Overview
A food allergy is an immune reaction to a specific food. The body mistakenly treats part of that food, usually a protein, as dangerous and releases chemicals that cause symptoms. Food allergies are not the same as food intolerances, which do not involve the immune system in the same way. Reactions can happen within minutes, but sometimes they start later.
Key Symptoms
Symptoms can include itching, hives, swelling of the lips or face, stomach pain, vomiting, diarrhea, coughing, wheezing, throat tightness, dizziness, or fainting. Some people have mild symptoms at first and then get worse quickly. A severe allergic reaction is called anaphylaxis and can affect breathing and blood pressure. Symptoms may not be the same every time.
Causes and Risk Factors
Food allergies happen when the immune system overreacts to a food. Common trigger foods include cow's milk, eggs, peanuts, tree nuts, soy, wheat, fish, and shellfish, though other foods can also cause reactions. People with a personal or family history of allergies, asthma, or eczema may have a higher chance of developing food allergy. Cross-contact can happen when a safe food touches a trigger food during cooking, serving, or processing.
Who Is Affected
Food allergies can affect infants, children, teenagers, and adults. Some childhood food allergies may be outgrown, while others may continue for life. New food allergies can also begin in adulthood. People of any background or region can be affected.
Prevention
If you have a known food allergy, the main prevention step is strict avoidance of that food and careful label reading. Ask about ingredients when eating away from home, and watch for cross-contact in kitchens, schools, childcare settings, and social events. Families of infants should discuss food introduction questions with a qualified healthcare professional, because advice can vary depending on the child's history and risk. Do not try to test a suspected allergy at home.
Diagnosis and Tests
Diagnosis usually starts with a detailed history of what food was eaten, what symptoms happened, and how soon they started. A healthcare professional may use allergy-focused testing, such as skin or blood tests, along with the history. These tests alone do not always prove a food allergy, so interpretation by a qualified professional is important. In some cases, a supervised food challenge may be used in a medical setting.
Treatment Categories
Long-term management focuses on avoiding trigger foods and having an emergency action plan. A healthcare professional may prescribe emergency medicine for severe reactions and explain when and how it should be used. Mild reactions and severe reactions are managed differently, so clear instructions are important. Do not rely on home remedies for a suspected severe allergic reaction.
Living With It
Living with food allergy often means planning ahead for meals, travel, school, work, and celebrations. Many people find it helpful to tell family, friends, teachers, and coworkers about the allergy and what to do in an emergency. Wearing medical identification may also help in some situations. Emotional stress, fear of eating out, and social challenges are common and deserve support.
Diet and Lifestyle
Avoiding a food allergen can make it harder to meet nutrition needs, especially in children or when multiple foods must be avoided. A registered dietitian or other qualified nutrition professional can help with balanced meal planning and label-reading skills. Keep ingredient lists under review because products and recipes can change. Be cautious with buffets, shared utensils, and foods without clear labels.
When It May Be an Emergency
Emergency care is needed right away for trouble breathing, throat tightness, repeated vomiting after exposure, fainting, severe weakness, or widespread symptoms affecting more than one body system. Anaphylaxis can get worse fast and should be treated as a medical emergency. If severe symptoms happen after eating, use any prescribed emergency medicine as directed and seek emergency medical help immediately. If you are unsure whether a reaction is severe, get urgent medical help.