Food allergies are common, affecting about 6 percent of children and 2 percent of adults. However, they are often misunderstood. St. John’s board-certified allergist Greg Lux, M.D., answers your questions about children and food allergies.

Q. What foods most commonly cause allergies?

Although you can be allergic to almost any food, most food allergies are caused by milk, eggs, peanuts, tree nuts, wheat, soy, fish and shellfish.
It is important to distinguish a food allergy from a food intolerance. An allergy is an immunologic reaction due to the production of IgE antibodies, which cause the release of histamines, causing hives, asthma, itching in the mouth, trouble breathing, stomach pains, vomiting, and/or diarrhea. Gluten sensitivity, for instance, is not IgE mediated and is not a true allergy.
The difference is important because a true allergy to a food can lead to a fatal reaction within minutes. That is why those with a food allergy must carry epinephrine to treat a reaction, because epinephrine works within a few minutes to stop an allergic reaction from becoming fatal. People diagnosed with a food allergy need to avoid any exposure to the food because they could have a fatal reaction before help can arrive.
Most people experience adverse food reactions and intolerances sometime during their life. They may get headaches from tyramine in aged, yellow cheese. They may get sick from certain spices or cramps from a variety of foods. These reactions are significant and the food should be avoided, but accidental ingestion is not likely to cause a fatal reaction within a few minutes.

Q. At what age can allergy tests be performed, and how are they performed?

We can skin-test newborns and any age thereafter, as long as the skin is healthy. Food-allergy diagnosis is best made by skin testing. There are a variety of blood tests, but they have no better accuracy than the skin tests done by an allergist. It is important to test only for the foods that are suspected because there is a good chance that “false positive” results will be found where a food is reported as positive and yet causes no reaction when eaten. The testing is merely confirmatory of your history. In other words, a food allergy cannot be predicted. You must have a reaction to know that it exists. Because a food allergy is such a serious diagnosis, most physicians suggest that it be made by a board-certified allergist.

Q. Can food allergies be prevented?

Food allergy can appear at any age and requires previous exposure.  It is not a “new” food that you become allergic to, but often a food that you have eaten on previous occasions without a reaction. You can become allergic as an adult to a food that you have enjoyed for 50 years.
Exclusive breastfeeding is encouraged as long as the mother can commit to it. Because children have an immature gut wall and are learning to digest foods just as parents are learning what foods the child enjoys, most experts suggest that “allergy-prone” foods be introduced later. Peanuts and eggs are common allergens and should not be introduced for one to two years. Seafood should be withheld until several years of age.
There is no reason to remove similar foods from the diet as people with shrimp allergy can often eat lobster without harm and those with walnut allergy can eat almonds without harm, or vice versa.

Q. What are the symptoms of a food allergy?

The symptoms of true food allergy are usually hives. Hives occur in almost 60 percent of reactions. The next most common symptom is breathing problems, even without a history of asthma. It’s important to know that anaphylaxis may occur where the patient passes out from a loss of blood pressure and dies without any hives or breathing symptoms preceding the death.

Q. How are reactions treated?

Epinephrine is usually prescribed as an Epi-Pen. This automatic injector comes in two doses, 0.15 mg for 33 pounds of body weight and 0.30 mg for 66 pounds. Babies require the measurement of smaller doses and a manual injection. Most experts recommend two Epi-Pens be available because the device is not used correctly in up to a third of emergency situations and the second is needed as a “back-up” device.

Benadryl is an important medication as well. Chewable tablets work as fast as liquid formulations without the hassle of breaking or spilling. Benadryl should be administered as soon as a reaction is suspected. It can often treat milder reactions if given quickly.

Treatment should be started by the patient or adult attendant for a child as soon as a reaction is recognized. The speed with which medication is administered is directly related to the likelihood of recovery. It is important for someone with a food allergy to tell everyone they know that they have a food allergy as you might not be able to treat yourself.

Research is on-going about allergy shots in the treatment of food allergies, but the results are not conclusive. At the present time we are limited to identifying the food, avoiding the food, and being prepared to treat a reaction when it occurs.

Q. Are food allergies more common nowadays?

All allergies have been increasing for the past two decades.

Food allergy is more common in childhood, so there is a chance that a child can “outgrow” an allergy. But the more severe the allergy, the more likely it will remain a lifelong problem.

Q. What are some good resources for parents of children with food allergies?

A. The best source for food allergy information is the Food Allergy Network, www.foodallergy.org.
Their information is limited to the diagnosis and treatment of true food allergy. Other sources must be researched for other types of immune reactions or adverse reactions to food.