What are the symptoms and management strategies for a patient with a history of allergies and asthma suspected of having influenza?

Influenza Symptoms and Management in Patients with Allergies and Asthma

Classic Influenza Symptoms

Influenza presents with abrupt onset of fever, cough, chills or sweats, myalgias, and malaise, which distinguishes it from other respiratory infections. 1

The hallmark clinical features include:

• Fever (typically ≥100°F, though in elderly patients >97.5°F is considered significant) 2, 1
• Respiratory symptoms: cough, nasal congestion, sore throat, or coryza 2, 1
• Systemic symptoms: myalgias, chills/sweats, malaise, fatigue, and headache 2, 1

For most outpatient presentations, the diagnosis is made clinically without laboratory confirmation. 1 However, rapid molecular assays are preferred when testing is indicated, particularly in hospitalized patients or when confirmation will change treatment decisions. 1

Critical Considerations for Patients with Asthma and Allergies

Patients with asthma are at significantly increased risk for influenza-associated complications and should receive annual inactivated influenza vaccination, though vaccination should not be expected to reduce asthma exacerbation frequency during influenza season. 3, 4

Asthma-Specific Risks and Monitoring

• Asthma was the most common comorbidity among patients hospitalized with pandemic H1N1, affecting 29% of hospitalized cases 5
• Viral respiratory infections, particularly influenza, are the environmental factor that contributes most to the development, persistence, and severity of asthma 3
• Patients with influenza and asthma, particularly pediatric patients, may be at increased risk of confusion or abnormal behavior early in their illness 2
• Monitor closely for signs of abnormal behavior and neuropsychiatric events 2

Rare but Important: Anaphylaxis Risk

Patients with both environmental/food allergies and asthma are at increased risk for fatal anaphylactic reactions. 6 While extremely rare, influenza infection itself has been reported to trigger anaphylaxis in a pediatric patient with atopy and asthma. 7 An epinephrine auto-injector should be prescribed for patients with documented severe allergic reactions. 6

Antiviral Treatment Strategy

Treatment with oseltamivir should be initiated within 48 hours of symptom onset, with greatest benefit when started within 24 hours. 2, 1

Dosing and Duration

• Adults and adolescents: oseltamivir 75 mg orally twice daily for 5 days 2
• Pediatric patients (1-12 years): oseltamivir 2 mg/kg orally twice daily 2
• Treatment decreases illness duration by approximately 24 hours in otherwise healthy patients and may decrease risk of serious complications 2, 1

Evidence in Asthma Patients

• Among hospitalized asthma patients with influenza, those who received antiviral agents ≤2 days of admission had better outcomes (92% survival without ICU admission vs. 73% in those treated later) 5
• Early antiviral treatment is critical in hospitalized patients with suspected influenza, including those with asthma 5
• A trial in patients with chronic cardiac or respiratory disease showed more rapid cessation of febrile illness with oseltamivir, though time to alleviation of all symptoms was not significantly different 2

Important Safety Warnings

• Discontinue oseltamivir if serious skin/hypersensitivity reactions (Stevens-Johnson Syndrome, toxic epidermal necrolysis, erythema multiforme) occur or are suspected 2
• Only inactivated influenza vaccine (injection) should be used in asthma patients; live attenuated vaccine is contraindicated 4

Asthma Management During Influenza

Maintain aggressive asthma control during influenza illness, as viral infections are the primary trigger for asthma exacerbations. 3

Monitoring Asthma Control

Assess the following at each encounter:

• Symptom frequency (well-controlled = ≤2 days/week) 3
• Nighttime awakenings (well-controlled = ≤2 times/month) 3
• Short-acting β-agonist use (well-controlled = ≤2 days/week) 3
• Interference with normal activity (well-controlled = none) 3
• Peak flow or FEV1 (well-controlled = >80% predicted or personal best) 3

Controller Medication Considerations

• Inhaled corticosteroids (ICS) remain the most effective long-term control therapy and should be continued or optimized during influenza 3
• For patients on low-dose ICS with inadequate control, consider either increasing to medium-dose ICS or adding a long-acting β-agonist (LABA), but never use LABA as monotherapy 3
• Leukotriene receptor antagonists (montelukast) can be considered as alternative or add-on therapy 6, 8

Common Pitfalls to Avoid

• Do not underestimate asthma severity: 39-70% of patients report their asthma as well-controlled despite experiencing moderate symptoms 3
• Avoid β-blockers entirely in asthma patients, even β-selective medications, as antagonism of β-adrenoreceptors can induce bronchospasm 3
• Avoid aspirin and NSAIDs in patients with aspirin-sensitive asthma, which is relatively common and frequently associated with genetic variations 3

Environmental Control and Allergen Management

Identify and eliminate ongoing allergen exposures, as these are critical obstacles to achieving good asthma control during respiratory infections. 3

Key environmental interventions:

• Assess occupational history in adults with uncontrolled asthma, especially if symptoms improve on weekends and holidays 3
• Use skin or in vitro testing to assess sensitivity to perennial indoor allergens in patients with persistent asthma 3
• Implement multifaceted environmental control approaches, as single interventions are generally ineffective 3
• Advise all patients to avoid tobacco smoke exposure (active and passive) 3

When to Escalate Care

Refer to an asthma specialist if there are difficulties achieving or maintaining control, if step 5-6 therapy or omalizumab is considered, or if additional testing is indicated. 3

Specific red flags requiring urgent evaluation:

• Pneumonia on presentation (associated with 60% ICU admission rate in asthma patients with influenza vs. 27% in uncomplicated cases) 5
• Acute respiratory distress syndrome (24% of severe cases vs. 0% in uncomplicated asthma patients with influenza) 5
• Need for mechanical ventilation 5
• Persistent symptoms despite appropriate antiviral and asthma therapy 3