The wording of your question makes it almost impossible to answer in any meaningful way, at least from my reading of it, for one pretty big reason: if you're stipulating the time period as being pre-discovery/understanding of allergies and allergic reactions, the historical sources would, by definition, have been just as ignorant in the matter as the king and his attendants. The best we can hope to do is speculate based on the accounting of the manner of death, but that's hardly going to provide any concrete answers.
So, like, I had an allergic attack due to people not following the rules and I've had to delete nearly every answer in this thread.
Please, no more weak answers or guesses. Remember the rules. As was explained in the excellent recent meta post on "What it means to post a good answer in /r/AskHistorians": If you're choosing to answer a question in /r/AskHistorians, there are three questions you should ask yourself first in turn:
Do I, personally, actually know a lot about the subject at hand?
Am I essentially certain that what I know about it is true?
Am I prepared to go into real detail about this? And also:
Do not post hopelessly incomplete answers based on a skimming of a Wikipedia article just because nobody has yet replied after a few hours.
I'll have a go at asking this one. Have there been any instances in which a head of state, while suffering what appears (to us) to be an allergic reaction, punishes someone in the in the mistaken belief said suffering was in fact the result of a botched assassination attempt?
Something better to find out would be: When did we learn about allergies? Was there crossover during medieval times when we knew this or did we find out about allergies after the medieval times?
Another interesting question, were allergies more prevalent now than they were back then?