And if the allergy manifests itself only some time after the allergen enters the body (therefore it is difficult to determine what it is), then you probably should not be afraid of anaphylactic shock?
This is all strictly individual, but for many people it can be very dangerous. Anaphylactic shock, Quincke's edema are deadly conditions that require immediate medical attention.
So dangerous that in many civilized countries allergy sufferers prone to Quincke's edema always carry an injector with adrenaline with them, and are instructed at the first symptoms of edema immediately inject yourself and call an ambulance. In that order. This is such a dangerous condition that in countries where you cannot buy anything stronger than aspirin in a pharmacy without a prescription, allergy sufferers trust a potent substance that he must inject BEFORE the ambulance arrives.
For example, you can die. Anaphylactic shock is no joke. Please note that some food items, such as chocolate, are often written to contain traces of peanuts. Peanuts are a very strong allergen, for some people even very small doses are deadly.