Food Allergy in Children

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Author: V. Dimov, M.D.

Let's look at the terms used to describe adverse reactions to food:

- adverse food reaction - any untoward reaction to food or food additive
- food allergy (FA) - reaction that has immunologic mechanism (IgE-mediated or non-IgE-mediated)
- food intolerance or sensitivity - reaction that has nonimmunologic mechanism
- oral allergy syndrome (OAS) - "urticaria of the mouth" - local reaction to raw fruits and vegetables due to cross-reactivity between aeroallergen (pollen) and food allergen

However, a patient may have both intolerance AND allergy to the same food - e.g. milk - lactose intolerance AND milk allergy.

Any food can cause food allergy in theory but there are 8 most common food allergens. More than 90% of food allergies are due to:

- egg, milk, peanuts, tree nuts - the 4 most common food allergens in children
- soy, wheat, fish, and shellfish - these 4 tend to start later in life, in adults

Symptoms of food allergy

- cutaneous - hives occur in 80% of significant food allergic reactions
- gastrointestinal (GI) - cramping, diarrhea, vomiting
- respiratory
- cardiovascular - low blood pressure
- strangely and rarely, some children may exhibit only central nervous system symptoms, e.g. somnolence
- anaphylaxis - systemic allergic reaction that involves multiple organ systems

Anaphylaxis

Anaphylaxis is the most dangerous manifestation of food allergy ("nuclear bomb") and typically has a rapid onset. This is an "Epi moment" - an event that must be recognized and addressed promptly.

Clinical manifestations of anaphylaxis may vary from mild to fatal:

- cutaneous - hives and/or angiodema
- respiratory - wheezing
- GI symptoms

Anaphylaxis can be biphasic - initial symptoms, then followed 6-8 hr later by second phase.

The best treatment of anaphylaxis is immediate administration of epinephrine auto-injector. The auto-injector (e.g., EpiPen, Twinject) must be available at all times. This is an "Epi moment". After administration of epinephrine, call 911 for transport to ED. If no response to epinephrine within 5 to 10 min, repeat the dose.

Remember the simple rule: "No Epi, no eat-y".

Twitter comments:

@lissaRFAK: I think I found my new personal slogan. Let's make t-shirts. RT @Allergy One allergist used to say: "No Epi, no eat-y" (always be prepared).

Some small studies suggest the use of activated charcoal to bind the ingested food allergen in the stomach. However, this cannot be recommended for children due to potential for aspiration.

Diagnosis of food allergy

Skin prick testing is helpful when negative becuase it has a high negative predictive value. Skin prick testing can be problematic when positive because of false-positive reactions. Do not use intradermal skin tests - they are dangerous and have a high false-positive rate.

Treatment of food allergy

When to give epinephrine?

In any food allergy reaction that extends beyond the skin, or if the child becomes unstable, confused, somnolent, etc. Simple rule: "If it is more than the skin, the Epi goes in."

Do not give antihistamine in place of epinephrine.

Auto-injectable epinephrine devices

Administered between knee and hip. Some studies suggest that 15-35% of patients with an anaphylactic episode required a second dose of epinephrine.

- EpiPen auto-injector available in “2-Pak” - 2 injectors.

- Twinject contains 2 doses in one device - the second dose is “hidden” inside device. However, the second dose must be administered by another individual/parent with a needle and plunger.

What happens after using an EpiPen?

This is an "Epi moment". After using the epinephrine auto-injector, the symptoms should resolve within 1 to 2 minutes. If they do not, give a second dose.

Children and parents should be encouraged to use expired device to practice auto-injection technique on grapefruit or orange fruit.

The use of medical identification alert jewelry is recommended, e.g. MedicAlert bracelet.

Similarly, to asthma action plan, a food allergy action plan (FAAP) should be available to patients. One version is provided by the website of the Food Allergy & Anaphylaxis Network (FAAN).

Oral immunotherapy for food allergy

Patients with peanut allergy can be desensitized by giving peanut in small incrementally increasing doses until a maintenance dose reached. There is a high rate of reactions to this therapy and the results are still not conclusive. The studies of oral immunotherapy for food allergy are ongoing.

References

Practical Management of Food Allergies. Michael J. Welch, MD. Audio-Digest Pediatrics, Volume 56, Issue 01, January 7, 2010.

Published: 06/02/2010
Updated: 03/02/2011