Immunoglobulin E–mediated allergic responses to food and environmental allergens can cause symptoms ranging from mild allergic rhinitis and rashes to gastrointestinal distress and, most seriously, anaphylaxis. The diagnosis can be difficult, as it relies on complex interplay between patient history and diagnostic tests with low specificity. Adding to the difficulty in confirming the diagnosis is an increased public interest in food intolerances, which can be inappropriately attributed to an allergic response. Treatment of allergic diseases with avoidance strategies and pharmacologic treatments can improve quality of life and control of other chronic conditions, such as asthma and eczema.