helpful for diagnosis and follow-up.