What is the management and treatment plan for a patient with suspected systemic allergies?

Management of Systemic Allergies

Acute systemic allergic reactions (anaphylaxis) require immediate intramuscular epinephrine injection as first-line treatment, with doses of 0.3-0.5 mg for adults and 0.01 mg/kg (maximum 0.3 mg) for children under 30 kg, administered into the anterolateral thigh and repeated every 5-10 minutes as necessary. 1

Immediate Emergency Management

First-Line Treatment

• Epinephrine is the only appropriate first-line treatment for anaphylaxis and should never be replaced by antihistamines or corticosteroids 2, 1
• Administer intramuscularly through the anterolateral thigh, even through clothing if necessary 1
• Monitor clinically for reaction severity and cardiac effects, with repeat doses titrated to effect 1
• Fatal anaphylactic reactions have been directly associated with delays in epinephrine administration 2

Supportive Measures

• Transport all patients to an emergency department for observation and additional treatment 2
• Secondary medications include antihistamines and systemic corticosteroids, but these only modify reactions and never substitute for epinephrine 2
• Severe cases may require intravenous saline or supplemental oxygen 2

Critical Timing Consideration

• Most severe systemic reactions occur within 30 minutes of allergen exposure 2, 3
• However, delayed reactions beyond 30 minutes do occur, requiring patient education on self-treatment 2, 4

Diagnostic Evaluation

Confirming IgE-Mediated Allergy

• Immediate hypersensitivity skin testing is the preferred diagnostic method over in vitro serum IgE testing 2, 3, 5
• Skin testing should only be performed when results will correlate with clinical history and suspected allergen exposure 2, 3
• For stinging insect hypersensitivity, skin testing should be performed at least 6 weeks after the reaction if initial tests are negative 2
• Baseline serum tryptase measurement is recommended in patients with severe allergic reactions and negative initial skin tests 2

Important Testing Principles

• The presence of specific IgE antibodies alone does not indicate clinical sensitivity—correlation with symptoms and exposure is mandatory 2, 5
• The degree of skin test or serologic sensitivity does not consistently correlate with reaction severity 2
• Never initiate treatment based solely on positive IgE tests without clinical correlation 5

Long-Term Management Strategy

Allergen Avoidance (Primary Approach)

• Complete avoidance of identified allergens is the cornerstone of management 5
• Provide detailed education on reading labels and recognizing hidden allergens 2, 5
• For food allergies, nutritional counseling with a specialized dietitian is mandatory, particularly when eliminating major food groups 5

Emergency Preparedness

• All patients with confirmed IgE-mediated allergies or anaphylaxis risk must carry epinephrine auto-injectors 2, 5
• Patients must be trained in proper use and indications for self-administered epinephrine 2
• Consider medical identification bracelets or necklaces 2
• Develop an individualized action plan for delayed systemic reactions 2

Allergen Immunotherapy Indications

When to Consider Immunotherapy

• Immunotherapy is highly effective (90-98%) for stinging insect hypersensitivity and should be recommended for all patients with systemic reactions and documented specific IgE 2, 3
• Consider for allergic rhinitis, allergic conjunctivitis, and allergic asthma when symptoms remain poorly controlled despite medications and avoidance measures 2, 3, 5
• Appropriate for patients requiring high medication doses, multiple medications, or experiencing adverse medication effects 2, 3

Absolute Requirements Before Starting

• Only clinically relevant allergens with documented specific IgE antibodies should be included 3, 5
• Patients must understand benefits, risks, costs, expected onset of efficacy, and duration of treatment 2
• Asthma must be controlled at the time of injection administration 2

Immunotherapy Administration Protocol

Safety Requirements (Non-Negotiable)

• All immunotherapy must be administered in a physician's office or healthcare facility equipped to recognize and treat anaphylaxis 2, 3
• Epinephrine, oxygen, antihistamines, corticosteroids, vasopressors, oral airway, and IV equipment must be immediately available 2
• Patients must wait 30 minutes after each injection before leaving the facility 2, 3
• Healthcare professionals administering injections must be trained in anaphylaxis recognition and treatment 2

Build-Up Phase

• Conventional schedules involve gradually increasing doses over 8-28 weeks with injections 1-3 times weekly 2, 3
• Accelerated schedules (rush or cluster) can achieve maintenance doses faster but carry increased systemic reaction risk 2, 3
• Target maintenance dose is 5-20 μg of major allergen for inhalant allergens and 100 μg for Hymenoptera venom 2, 3

Maintenance Phase

• Continue for at least 3-5 years to achieve long-term disease modification 2, 3
• For severe anaphylaxis (severe airway obstruction, shock, or loss of consciousness) to insect stings, consider indefinite immunotherapy 2
• Follow-up visits every 6-12 months to reassess symptoms, medication use, and clinical response 2

When to Withhold Injections

• Withhold immunotherapy during acute asthma exacerbations 2
• Consider measuring peak expiratory flow rate before each injection and withhold if low for that patient 2, 3
• Patients taking β-adrenergic blocking agents are at higher risk for severe reactions—this is a relative contraindication except for insect venom allergy where benefits may outweigh risks 2

Critical Pitfalls to Avoid

• Never delay epinephrine administration in favor of antihistamines or observation alone 2
• Do not initiate allergen avoidance or immunotherapy for positive IgE tests lacking clinical correlation 5
• Avoid unnecessary dietary restrictions that can lead to nutritional deficiencies 5
• Do not administer repeated immunotherapy injections at the same site due to vasoconstriction-induced tissue necrosis risk 1
• Patients with poorly controlled asthma are at higher risk for serious immunotherapy reactions—exercise caution 2
• Antihistamines should never be used for prevention of allergic reactions, only for symptom treatment 5