What is a food allergy?
When you have a food allergy, your body thinks certain foods are trying to harm you. Your body fights back by setting off an allergic reaction. In most cases, the symptoms are mild—a rash or an upset stomach. A mild reaction is no fun, but it isn't dangerous. A serious reaction can be deadly. But quick treatment can stop a dangerous reaction.
Food allergies are more common in children than in adults. Children sometimes outgrow their food allergies, especially allergies to milk, eggs, or soy. But if you develop a food allergy as an adult, you will most likely have it for life.
Many people think they have a food allergy, but in fact they have food intolerance. An intolerance can cause some of the same symptoms as a mild food allergy, like an upset stomach. It can make you feel bad, but it isn't dangerous.
Food intolerances are much more common than food allergies. True food allergies are a reaction to food or food additives by your body's immune system. But a food intolerance doesn't cause an allergic reaction.
What causes it?
Food allergies occur when your body's immune system overreacts to substances in food you have eaten. This triggers an allergic reaction. Food allergies are more common in young children than in adults.
- Milk, eggs, peanuts, tree nuts, fish, shellfish, wheat, and soy cause most problems in children. Some babies are so sensitive to these foods that if the food is eaten by the mother, drinking her breast milk can cause a reaction. Most children outgrow allergies to eggs, milk, wheat, and soy.
- Peanuts, tree nuts, fish, and shellfish cause most of the allergic reactions in teens and adults. Adults typically remain allergic to the food for life.
If you are highly sensitive to a certain food, you may have an allergic reaction just by being near where the food was prepared or served.
What are the symptoms?
Food allergies can cause many different symptoms. They can range from mild to serious. A mild reaction may include tingly lips, a stuffy nose, dizziness, and a few raised, red, itchy patches of skin (called hives).
The most severe reaction is called anaphylaxis (say "ANN-uh-fuh-LAK-suss"). It affects your whole body. Anaphylaxis can start within a few minutes to a few hours after you eat the food. The symptoms can go away and come back hours later. A severe reaction may cause hives all over, swelling in the throat, trouble breathing, nausea or vomiting, or fainting.
How is it diagnosed?
Your doctor will ask questions about your past health and family food allergies. And he or she will do a physical exam. Your doctor will also ask what symptoms you have when you eat certain foods.
Because food allergies can be confused with other problems, your doctor may do some tests. You may have either skin testing or a blood test. These tests help to see what you are allergic to. An oral food challenge is another way to diagnose a food allergy. You will eat a variety of foods that may or may not cause an allergic reaction. Your doctor watches to see if and when a reaction occurs.
How are allergic reactions to food treated?
The best treatment for allergic reactions to food is to avoid the food that causes the allergy. When that isn't possible, you can use medicines such as antihistamines for mild reactions and epinephrine for serious reactions. Epinephrine is a shot that you can give yourself when needed.