Food allergy is an adverse reaction caused by an abdominal response of the immune system to food allergens. Behaving like recognizing an invader and sending out chemicals to defend against it.
A specialist in allergy and immunology would take a comprehensive clinical history (such as; reaction to the culprit food, diet history, etc.) to guide the selection and tests to perform and interpret the results. The ultimate goal of the allergy test result is to determine the probability of clinical relevant allergy.
Eight types of food can cause 90% of all reactions: egg, milk, peanuts, tree nuts, fish, shellfish, wheat, soy.
Skin prick test provide results in 20 minutes.
Serum testing allows evaluation of patients who cannot stop the routine antihistamines therapy prior to testing. Serum specific IGE techniques are less efficient (results available in about a week) and are more expensive than skin testing.
Once the food allergy is diagnosed the most effective treatment is to avoid the food. Once you have been diagnosed with food allergy, your allergist/immunologist should prescribe an epinephrine auto-injector.
Oral food challenge is the most accurate test to diagnose food allergy. But requires expensive resources, highly trained personnel, and carries the risk of causing an acute allergic reaction.