Allergy Testing vs Food Intolerance Testing: Which One Do You Need? Understanding Symptoms, Diagnosis, and Trusted Methods Food allergy and food intolerance can produce similar discomfort but arise from different biological processes and need different approaches to diagnosis and care. A food allergy is an immune response—commonly IgE-mediated—that can cause rapid, systemic symptoms and requires emergency planning and avoidance. Food intolerance is usually due to digestive or