A food allergy is when your immune system mistakes a harmless food as a threat and sets off a false alarm.
Food allergy symptoms include things like a runny nose, hives, wheezing, congestion, vomiting, diarrhea, or lightheadedness.
More severe food allergies can cause anaphylaxis, which can lead to a coma or death.
It can be hard to detect a food allergy because the type of reaction and the intensity of the reaction differ from person to person; but there are a number of tests that can test for possible allergies.