Food allergy is an immune system reaction that occurs soon after eating a certain food. Even a tiny amount of the allergy-causing food can trigger signs and symptoms such as digestive problems, hives or swollen airways. In some people, a food allergy can cause severe symptoms or even a life-threatening reaction known as anaphylaxis.
Food allergy affects an estimated 6 to 8 percent of children under age 5, and about 3 to 4 percent of adults. While there's no cure, some children outgrow their food allergy as they get older. It's easy to confuse a food allergy with a much more common reaction known as food intolerance. While bothersome, food intolerance is a less serious condition that does not involve the immune system.
For some people, an allergic reaction to a particular food may be uncomfortable but not severe. For other people, an allergic food reaction can be frightening and even life-threatening. Food allergy symptoms usually develop within a few minutes to two hours after eating the offending food. Food allergies can occur even the first time you eat a food.
The most common food allergy symptoms include:
Emergency treatment is critical for anaphylaxis. Untreated, anaphylaxis can cause a coma or death.
Exercise-induced food allergy
Pollen-food allergy syndrome
Common cross-reactivity between pollens and fruits and vegetables:
When to see a doctor
Seek emergency treatment if you develop any signs or symptoms of anaphylaxis, such as:
When you have a food allergy, your immune system mistakenly identifies a specific food or a substance in food as something harmful. Your immune system triggers cells to release antibodies known as immunoglobulin E (IgE) antibodies to neutralize the culprit food or food substance (the allergen). The next time you eat even the smallest amount of that food, the IgE antibodies sense it and signal your immune system to release a chemical called histamine, as well as other chemicals, into your bloodstream.
These chemicals cause a range of allergy signs and symptoms. They are responsible for causing allergic responses that include dripping nose, itchy eyes, dry throat, rashes and hives, nausea, diarrhea, labored breathing, and even anaphylactic shock.
The majority of food allergies are triggered by certain proteins in:
In children, food allergies are commonly triggered by proteins in:
Chocolate, long thought by some parents to cause food allergies in children, rarely triggers a food allergy.
Food intolerance and other reactions
One of the tricky aspects of diagnosing food intolerance is that some people are sensitive not to the food itself but to a substance or ingredient used in the preparation of the food.
Common conditions that can cause symptoms mistaken for a food allergy include:
Food allergy risk factors include:
Factors that may increase your risk of developing an anaphylactic reaction include:
Complications of food allergy can include:
While some people think food allergies are linked to childhood hyperactivity and to arthritis, there's no evidence to support this.
Preparing for your appointment
Because doctor's appointments can be brief, and because there's often a lot of ground to cover, it's a good idea to be well prepared for your appointment. Here's some information to help you get ready for your appointment, and what to expect from your doctor.
Your time with your doctor is limited, so preparing a list of questions will help you make the most of your time together. List your questions from most important to least important in case time runs out. Some basic questions to ask your doctor include:
If your child is seeing the doctor for a food allergy, you may also want to ask:
In addition to the questions that you've prepared to ask your doctor, don't hesitate to ask questions during your appointment at any time that you don't understand something.
What to expect from your doctor
What you can do in the meantime
Tests and diagnosis
There's no standard test used to confirm or rule out a food allergy. Your doctor will consider a number of things before making a diagnosis. The following may help determine if you're allergic to a food or if your symptoms are caused by something else:
Treatments and drugs
The only way to avoid an allergic reaction is to avoid the foods that cause signs and symptoms. However, despite your best efforts, you may come into contact with a food that causes a reaction.
For a minor allergic reaction, over-the-counter or prescribed antihistamines may help reduce symptoms. These drugs can be taken after exposure to an allergy-causing food to help relieve itching or hives. However, antihistamines can't treat a severe allergic reaction.
For a severe allergic reaction, you may need an emergency injection of epinephrine and a trip to the emergency room. Many people with allergies carry an epinephrine autoinjector (EpiPen, EpiPen Jr, Twinject). This device is a combined syringe and concealed needle that injects a single dose of medication when pressed against your thigh. If your doctor has prescribed an epinephrine autoinjector:
Lifestyle and home remedies
One of the keys to preventing an allergic reaction is to completely avoid the food that causes your symptoms.
Research on alternative food allergy treatments is limited. However, many people do try them and claim that certain treatments help.
Coping and support
A food allergy can be challenging and a source of ongoing concern. Having a good source of information and the opportunity to discuss the condition with others who share your concerns can be very helpful. A number of Internet sites and nonprofit organizations offer information and forums for discussing food allergies. Some are specifically for parents of children with food allergies. The Food Allergy and Anaphylaxis website can direct you to support groups and events in your area. Many people find it helpful to talk to others who are dealing with the same challenges.
The best way to prevent an allergic reaction is to know and avoid foods that cause signs and symptoms. For some people, this is a mere inconvenience, but others find it a greater hardship. Also some foods — when used as ingredients in certain dishes — may be well hidden. This is especially true in restaurants and in other social settings.
If you know you have a food allergy, follow these steps:
If your child has a food allergy, take these precautions to ensure his or her safety:
Last Updated: 2011-02-11
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