Food Allergy Reactions
Reactions that may indicate a food allergy are itchy mouth, "fullness" in the throat, shortness of breath, an intense red, itchy rash all over the body, difficulty breathing, and vomiting. In a worst case scenario, as I mentioned above, a food allergy reaction can result in death. Although severe reactions do occur, milder food reactions are more common. Common mild allergic food reactions would be red, itchy skin with hives or eczema (also called atopic dermatitis), and another type of itchy skin rash, which can be caused by eggs and many other foods. Some of my patients with mild food allergies have also complained of fatigue or increased nasal irritation.
Diagnosis
When I see someone who has symptoms of a food allergy, I pay close attention to the time that elapsed between the consumption of the suspected food and their reaction. Food allergy reactions usually occur within minutes and sometimes within seconds. So when a patient tells me that they ate a certain food yesterday and experienced itchy skin today, it's probably not due to a food allergy.
Sometimes a diagnosis can be made via trial and error, by eliminating a suspected food. If the skin clears up, the food is reintroduced to see if the skin flares once more. If you are attempting such an elimination diet, stay off the offending foods for at least two weeks and add back each food one at a time every three days.