I'm not a doctor, but let's just say that I've learned a thing or two about allergies over the years. The things I have learned lead me to believe that allergies are essentially a massive immune system malfunction. Allergic response occurs when the body determines that a usually benign substance (like milk) is hazardous. The immune system builds up antibodies to the benign substance, and on the next exposure, the body responds. Whether the response is minor (a few hives) or dramatic (anaphylaxis) isn't relevant for the purposes of this discussion, the point is that the immune system (which is supposed to fight infections) is waging the wrong war.
So if allergies are essentially an auto-immune system disorder, how do they relate to other auto-immune disorders? Are people with allergies more likely to develop things like rheumatoid arthritis, Graves' disease, PANDAS, etc.? If so, how much more likely? Is it likely enough that people with allergies ought to be educated about other auto-immune disorders so that symptoms will be noticed and early diagnosis is more probable?
It's commonly believed that asthma, eczema and allergies are genetically linked, meaning that if the parents each have at least one of those conditions, then the children are likely to also have at least one of those conditions. Furthermore, children won't necessarily have the same condition as the parents. Does this mean that anyone with asthma or eczema is also more like to develop other auto-immune disorders?
And think about this: aren't most people allergic to something these days? So if most people have an allergy of some kind, does that mean that most of us are walking around waiting for the next auto-immune disaster to strike?
If the majority of people have an increased susceptibility to auto-immune disorders, then that's the new normal. Or maybe this is how we've always been. Maybe humans were never meant to eat such a wide variety of foods, travel to such a wide variety of places, and be exposed to so many potential allergens over a lifetime. Maybe we haven't yet adapted to our new mobility. But maybe we still can.