Tip of the Day Cough with exercise can be a sign of asthma.
How common are food allergies?
It is estimated that 12 million Americans have food allergies.
Food allergies are more common in children than in adults.
Food allergy is the leading cause of severe allergic reactions (anaphylaxis) outside of the hospital.
Are all food allergies potentially dangerous?
No. The majority of individuals with food allergies have symptoms that are not considered life threatening.
These symptoms may include: hives and itching of the skin, diarrhea, eczema, abdominal cramping and less commonly, nasal congestion and coughing.
How do I know if I have food allergies?
A wide variety of symptoms can sometimes be blamed on food allergies.
A true food allergy is caused by the release of allergic mediators such as histamine that result in the symptoms. If you have a food allergy, your immune system overreacts to the protein part of the food by producing specific allergic antibodies (IgE) that in turn recognize the food protein and react to it.
Many patients who think they have a food allergy actually have a food intolerance. Most people have a list of foods that may cause unwanted symptoms such as excess gas and cramping that are not due to an allergic sensitivity but rather to some difficulty in digesting or processing the food in the gut. Common foods intolerances include onions, bell peppers, broccoli.
The best way to determine if you may have a food allergy is to restrict a suspicious food from your diet for a period of several weeks and see if the symptoms improve. If reintroduction of the food triggers the same symptoms once again, there is a good chance you have a food allergy.
When is a food allergy dangerous?
A small number of patients develop more serious allergic reactions to foods. This is called anaphylaxis and it is a potentially life threatening emergency.
Symptoms of anaphylaxis include: widespread hives, swelling of the lips and throat, wheezing, drop in blood pressure and sometimes loss of consciousness.
These symptoms usually develop within minutes of eating the food. In rare cases, the reaction may be delayed for several hours.
Without immediate treatment, the outcome can be fatal.
It is therefore very important to identify the food trigger and be prepared to treat symptoms immediately.
How are food allergies diagnosed?
If you have had a more serious reaction to a food, it is very important to see the allergist for further testing to help identify the food trigger.
The most common food groups causing life-threatening reactions are shellfish, peanuts, tree nuts, and eggs.
In some food groups, especially tree nuts and seafood, an allergy to one member of a food family can potentially result in the individual being allergic to the other members of the family. For exxample, it is not uncommon for patients who have had a reaction to almonds to also be sensitive to cashews.
Skin testing can be performed to a variety of foods. A small amount of an extract made from a food is placed on the skin. If a small hive develops within 20 mins, you may have an allergy to that food.
RAST tests (a blood test) provide a more quantifiable measure of food sensitivity by looking at how much allergic antibody (specific IgE to a particular food) is circulating in the blood. In many cases, it is important to perform both types of tests before making treatment recommendations.
Food challenges are sometimes done in an office setting to prove that a given food is causing the described symptoms. The patient is monitored for certain signs and symptoms after ingesting increasing amounts of a given food over 1-2 hours.
How are food allergies treated?
Once the food triggers are identified, the best way to treat the allergic symptoms is avoidance of the food (and possible other members of that food family).
It is important to read labels and check for the presence of the offending food in restaurant dishes.
If you have had a serious, life-threatening reaction to a food, it is mandatory to develop a treatment plan with the allergist. An Epi-pen (self-injectable epinephrine) and Benadryl should be with you at all times in case of accidental ingestion.
Teachers and day care providers should be educated about your child's food allergies and know how to administer the necessary treatment.
Can I outgrow food allergies?
The majority of children will eventually outgrow cow's milk, egg, soy and wheat allergy even if they have had a more severe reaction to the food.
On the other hand, only about 20% of children will lose a peanut sensitivity and 9% a tree nut sensitivity.
If you have had a history of a more severe allergic reaction to a food, never challenge yourself with that food without first consulting with the allergist to determine if the sensitivity has indeed been lost.