Having a "food allergy" to a particular food means that your body has an adverse immune response (allergic reaction) to a molecule in the food, usually a protein. The allergic reaction is triggered because your body's immune system mistakenly identifies the protein as something harmful.

The most well-known allergic responses are dermatitis (rash), gastrointestinal distress (stomach ache), and respiratory distress, but food allergies can cause an almost unlimited number of symptoms including headaches, fatigue, mood disorders, joint pain and more.

Also, the symptoms can be immediate or delayed, making it difficult to determine which food is causing the allergy.

An ELISA Blood Allergy Test may be helpful in determining if you have any food allergies and what they are.