Food Allergy and Anaphylaxis

ExitCare ImageA food allergy occurs when the body reacts to proteins found in food. In the most common type of food allergy, the immune system creates chemicals usually made to fight germs (antibodies). These chemicals cause problems when the protein is eaten. Problems can also happen when the food is touched or bits of food get into the air (such as while cooking) near someone who is allergic. The problems caused are the allergic symptoms.

This type of food allergy must be taken seriously. Even very small amounts of a food can cause a reaction. Severe reactions can be sudden and potentially fatal. This type of food allergy can vary from mild to life threatening (anaphylaxis). It is impossible to predict what the next reaction will be like based on previous reactions.

There can be other problems with food that are not actually allergies. This document only reviews food allergies.


It is not known why some people develop food allergy. It may be more common in families with other allergic problems. Any food can cause allergies but the most common ones are:

  • Peanuts.

  • Tree nuts (such as almonds, walnuts, hazelnuts, and pecans).

  • Fish (such as bass, flounder, and cod).

  • Shellfish (such as crab, lobster, and shrimp).

  • Milk.

  • Eggs.

  • Wheat.

  • Soybeans.


The symptoms of food allergy generally start within minutes to 2 hours after contact with the allergen. The symptoms can remain the same for several hours or get worse. Sometimes the reaction seems to improve only to return (often worse) later. Common signs/symptoms of a reaction include any or all of the following:

  • Skin: hives, itching, swelling, flushing.

  • Eyes: red, watery, itchy, swollen.

  • Nose: congested, runny, sneezing.

  • Mouth/throat: swelling of lips, tongue and throat. Itchy throat, hoarseness, choking sensation.

  • Lungs: Cough, difficulty breathing, wheezing (whistling noise when breathing out).

  • Gastrointestinal tract: Nausea (feeling sick to one's stomach), vomiting, diarrhea, cramps.

  • Heart and circulation: dizziness, weakness, fainting, turning pale, fast, slow or irregular pulse.

  • Nervous system: confusion, fear, sense of doom.

Anaphylaxis is the most serious food allergy reaction. It can rapidly cause throat and tongue swelling, difficulty breathing, low blood pressure, collapse and cardiac arrest (heart stops breathing).


The diagnosis of food allergy is made in part on the history of prior reactions. To prove the diagnosis and to find what foods are responsible, your caregiver may suggest:

  • Allergy skin tests – usually done by allergists in a setting where emergency treatment is available.

  • Blood tests for allergy.

  • Food challenges – suspected food is given and the person is observed in a setting where emergency treatment is available.

  • Food diary – recording foods eaten and reactions.

  • Elimination diet – suspected food(s) are removed from the diet.


Your caregiver may prescribe medicines to treat an allergic reaction such as:

  • Epinephrine (also called adrenaline), which comes in a self-injecting device. This is the most important medicine for treating serious food allergies.

  • Asthma medicine – usually inhaled – to treat breathing problems – in addition to epinephrine.

  • Antihistamines – to treat swelling and itching – in addition to epinephrine.

  • Steroids – given to calm down a serious reaction.

Children can outgrow certain food allergies (like milk and eggs). Peanut and tree nut allergies are less likely to be outgrown. Because of this, sometimes repeat allergy testing is done.


Avoid contact with the offending food. Strict avoidance is the only way to prevent a reaction.

  • Keep the food out of the house.

  • Learn how to read food labels in order to spot the presence of any food you are allergic to. If a packaged food product does not contain an ingredient label, avoid the food product.

  • If you must have the offending food in the house, discuss how to avoid it with your caregiver.

Be especially careful when eating in a restaurant.

  • Ask the cook or manager (not the waiter) if foods you are allergic to are found in any items on the menu.

  • Avoid:

  • Fried foods since oil can keep proteins from previously cooked foods.

  • Ice cream parlors, Asian restaurants and bakeries - these often use peanut or tree nut ingredients.

  • Buffets, picnics, school lunches and salad bars because of the risk of contact with foods you are allergic to.

  • Food prepared in a blender or shared grill.

  • Request that food be prepared with clean utensils or pans to avoid contamination from prior foods.

  • Let the staff know you have allergies that can cause serious reactions or death.

  • If you have a reaction, administer treatment and tell the staff to immediately call for emergency services ( 911 in the U.S.).

If planning travel by air, inform the airline ahead of time (when making the reservation) that you have a food allergy.

Wear a medical identification bracelet or necklace (such as one offered by MedicAlert ®) noting your allergy.

If an epinephrine self-injector device is prescribed:

  • Carry your device everywhere at all times.

  • Learn how to use the device. Practice by injecting an expired injector into an orange.

  • Teach all family members, teachers, coaches, etc to use the injector.

  • Make an injector available at school, work, etc.

  • Keep a spare injector in your car.

  • Educate others about your allergy. This includes school teachers and other school personnel. Tell them what you need to avoid, the symptoms of an allergic reaction, and how others can help during an allergic emergency.

  • If you experience a subsequent allergic reaction, administer epinephrine promptly and immediately call for emergency services (911 in the U.S.).


  • You have questions about food allergy or its treatments.

  • Allergy reactions are getting worse or more frequent.

  • You suspect new food allergies.


  • You or your child has a serious allergic reaction, even if you have given a shot of epinephrine.

  • Symptoms return after taking prescribed treatments.


  • Understand these instructions.

  • Will watch your condition.

  • Will get help right away if you are not doing well or get worse.