Mostly yes. Food protein induced enterocolitis syndrome (fpies) is a "non-ige" allergic reaction to proteins found in infant formula (cow milk or soy) and in some baby foods. The prognosis is good, with many children outgrowing it by the time they are three years old. However, they don't outgrow all the allergies at the same time, so testing by allergists is needed to find out which foods are safe to try.
Nearly all. Fpies is a difficult diagnosis, done basically by observation of severe symptoms and relief with diet elimination. Included in the syndrome description is resolution with age. Patch testing use is limited. Fpies is diagnosed in early childhood (<2 years). In teenagers, careful investigation to rule out other entities should be performed before fpies is diagnosed.