Food Allergies

What is Food Allergies?

Food allergies happen when your immune system mistakenly identifies certain foods as dangerous invaders. Your body then produces antibodies called Immunoglobulin E, or IgE, to fight off these foods. When you eat that food again, these IgE antibodies trigger the release of chemicals like histamine that cause allergic symptoms.

Food allergies are different from food intolerances or sensitivities. A true food allergy involves your immune system and can cause serious, even life-threatening reactions. Food intolerance usually involves your digestive system and tends to cause milder symptoms. About 32 million Americans have food allergies, including 1 in 13 children.

The most common food allergens are milk, eggs, peanuts, tree nuts, soy, wheat, fish, and shellfish. These eight foods account for about 90 percent of all allergic reactions. Food allergies can develop at any age, though many children outgrow allergies to milk, eggs, wheat, and soy by their teenage years.

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Symptoms

Hives, itching, or eczema on the skin
Swelling of the lips, face, tongue, or throat
Wheezing, trouble breathing, or nasal congestion
Stomach pain, nausea, vomiting, or diarrhea
Dizziness, lightheadedness, or fainting
Tingling or itching in the mouth
Anaphylaxis, a severe whole-body reaction that can be fatal

Symptoms typically appear within minutes to 2 hours after eating the trigger food. Some people experience mild reactions at first that become more severe with repeated exposure. Anaphylaxis is a medical emergency that requires immediate treatment with epinephrine.

Causes and risk factors

Food allergies develop when your immune system becomes sensitized to specific proteins in certain foods. The exact reason why some people develop food allergies while others do not is still being studied. Genetics play a significant role, as food allergies tend to run in families. If one or both parents have allergies, asthma, or eczema, children are more likely to develop food allergies.

Other risk factors include having other allergic conditions like asthma or eczema, being a young child, and having certain gut health issues. Some research suggests that delayed introduction of common allergens to babies may increase allergy risk. Environmental factors and how your gut bacteria develop in early life may also influence whether you develop food allergies. Once sensitized, your immune system overreacts every time you eat that particular food.

How it's diagnosed

Food allergies are typically diagnosed through a combination of medical history, physical examination, and specialized testing. Your doctor will ask detailed questions about your symptoms, what foods you ate, and how quickly symptoms appeared. Keeping a food diary can help identify patterns and potential trigger foods.

Blood tests that measure Immunoglobulin E antibodies to specific foods can help identify allergies. These tests show whether your immune system has created antibodies against particular food proteins. Skin prick tests are also commonly used, where small amounts of food proteins are placed on your skin to see if a reaction occurs. In some cases, your doctor may recommend an oral food challenge, where you eat small amounts of the suspected food under medical supervision. Talk to your doctor about which testing approach is right for your situation.

Treatment options

Strict avoidance of the trigger food by reading labels carefully
Carrying epinephrine auto-injectors if you have a history of severe reactions
Antihistamines for mild allergic symptoms like hives or itching
Working with a registered dietitian to ensure proper nutrition while avoiding allergens
Educating family, friends, and caregivers about your food allergies
Wearing medical alert jewelry that identifies your specific food allergies
Creating an emergency action plan with your doctor
Considering oral immunotherapy under medical supervision for certain allergies

Frequently asked questions

A food allergy involves your immune system creating IgE antibodies against specific food proteins, which can trigger serious or life-threatening reactions. Food intolerance usually involves your digestive system and causes milder symptoms like bloating or stomach discomfort. Allergies typically cause symptoms within minutes to 2 hours, while intolerances may take longer to appear.

Yes, food allergies can develop at any age, even if you have eaten that food without problems for years. Adult-onset food allergies are becoming more common, particularly allergies to shellfish, tree nuts, fish, and peanuts. The reasons why some adults suddenly develop allergies are not fully understood but may involve changes in the immune system or gut health.

Anaphylaxis is a severe, whole-body allergic reaction that can be life-threatening. Signs include difficulty breathing, swelling of the throat or tongue, rapid pulse, dizziness, severe drop in blood pressure, and loss of consciousness. Anaphylaxis requires immediate treatment with epinephrine and emergency medical care. Anyone at risk should carry two epinephrine auto-injectors at all times.

Blood tests that measure IgE antibodies to specific foods can be helpful but are not perfect on their own. They show whether you have antibodies to a food, but positive results do not always mean you will have an allergic reaction when eating it. Your doctor will interpret blood test results along with your medical history and symptoms to make an accurate diagnosis.

Many children outgrow allergies to milk, eggs, wheat, and soy, often by their teenage years. About 80 percent of children with milk or egg allergies will outgrow them by age 16. However, allergies to peanuts, tree nuts, fish, and shellfish are more likely to be lifelong. Your allergist can perform periodic testing to determine if your child has outgrown their allergy.

Eight foods cause about 90 percent of all allergic reactions. These are milk, eggs, peanuts, tree nuts, soy, wheat, fish, and shellfish. Sesame was recently added as the ninth major allergen in the United States. These foods must be clearly labeled on packaged foods to help people with allergies avoid them.

Recent research suggests that introducing common allergens like peanuts and eggs to babies between 4 and 6 months of age may actually reduce allergy risk. This is a change from older advice to delay these foods. Talk to your pediatrician about the best timing for your baby, especially if there is a family history of allergies or if your baby has eczema.

If you have a history of severe reactions, use your epinephrine auto-injector immediately and call 911, even if symptoms seem mild at first. For mild reactions, take an antihistamine and monitor your symptoms closely. Never assume a reaction will stay mild, as symptoms can worsen quickly. Always seek medical attention after using epinephrine.

Major allergens must be clearly listed on food labels in the United States. Check both the ingredient list and the allergen statement, which usually says contains milk, eggs, or other allergens. Be aware that allergens can hide in unexpected places like medications, cosmetics, and non-food items. When in doubt, contact the manufacturer or avoid the product.

Oral immunotherapy involves eating tiny, gradually increasing amounts of an allergen under medical supervision to build tolerance. This treatment is available for some allergies, particularly peanut allergy, and must only be done with a trained allergist. It does not cure the allergy but may reduce the severity of accidental exposures. The treatment requires months to years of careful monitoring.