What is the approach to managing a case of allergy?

Approach to Managing a Case of Allergy

The approach to allergy management depends critically on whether the patient presents with acute anaphylaxis (requiring immediate intramuscular epinephrine) versus chronic allergic disease (requiring diagnostic confirmation followed by avoidance, pharmacotherapy, or immunotherapy). 1

Acute Anaphylaxis Management

If the patient presents with acute systemic allergic reaction, immediately administer intramuscular epinephrine as first-line therapy—this is non-negotiable and delays are associated with death. 1

Immediate Actions (Concurrent Steps)

• Eliminate additional allergen exposure 1
• Inject intramuscular epinephrine immediately (do not delay for any reason) 1
• Call for emergency help (911 or resuscitation team), but do not let this delay epinephrine administration 1

Secondary Interventions (Within Minutes)

• Place patient recumbent with lower extremities elevated (if tolerated) 1
• Provide supplemental oxygen 1
• Administer IV fluid resuscitation 1
• Repeat epinephrine dosing if suboptimal response—epinephrine remains first-line over adjunctive treatments like antihistamines or corticosteroids 1

Critical Pitfall

There is no evidence that prophylaxis with H1/H2-receptor antagonists or corticosteroids prevents or reduces anaphylaxis severity—these are adjunctive only, never substitutes for epinephrine. 1 The benefits of epinephrine far outweigh risks of unnecessary dosing, while delayed administration contributes to fatalities. 1

Diagnostic Approach for Non-Acute Presentations

Step 1: Establish IgE-Mediated vs Non-IgE-Mediated Disease

Obtain detailed history focusing on: 1

• Specific allergen exposures and temporal relationship to symptoms
• Symptom profile (skin, respiratory, gastrointestinal, cardiovascular involvement)
• Severity and reproducibility of reactions
• Response to previous treatments

Perform allergy testing to confirm sensitization: 1

• Immediate hypersensitivity skin testing is the preferred method for detecting specific IgE antibodies 1
• In vitro serum-specific IgE testing is useful when skin testing is contraindicated or unavailable 1
• Critical distinction: Positive IgE testing alone indicates sensitization, NOT clinical allergy—correlation with clinical symptoms and exposure is mandatory 1

Step 2: Identify the Culprit Allergen

For food allergies: 1

• Eliminate suspected allergenic food from diet as initial approach 1
• If ineffective, perform IgE-specific antibody or skin testing 1
• Oral food challenge should be performed to confirm diagnosis (gold standard) 1

For drug allergies: 1

• Skin testing for penicillin has high negative predictive value and should be performed when penicillin is indicated with limited alternatives 2
• Testing for other drugs has less established sensitivity/specificity 2

For perioperative allergic reactions: 1

• Obtain serum tryptase at time of reaction and later baseline sample 1
• Consider that two or more positive test modalities reduce false positive risk, particularly for neuromuscular blocking agents and chlorhexidine 1

Step 3: Rule Out Non-Allergic Mimics

Distinguish true allergy from: 1

• Food intolerance (non-immunologic adverse reactions like lactose intolerance) 1
• Chronic GABHS carriers with intercurrent viral infections (10.9% in children ≤14 years) 3
• Gastroesophageal reflux disease causing chronic throat irritation 3

Long-Term Management Strategy

Allergen Avoidance (Primary Strategy)

For confirmed IgE-mediated allergies, strict avoidance of the identified culprit is mandatory. 1, 4

For perioperative allergies: 1

• Inform all healthcare personnel to prevent accidental re-exposure (one-third of chlorhexidine-allergic patients are accidentally re-exposed) 1
• If emergency surgery is needed before investigation, favor regional/inhalational techniques to minimize IV drug exposures 1
• Avoid latex, chlorhexidine, neuromuscular blocking agents, and penicillin/cephalosporin antibiotics when possible 1

For food allergies: 4

• Maintain strict food avoidance and carry emergency epinephrine at all times 4
• Adolescents with peanut and tree nut allergies are at highest risk for life-threatening anaphylaxis 4

Pharmacotherapy (Adjunctive)

For chronic allergic conditions (rhinitis, asthma, dermatitis): 1

• Use when symptoms are not controlled by avoidance alone 1
• Consider when patients require high medication doses or multiple medications 1

Prednisone is FDA-indicated for: 5

• Severe or incapacitating allergic conditions intractable to conventional treatment 5
• Seasonal or perennial allergic rhinitis, bronchial asthma, contact dermatitis, atopic dermatitis, serum sickness, drug hypersensitivity reactions 5

Allergen Immunotherapy (Disease-Modifying)

Consider immunotherapy when: 1

• Positive IgE testing correlates with suspected triggers and patient exposure 1
• Symptoms are not well controlled by medications or avoidance measures 1
• Patient experiences adverse effects from medications or wishes to reduce long-term medication use 1

Do NOT give immunotherapy when: 1

• IgE testing is negative 1
• Positive IgE tests do not correlate with clinical symptoms or exposure 1

For insect venom anaphylaxis: 1

• Patients at risk for anaphylaxis should receive venom immunotherapy (90% success rate) 1, 6

Critical requirement: 1

• Asthma must be controlled at the time immunotherapy injection is administered 1

Emerging Therapies

For IgE-mediated food allergies with previous anaphylaxis: 4

• Xolair (omalizumab) can increase the threshold at which allergic reactions occur, providing protection against small accidental exposures 4
• Patient should still maintain strict avoidance and carry emergency epinephrine 4

Emergency Preparedness

All patients with confirmed IgE-mediated allergies must have: 4

• Anaphylaxis management plan with ready access to injectable epinephrine 4
• Training on recognizing early symptoms and self-administering epinephrine 1
• Understanding that epinephrine should be administered at first sign of systemic reaction, not delayed 1

Special Considerations for Uninvestigated Reactions

If patient has history of previous uninvestigated perioperative reaction: 1

• This is a known risk factor for recurrence during subsequent anesthetics 1
• For elective surgery with severe previous reaction: refer for specialized perioperative allergy investigation before surgery 1
• For urgent surgery: gather all available information and avoid all exposures that occurred before the previous reaction 1