Food Allergy

A food allergy is an immune system reaction to a food. A food allergen is an ingredient or chemical in a food that causes your immune system to react. Allergic reactions happen when your immune system fights too strongly against an allergen and causes you to get sick. Allergic reactions can happen within minutes to several hours after you eat, touch, or smell the food. You can also have a second reaction up to 8 hours later.

What increases my risk for a food allergy?

A food allergy can develop at any time. Many children outgrow their allergies to milk, wheat, and egg by late childhood. Food allergies that develop in adults often do not go away. Food allergies often begin in children aged 2 years or younger, more commonly in boys. The risk is also greater if a close family member has a food allergy. You are more likely to have food allergies if you also have eczema, hay fever, or asthma.

What are the most common food allergies?

• Nuts
• Eggs
• Fish and shellfish
• Fruits and vegetables
• Milk
• Soy
• Wheat

How are food allergies diagnosed?

Your healthcare provider will ask about your symptoms after you eat, touch, or smell certain foods. He will ask how long it takes for symptoms to appear and how long they last. He will also ask about the amount of food that triggers symptoms. You may need to keep a food diary to write down everything you eat and any symptoms that develop. You may need additional testing if you developed anaphylaxis after you were exposed to a trigger and then exercised. This is called exercise-induced anaphylaxis. A trigger can be any food or a specific food you are allergic to. You may also need the following:

A skin prick test is used to check for an allergy to certain foods. Your healthcare provider will scratch tiny bits of different foods under your skin. If a bump appears within a few minutes, you likely have an allergy to that food.

• Blood tests may be used to find antibodies that lead to food allergies. An antibody is part of your immune system.
• An elimination diet is used to help you avoid a food for several weeks to see if your symptoms get better.
• Food challenge means you eat small amounts of foods that you may be allergic to. A healthcare provider stays with you to watch for and treat any allergic reactions.

What are the signs and symptoms of a food allergy?

• Mild symptoms include itching, a rash, or swelling.
• Anaphylaxis symptoms include throat tightness, trouble breathing, tingling, dizziness, and wheezing. Anaphylaxis is a sudden, life-threatening reaction that needs immediate treatment.

How is an allergic reaction to food treated?

• Antihistamines decrease mild symptoms such as itching or a rash.
• Epinephrine is used to treat severe allergic reactions such as anaphylaxis.

What steps do I need to take for signs or symptoms of anaphylaxis?

• Immediately give 1 shot of epinephrine only into the outer thigh muscle.
• Leave the shot in place as directed. Your healthcare provider may recommend you leave it in place for up to 10 seconds before you remove it. This helps make sure all of the epinephrine is delivered.
• Call 911 and go to the emergency department, even if the shot improved symptoms. Do not drive yourself. Bring the used epinephrine shot with you.

What safety precautions do I need to take if I am at risk for anaphylaxis?

• Keep 2 shots of epinephrine with you at all times. You may need a second shot, because epinephrine only works for about 20 minutes and symptoms may return. Your healthcare provider can show you and family members how to give the shot. Check the expiration date every month and replace it before it expires.
• Create an action plan. Your healthcare provider can help you create a written plan that explains the allergy and an emergency plan to treat a reaction. The plan explains when to give a second epinephrine shot if symptoms return or do not improve after the first. Give copies of the action plan and emergency instructions to family members, work and school staff, and daycare providers. Show them how to give a shot of epinephrine. Update the plan as the allergy changes.
• Be careful when you exercise. If you have had exercise-induced anaphylaxis, do not exercise right after you eat. Stop exercising right away if you start to develop any signs or symptoms of anaphylaxis. You may first feel tired, warm, or have itchy skin. Hives, swelling, and severe breathing problems may develop if you continue to exercise.
• Carry medical alert identification. Wear jewelry or carry a card that says you have a food allergy. Ask your healthcare provider where to get these items.
• Do not eat the food that causes your allergy. Even a small taste can cause an allergic reaction. Your healthcare provider or a dietitian can help you plan a balanced diet. Babies may need to drink a formula that does not contain milk or soy. A dietitian can teach you how to read labels for ingredients that cause your allergies.
• Ask about ingredients in foods prepared outside your home. When you eat out, ask what is in the food you want to order. Ask how food is prepared. Fried foods may contain small amounts of food allergens, such as nuts and shellfish.
• Use good hygiene. Do not share utensils or food. Wash your hands before and after meals.

When do I need to follow up with a healthcare provider?

You may need to see specialists, such as an allergist or dietitian, for ongoing care. Your healthcare provider may want to test you regularly to see if the food allergy changes. Write down your questions so you remember to ask them during follow-up visits.

Is the flu vaccine safe for an egg allergy?

Do not get the nasal spray form of the flu vaccine if you have an egg allergy. The nasal spray may contain egg proteins that can cause anaphylaxis. Ask your healthcare provider if the injection form of the vaccine is safe for you.

Call 911 for signs or symptoms of anaphylaxis,

such as trouble breathing, swelling in your mouth or throat, or wheezing. You may also have itching, a rash, hives, or feel like you are going to faint.

When should I seek immediate care?

• You have itching or hives that spread all over your body.

When should I contact my healthcare provider?

• You have new or worsening rashes, hives, or itching.
• You have an upset stomach or are vomiting.
• You have stomach cramps or diarrhea.
• You have questions or concerns about your condition or care.