The methods used to diagnosis egg allergies are very similar to those used in other food allergies. It can be relatively simple to diagnose an egg allergy when eggs are already a suspected allergen trigger. However, most people with egg allergies react to egg proteins within other foods. As a result, diagnosis may be more complicated.

In order to diagnose egg allergies, a physician will perform a physical exam and collect the patient’s medical history. The most basic question a physician will ask is whether an individual has a consistent reaction to eggs each time they are consumed. Other questions may focus on frequency of reaction, timing of symptoms after eating a particular food and family history of allergies and other conditions (e.g., asthma, eczema).

To be sure that eggs are the culprit, a physician will often administer one or more of the following tests:

• Skin test. During these tests, egg extracts are introduced to a portion of the skin through a scratch, prick, injection or patch The appearance of redness or swelling in the test area indicates an allergic response.. This test can be too dangerous to use on highly sensitive individuals.
  
  

  
  
  

• RAST (radioallergosorbent test). This type of blood test allows a laboratory to directly test a blood sample from an individual in an attempt to detect antibodies that correspond to an egg allergy. This test can be used on those people who have reactions that are too sensitive for a skin test. The RAST test is also a good option for infants, or individuals with skin disorders such as eczema.
  
  
• Elimination diet. This test involves removing eggs from an individual’s diet for several weeks to see if allergic reactions persist. If the reactions do indeed stop, it can be presumed that eggs were the culprit.
  
  
• Oral 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. 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.