>If you're allergic to casein, sodium caseinate, etc, you can have a
reaction to some Kosher pareve items, since casein is
considered pareve. That is also the case for some other, milk-derived
items.<

I don't know of any certifying group that considers casein to be pareve.
Pareve foods, by definition, can contain nothing that is meat-derived or
dairy-derived. Perhaps the confusion here stems from other ingredients,
like lactic acid, which are dairy if derived from milk, but can be pareve
if they come from a source other than milk. But casein and the caseinates
are not pareve.

Steve Carper