That allergist is simply
wrong regarding food allergens producing a particular allergic reaction symptom.
S/he may be convinced that some allergens produce "typical" symptoms, but research simply doesn't bear that out in population studies of people with allergies. There are allergic symptoms that are the result of mast cell degranulation triggered by IgE, and there are allergen-specific IgE in an allergic person's bloodstream. Beyond that, it's a mixed bag mechanistically. Period.
Some allergens are far more likely to provoke
anaphylaxis than others-- for example, fish, shellfish, nuts and seeds-- and among those, there are individual allergens that are more likely to produce spectacular anaphylaxis with vanishingly small traces... yes.

But it isn't EVER as simple as saying that "peanut produces breathing difficulty." Or that "egg produces hives and swelling." Maybe in
one person, it does, at least some (most) of the time. But in another person, maybe not. If it were that simple, then doctors would have a much easier time predicting which patients were truly at risk of fatality from food allergy. Currently, the best they can do is predict who is at elevated risk for
anaphylaxis on the basis of the allergen's identity and patient history. So someone like YKW's son
needs epinephrine even though he's allergic to wheat, which is mostly
not an anaphylaxis trigger. In his case, what is true for "most" patients is simply irrelevant because he has anaphylaxis history with the allergen.
This is why I'm extremely clear about the fact that my own orange allergy is probably OAS and not a primary allergy-- and that I would
never take risks like that with shellfish, because that one can produce unpredictably severe reactions from traces, at least in my own individual experience. For someone else who has an IgE-mediated reaction to oranges, that could well be the case and my method of managing my allergy would be entirely insufficient (and dangerous).
I
promise that we're really just trying to help, honest.

I sure love how oranges smell. <sigh> I
wish I could eat the real thing. I hope that is true for you-- if so, I sincerely hope that you'd enjoy one for me sometime.
One last note (just in general, and not specific to Sn+Sn); It is REALLY important, when dealing with possible
food allergies, to make certain that the person you are seeing
is an M.D. and not an OD or ND. Also important; do enough research on current best practices at AAAAI (and FAI/FAAN) to know whether or not the person who sees you is offering current advice that tallies with developments over the past 4-6 years. Much has changed in the thinking regarding testing, diagnosis, and management in that time. There are also emerging allergens as new seeds/oils begin to be used more widely. Sunflower, for example, is a much more common allergen than it used to be, and it is-- like other seeds and nuts--
super-potent in that they can cause anaphylaxis in very small quantities. HTH someone, even if Sn+Sn already knows all of that.
