Do you have allergies to tiny amounts like in allergy testing if first exposure?

Exposure required: Previous exposure to the allergen or at least a very similar allergen is required to have a reaction to subsequent exposures. This is because your immune system begins making allergic (ige) antibodies after your initial or sensitizing exposure making a reaction possible on later exposure.

Not so much: You can't be allergic to something until you're exposed to it. On the other hand, we've all been exposed to stuff we might not have known about! i had a patient who nearly died from exposure to peanuts, and she had actually been trying to avoid them her whole life! (she was raised with a sister who was also deathly allergic) turns out it was probably bottled spaghetti sauce that exposed her.