Food allergies

The symptoms of an allergic reaction to food include hives, lip/tongue/eye swelling, nausea, vomiting, diarrhea, abdominal pain, difficulty breathing, wheeze, cough, low blood pressure (dizziness, fainting), which occur within 30 minutes to 1 hour of eating a food. The most common food allergies are to: peanut, tree nuts, milk, egg, wheat, soy, sesame and seafood. In young children, milk, egg and peanut allergies are the most common. As we age these are quite rare to develop. In adults, shellfish allergy is more common to develop. Patients react to even small amounts of the food. The food has to be eaten or absorbed through moist membranes such as mouth, lips or eyes and it is not sufficient to be present in the room or be touching the food.

Once there is suspicion of food allergy the patient is evaluated by an allergist and testing may be done. Testing is not done as a panel and only foods that are of concern to have caused the reaction are tested. The testing available is very good if negative as it can rule out a food allergy, but a positive test has to be interpreted by the allergist in the context of the history of the reaction. Please see the section on diagnostic testing.

If a food allergy is suspected then the food is avoided and an epinephrine autoinjector is prescribed. Certain foods such as egg and milk have high rates of resolution of 70-80% by age 16. Other such as peanut are only 20% and tree nuts 10%. Fish and shellfish are even less likely to be outgrown. Depending on the food, history of reaction, testing results and age of patient, other options may be available to help outgrow the allergy or to help decrease the chance of a reaction to trace amounts of contaminant. For example, in egg or milk allergic patients, being able to eat baked egg or milk products regularly can help them outgrow the allergy faster.  In peanut allergic patients, eating small amount of peanut protein and increasing this slowly over time to 1 peanut daily is called oral immunotherapy and is used to decrease the chance of a severe reaction to very small amounts of peanut, however so far, this is not a cure and peanut has to be eaten daily or the risk of a reaction returns. This also does not mean that the patient can eat larger amounts of peanut. But, may provide flexibility in travel and decreased anxiety around eating at restaurants thus potentially improving quality of life. There is a risk of allergic reactions with this type of treatment and it is not offered by all allergists at this time. The best success has been shown in pre-school children. New treatments are under investigation at this time.

Patients always need to carry an epinephrine autoinjector and be ready to treat anaphylaxis. When a patient has eaten and develops symptoms of an allergic reaction, they need to alert others and monitor for anaphylaxis. If t here are 2 body systems involved: gastrointestinal (nausea, vomiting), skin (hives, swelling, flushing, itchiness), respiratory (wheeze, difficulty breathing, throat tightness, cough), or heart (low blood pressure symptoms such as dizziness, light-headed, losing consciousness) OR respiratory symptoms OR low blood pressure symptoms, then epinephrine should be administered using the EpiPen in the thigh muscle. Once epinephrine has been used for a reaction, the patient needs to present to an emergency room or call 911 as there is need for monitoring to ensure more epinephrine is not needed or other emergency treatments such as intravenous fluids or respiratory support. Antihistamines only treat itchiness and hives but will not prevent a severe allergic reaction from developing or progressing. Deaths from food allergy occur each year, typically from allergens that are already known to the patients. We advise caution and reading labels for products that “may contain” certain allergens.

In young children a yearly visit is recommended to monitor for the potential of outgrowing an allergy but also to review any accidental exposures, the anaphylaxis treatment plan and proper use of epinephrine. In older children or adults the visits may be less frequent but still important to review safety as well as any new treatment options.

Children with atopy (asthma, eczema, allergies) or a family history of atopy are at higher risk of food allergy. It is recommended to begin introducing allergenic foods at 6 months of age (given no delay in motor development that may impact feeding). This includes age appropriate forms of peanut, tree nuts (walnut, cashew, hazelnut, almond), egg, cow’s milk products and wheat. Once the food is introduced it should be kept in the diet and given regularly at least 3-4 times per week. If a food is not maintained in the diet there is a potential for an allergy to develop.

Dr. Ana-Maria Bosonea