24.5 Allergy to Food

Learning Objectives

By the end of this section, you will be able to:

• Discuss the pathophysiology, risk factors and clinical manifestations for food allergies
• Describe the diagnostics and laboratory values for patients experiencing food allergies
• Apply nursing concepts and plan associated nursing care for patients with food allergies
• Evaluate the efficacy of nursing care for patients with food allergies
• Describe the medical therapies that apply to the care of patients with food allergies

Food allergies are IgE-mediated type I hypersensitivity reactions. Over 170 foods have been reported to cause allergic reactions. The most common foods known to cause food allergies are peanuts, tree nuts, seafood (lobster, crab, shrimp, clams, fish), chocolate, berries, eggs, wheat, and milk. The most severe reactions are caused by peanuts and tree nuts. Because foods may be hidden within a recipe and not obvious to those with a food allergy, the basic act of eating can pose a huge risk of escalating to anaphylaxis. For this reason, equipment used to prepare food with a particular allergen is considered contaminated and should not be used by people with an allergy to that allergen. For example, a bakery that makes desserts with peanuts in a particular mixer should use a completely different mixer to make desserts that do not contain peanuts.

Pathophysiology

Once exposed, the allergen facilitates the production of allergen-specific IgE antibodies by plasma cells. The allergen-specific IgE binds itself to the surface of mast cells and basophils. This is the process known as sensitization, when antibodies are formed. Upon re-exposure to the allergen, the allergen cross-links IgE molecules on the surface of the mast cell or basophil membrane. The mast cells and basophils then release several chemical mediators initiating the inflammatory phase, which may include pruritus and smooth muscle contraction of the respiratory tract, gastrointestinal tract, and blood vessels. Leukotrienes and prostaglandins are also released. Leukotrienes can cause smooth muscle contraction, bronchial constriction, mucus airway secretions, and wheal-and-flare skin reactions. Prostaglandins produce smooth muscle contraction, increased capillary permeability, and vasodilation. This chemical mediator sensitizes pain receptors and increases pain from inflammation. Prostaglandins also elicit inflammation and boost the effects of mediators in inflammatory responses.

Link to Learning

The Institute of Agriculture and Natural Resources at the University of Nebraska–Lincoln maintains a Food Allergy webpage with information about many kinds of food allergies. There is also a video explaining how food allergies develop.

Clinical Manifestations

Clinical manifestations of food allergies range from mild to life threatening. Reactions can occur within minutes to hours after exposure. A wide range of allergy and gastrointestinal symptoms may include urticaria, wheezing, cough, angioedema, laryngeal edema, dermatitis, diarrhea, nausea, vomiting, abdominal pain, itching, swelling (lips, tongue, palate), and cramps. Anaphylaxis may also occur with food allergies.

Assessment and Diagnostics

A thorough allergy history, physical examination, and diagnostic tests are needed for a food allergy workup. Skin testing may also be done to aid in a diagnosis. The patient may also be advised to maintain a food diary that list foods consumed and any symptoms that follow, and even to eliminate certain foods from their diet in order to monitor the effects.

Diagnostics and Laboratory Values

Skin testing may be performed to assist in identifying food allergens, though false-positive or false-negative results are possible. Serum IgE levels may also be assessed. Elevated results indicate the IgE-mediated response, confirming the allergy. If a food cannot be identified as the cause, some providers may recommend the patient follow a nonallergenic food diet, which eliminates known food allergens.

Nursing Care of Patients with a Food Allergy

Nurses play an important role in managing care for those with food allergies. Nursing care includes conducting an assessment to recognize and analyze cues, prioritizing hypotheses, generating solutions, taking action, and evaluating care and outcomes. If any outcomes have been deemed nonsatisfactory, such as patient continues to complain of itchiness, then the nurse must start over by recognizing and analyzing cues and then following subsequent steps until a satisfactory outcome is reached.

Recognizing and Analyzing Cues

As part of recognizing and analyzing cues, the nurse should complete a physical examination and take the patient’s personal and family history of allergies. Findings from the physical examination may reveal any of the clinical manifestations previously. An assessment should also include the patient’s onset of symptoms after exposure to the suspected or known allergen.

Prioritizing Hypotheses, Generating Solutions, and Taking Action

After documenting the findings from the patient’s examination and history, the nurse should verify orders that may be received from the provider. Interventions may be aimed at improving symptoms, administering medications, and educating the patient about avoidance therapy and emergency measures should they be necessary. Nursing interventions for improving symptoms may include administering medications and eliminating identified or suspected triggers causing a reaction. Medications may include epinephrine in extreme cases or when patients have difficulty breathing. Antihistamines or corticosteroids may also be prescribed. Since anaphylaxis is a risk with any allergic reaction, the nurse must assess and be ready to intervene in the event of this type of emergency. The nurse should also educate the patient on a variety of topics: signs and symptoms that indicate a medical emergency; instructions on how to use an EpiPen and read ingredients and food labels; and the importance of reporting their allergy to other people, including health care providers and servers at restaurants, and of asking questions before eating food they did not prepare.

Evaluation of Nursing Care for Patient with a Food Allergy

Evaluation is an essential part of the nursing process. The nurse should compare observed outcomes against expected outcomes. This allows the nurse to evaluate for signs of improvement, decline, or no change. The nurse would then use their judgment to assess whether the interventions were effective or if other interventions are needed.

Evaluating Outcomes

The nurse will want to evaluate expected outcomes for patients with food allergies. The nurse can determine if symptoms have improved based on clinical examination as well as patient verbalization. The nurse can confirm comprehension by having the patient verbalize or reiterate what they have learned regarding diagnosis, symptoms, medications, and allergen avoidance measures. The patient should also be able to demonstrate how to properly administer their medications and be able to describe signs and symptoms such as anaphylaxis, difficulty swallowing, wheezing, difficulty breathing, peripheral tingling, and urticaria.

Medical Therapies and Related Care

The primary management for food allergies includes eliminating the allergen from the diet. Medications may be prescribed for those who cannot eliminate exposure or those who do not benefit from avoidance therapy. Medications include antihistamines, adrenergic agents, H1 blockers, corticosteroids, and cromolyn sodium. All patients with food allergies should have an EpiPen. A medical alert bracelet should also be worn. Service animals can be trained to recognize allergens that pose a threat to their owner. Service animals can scan foods and other areas for the scent of an allergen and alert their owner of the potential threat. Service animals would not be used for those with known allergies to pet dander. It is important to note that those with allergies can develop an allergy to an animal, so this option should be used with caution (US Service Animals Blog, 2022).