How long can it take for a food allergy to manifest itself to you?

Food allergy: Many adults don't have a classic food allergy but rather a food intolerance. Thus a true allergy usually occurs withing 30 minutes but may have a delayed response 6 to 8 hours later. An intolerance is more unpredictable.

Define "allergy": The body can have a variety of responses from life threatening anaphylaxis on one end to hives or irritable bowel syndrome with diarrhea. The anaphylaxis issue could show up within minutes, hives days or IBSD may be intermittent. There is also overlap with food intolerance, where you aren't allergic, but don't digest it & are irritated by it. With some the vague effect is unrecognized for yrs.