The first step a physician is likely to take in the diagnosis of a food allergy is to create a detailed medical history and dietary history of the patient. However, it is often difficult to obtain a quick diagnosis for this type of condition because the symptoms of a corn allergy mimic those of other allergies (e.g., pollen, mold).

By gathering basic information, a physician can get a better idea of where to proceed with further evaluations. This may include attempts to identify the specific allergen to which the patient is sensitive. Such procedures are not definitive, but can provide information that is relevant to the patient’s condition and useful in designing treatment plans. These measures may include:

• Skin test. This test involves pricking the patient’s skin with food extracts. The skin will react with redness and swelling for those extracts capable of eliciting an allergic reaction when consumed. This type of test provides results that are accurate; however, the results will vary depending on the food being tested.
  

  

   
• RAST (radioallergosorbent test). This type of blood test allows a laboratory to directly test a blood sample for antibodies that correspond to specific foods. While less sensitive than a skin test, it can be used on individuals who have reactions too severe for a skin test.
  
  
• Oral food challenge. Also called the double-blind food challenge, this is considered the most effective way of determining the cause of a food allergy because it supplies the most convincing results. Different foods are placed within capsules to hide their identity. Neither the patient nor the physician knows which capsule contains the suspected allergen. The patient consumes the capsules and the physician looks for signs of an allergic reaction. This type of test is time-consuming and difficult. It is often reserved to confirm suspicions that a patient's symptoms are not caused by a food allergy. This type of test should only be performed in the presence of a physician who can treat anaphylaxis.
  
  
• Elimination diet. This process involves removing suspect foods from a patient’s diet to see if the allergic reactions persist. Foods are removed on a trial-and-error basis for a period of time. The results of the diet make it easier to confirm, rule out or permanently remove a problem food.