Answer the following question given this paragraph:   Food allergies occur when the immune system reacts to substances in food as though they were harmful “foreign invaders. ” Foods that are most likely to cause allergies are pictured in Figure below , and include nuts, eggs, grains and milk. Symptoms of food allergies often include vomiting and diarrhea. Symptoms of food allergies include itching and swelling of the lips and mouth. More serious symptoms include trouble breathing. In some instances, a food allergy can trigger anaphylaxis, which is an extremely severe reaction. Emergency medical treatment is critical for this condition, which left untreated, can lead to death.   Q: What is an extremely severe food allergy reaction?   A:
anaphylaxis