Shop online for allergy tests to help identify common environmental, respiratory, or food allergens affecting your immune system. These allergy blood tests measure the levels of IgE (immunoglobin E) antibodies your body produces when exposed to a substance. Once you purchase a test, it's easy to schedule an appointment at one of 2000+ Quest Diagnostics locations nationwide. You'll get fast results online and have the option to discuss them with an independent physician at no extra cost.