COMMENTARY

Food Allergy: What You Need to Know

Stephanie A. Leonard, MD

Disclosures

November 15, 2010

In This Article

Management of Food Allergy

Currently, no cure for food allergy exists. Management consists of education, prevention, and treatment of acute reactions. The mainstays of treatment of acute food-induced allergic reaction are antihistamines and intramuscular epinephrine.[10]

Treatment of Acute Reactions

Antihistamines can be given if symptoms develop or when a known allergen is ingested and symptoms have not yet developed. Evidence shows that oral cetirizine (0.25 mg/kg, maximum of 10 mg) works as fast as diphenhydramine (1.5 mg/kg, maximum of 50 mg); therefore, either can be used, and cetirizine has the added benefit of longer lasting effects.[61]

Epinephrine is used when respiratory or circulatory symptoms are present, or if the reaction is progressing and involves 2 or more organ systems. Epinephrine is appropriate, for example, if a patient has generalized hives and protracted vomiting, even without respiratory or circulatory symptoms.

Every patient diagnosed with a food allergy is advised to carry 2 epinephrine self-injectors because the severity of each reaction cannot be predicted, and in some cases, 2 doses might be needed. The dose of epinephrine is 0.01 mg/kg; using prepackaged epinephrine, adults receive 0.3 mg epinephrine per dose, and children under 25 kg (55 lbs) receive 0.15 mg epinephrine per dose.

Proper administration technique involves intramuscular injection of epinephrine into the thigh muscle. Studies have shown that injection of epinephrine into the thigh muscle achieves higher peak plasma concentrations than injection into the deltoid muscle, and absorption occurs faster with intramuscular vs subcutaneous administration.[62] Epinephrine can be injected through clothes if necessary; however, injecting directly against the skin avoids unseen buttons, seams, or zippers.

Patients are instructed to use their epinephrine when in doubt because a delay could allow the reaction to worsen. Patients are instructed to dial 911 or obtain immediate medical attention if the reaction is severe enough to use epinephrine. Not only might additional medication and monitoring be necessary, but the individual should be observed for 4-6 hours in the emergency department for a possible biphasic reaction.

Other components to emergency management include high-flow oxygen, inhaled beta-2 agonists for bronchospasm, and steroids.[10] Steroids (prednisone 1 mg/kg, maximum 50 mg; or methylprednisone 1-2 mg/kg) are not intended for acute management because their onset of action is slow; however, these agents could prevent biphasic or protracted reactions.[4] Dosing should be intravenous every 6 hours for severe reactions, whereas a single oral dose might suffice for milder reactions.[40]

In cases involving hypotension, H2-blockers (which not only improve cutaneous symptoms but also counteract vasodilation), fluid resuscitation, and a supine position could be useful.[10] Higher doses and intravenous administration of antihistamines can be given in a monitored setting. In refractory hypotension, vasopressors can be used. If a patient is taking beta-blockers, the effect of epinephrine could be diminished, and administration of glucagon might be necessary to reverse this blockade.

Avoidance of Exposure

Patients who have food allergies (and their caretakers) must be aware of the risks for hidden allergens or cross-contact at every meal, and frequently special provisions must be made for these individuals. Food allergies have a profound effect on quality of life,[63] and support groups and food allergy organizations (such as the Food Allergy and Anaphylaxis Network, or FAAN) might be useful. School, camp, restaurants, entertainment events, birthday parties, air travel, and vacationing can be stressful situations for food-allergic individuals. General nutritional health should be assessed periodically, and patients should be monitored for psychological issues such as anxiety and depression as well as food phobias and eating disorders.[64,65]

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