What is the treatment for a suspected moderate allergic reaction in the setting of influenza-like symptoms?

From the Guidelines

For a suspected moderate allergic reaction in the setting of influenza-like symptoms, administer an oral antihistamine like diphenhydramine (Benadryl) 25-50 mg immediately, as it is the most appropriate initial treatment according to the guidelines for anaphylaxis treatment 1. When managing a moderate allergic reaction, it is crucial to prioritize the patient's airway, breathing, and circulation (ABCs) and to monitor their vital signs closely.

• Remove any potential allergen if identifiable to prevent further exposure.
• Monitor symptoms closely for at least 4-6 hours, watching for signs of worsening such as difficulty breathing, severe swelling, or lightheadedness.
• Apply cool compresses to any hives or swelling to help alleviate symptoms.
• Stay hydrated and rest to help the body recover from the allergic reaction and influenza-like symptoms. For fever or pain from flu symptoms, acetaminophen (Tylenol) is generally safer than NSAIDs, which might worsen allergic reactions in some people 1. If symptoms worsen, particularly breathing difficulties, facial swelling, or confusion, seek emergency medical care immediately, as these could be signs of a severe allergic reaction or anaphylaxis, which requires prompt treatment with intramuscular epinephrine and other supportive measures 1. In addition to antihistamines, systemic steroids may be given for severe anaphylaxis, asthma, and significant generalized urticaria/angioedema, although the evidence for this is not clear 1. It is essential to note that while the provided study focuses on oral food challenge testing, the principles of treating allergic reactions, including the use of antihistamines and monitoring of vital signs, can be applied to other contexts, such as influenza-like symptoms 1.

From the FDA Drug Label

Emergency treatment of allergic reactions (Type I), including anaphylaxis, which may result from allergic reactions to insect stings, biting insects, foods, drugs, sera, diagnostic testing substances and other allergens, as well as idiopathic anaphylaxis or exercise-induced anaphylaxis. For amelioration of allergic reactions to blood or plasma, in anaphylaxis as an adjunct to epinephrine and other standard measures after the acute symptoms have been controlled, and for other uncomplicated allergic conditions of the immediate type when oral therapy is impossible or contraindicated.

The treatment for a suspected moderate allergic reaction in the setting of influenza-like symptoms may involve epinephrine (IM) as the first line of treatment for emergency allergic reactions, including anaphylaxis 2.

• Epinephrine (IM) is used for emergency treatment of allergic reactions.
• Diphenhydramine (IV) may be used as an adjunct to epinephrine and other standard measures after the acute symptoms have been controlled, for amelioration of allergic reactions 3. However, the provided drug labels do not explicitly address the treatment of moderate allergic reactions in the setting of influenza-like symptoms.

From the Research

Treatment for Suspected Moderate Allergic Reaction

• The treatment for a suspected moderate allergic reaction involves the administration of epinephrine, which is the essential antianaphylactic drug in the pharmacologic treatment 4, 5, 6, 7.
• Epinephrine should be applied intramuscularly, and in severe cases, intravenous application can be considered 4, 6, 7.
• Additionally, glucocorticosteroids can be given to prevent protracted or biphasic courses of anaphylaxis, although they are of little help in the acute treatment 4.
• Histamine H(1)-antagonists can be valuable in mild anaphylactic reactions and should be given intravenously if possible 4.
• Replacement of volume is crucial in antianaphylactic treatment, and crystalloids can be used in the beginning, while colloid volume substitutes can be applied in severe shock 4.

Considerations for Influenza-like Symptoms

• In the setting of influenza-like symptoms, it is essential to distinguish between an allergic reaction and the symptoms of influenza itself 8.
• The diagnosis of anaphylaxis is purely clinical, and laboratory tests are of no help in the acute situation 4.
• The treatment for influenza involves the use of anti-influenza drugs, which may be considered if the patient presents within 48 hours of symptom onset 8.
• However, the treatment for a suspected moderate allergic reaction takes priority, and epinephrine administration should not be delayed 5, 6, 7.

Key Considerations

• Patients suffering from an anaphylactic episode should be observed over a period of 4-10 h according to the severity of the symptomatology 4.
• It is crucial to be aware of risk patients, such as those with severe uncontrolled asthma or under beta-adrenergic blockade 4.
• Educational programs for anaphylaxis have been developed, and patients should be trained on the nature of anaphylaxis, the major eliciting agents, and the principles of behavior and coping with the situation 4.