An allergy is a response from the immune system to a particular foreign substance in the body. While this substance is typically harmless to non-allergic individuals, it can cause an adverse reaction in those who are allergic.
This foreign substance is known as an allergen. Common allergens include pollen, dust mites and food items such as shrimp and peanuts.
Allergy tests are used to determine the allergens that the immune system reacts to IgE blood tests will be conducted to identify food and inhalant allergies in particular.