It's a question of risk vs reward. Your body has an extremely complicated and mostly successful system of defence. If a pathogen enters the body and is not att

It's a question of risk vs reward. Your body has an extremely complicated and mostly successful system of defence. If a pathogen enters the body and is not attacked, it may easily kill you, for this reason pathogens, once identified, are always attacked. There is a system that is responsible for identifying threats(lymphocyte), some times this messes up and identifies the wrong thing as a threat. This is easier than you might think because your body makes antibodies(attack living stuff like bacteria but quasi stuff like viruses) and antitoxins(attacks toxins), when the body sees a foreign substance in the blood, it only takes one lymphocyte is misread it as a threat, and boom all-of-sudden your body fights like the devil to kill/remove/subdue that thing. Backing down the response would alleviate some allergy problems, but it would also cause the body to perhaps miss some actually-bad things in your system. It'll be hard to change this, and problem inadvisable, as the system has been tuned over millions of years. The best course of action is probably treating symptoms, or finding targeted and intelligent ways to trick the system into handling these corner cases better.