Fixed (immediate) food allergies: When an immediate food reaction occurs, symptoms occur within hours of ingestion. Symptom onset is rapid and may include tingling of extremities, wheezing, coughing, tightening of the throat, nausea, abdominal cramps, and diarrhea. Sometimes in cases where nuts, shellfish and fish have been eaten anaphylaxis may occur. Blood testing (i.e., RAST test) is typically used to verify fixed food allergies. Approximately 5 to 15 percent of food allergies are of the fixed variety.