I am aware of quite a few ancient and medieval writers discussing seasonal allergies, but how well did people understand food allergies and acute triggers? How did people know to avoid certain foods?
Also, were any deaths attributed to poisoning that we know or suspect may have been allergy-related?
I haven't been able to find the exact source, but there was a paper given on this topic at the 2013 Anglo-American Conference of Historians in London. The author argued that the history of food allergies has been studied remarkably little, and, more interestingly, that there are very few references to food allergies in the medical literature before about 1970. So, this is not to say that they did not exist or that people did not have adverse reactions to particular foods; it is to say that medical science did not pay attention the phenomenon. Whether doctors have recognized pathologies that have been there all along or whether people are in fact becoming more allergic to more things is an open question.
Again, I'm very sorry to not have a specific source but as far as I can tell--for some bizarre reason--the Institute of Historical Research doesn't seem to maintain an easily-accessible database of their past conferences. I'll keep looking to see if I can figure out who it was that gave the paper so that we can track down more research on the subject.
I would like to ask a question related to this for anyone knowledgeable. Did people even have serious allergies before the start of the industrial revolution?