What medication is recommended for a cough associated with influenza (flu)?

Treatment of Flu-Associated Cough

For uncomplicated influenza with cough, symptomatic treatment with dextromethorphan is the preferred cough suppressant, while antibiotics should be reserved only for patients who develop bacterial complications such as pneumonia or worsening bronchitis. 1

Initial Management Approach

Antiviral Therapy First

• Oseltamivir 75 mg every 12 hours for 5 days should be initiated if the patient presents within 48 hours of symptom onset with fever >38°C and influenza-like illness 1
• Greatest benefit occurs when started within 24 hours of symptom onset 2
• Dose reduction to 75 mg once daily is required if creatinine clearance <30 ml/minute 1

Symptomatic Cough Management

• Dextromethorphan is the recommended cough suppressant for flu-associated cough 1, 3
• Dextromethorphan 20 mg is effective and has been shown to reduce cough intensity more effectively than codeine (p<0.0008) 4
• It is preferred over codeine due to its non-narcotic status, safety profile, and lack of significant side-effects 4
• Codeine is only recommended for chronic bronchitis, not for upper respiratory infections like influenza 1

When Antibiotics Are NOT Needed

Previously well adults with acute bronchitis complicating influenza, in the absence of pneumonia, do not routinely require antibiotics. 1

• Simple cough with mild fever should be managed at home with antipyretics and fluids 1
• Aspirin should be avoided in children under 16 years 1

When to Consider Antibiotics

Worsening Symptoms Without Pneumonia

• Consider antibiotics if previously well adults develop recrudescent fever or increasing dyspnea 1
• Patients at high risk of complications (see below) should receive antibiotics when lower respiratory features develop 1

High-Risk Patients Requiring Antibiotics

Patients at high risk of complications should be considered for antibiotics in the presence of lower respiratory features 1:

• Preferred oral regimen: Co-amoxiclav or tetracycline (doxycycline) 1
• Alternative: Clarithromycin or erythromycin for penicillin-intolerant patients 1
• Alternative: Fluoroquinolone with enhanced pneumococcal activity (levofloxacin 500 mg once daily or moxifloxacin 400 mg once daily) 1

Influenza-Related Pneumonia

For non-severe pneumonia:

• Oral co-amoxiclav or tetracycline is the preferred first-line therapy 1
• Macrolide (erythromycin or clarithromycin) or respiratory fluoroquinolone as alternatives 1
• Antibiotics should be administered within 4 hours of admission 1

For severe pneumonia:

• IV co-amoxiclav 1.2 g three times daily OR cefuroxime 1.5 g three times daily OR cefotaxime 1 g three times daily PLUS clarithromycin 500 mg twice daily IV or erythromycin 500 mg four times daily IV 1
• This combination provides coverage for Streptococcus pneumoniae and Staphylococcus aureus, which assume greater importance during influenza 1, 5

Critical Pitfalls to Avoid

Overuse of Antibiotics

• Do not prescribe antibiotics for simple flu-associated cough without evidence of bacterial superinfection 1
• The majority of flu-associated coughs are viral and will not benefit from antibiotics 1

Staphylococcus aureus Consideration

• Staphylococcus aureus assumes much greater importance during influenza outbreaks 1, 5
• For severe pneumonia not responding to initial therapy, consider adding vancomycin 1 g twice daily IV for MRSA coverage 1, 5
• Recent hospitalization increases MRSA risk 5

Inappropriate Cough Suppressant Selection

• Avoid codeine for upper respiratory infections; it is only recommended for chronic bronchitis 1
• Peripheral cough suppressants (levodropropizine, moguisteine) have limited efficacy in upper respiratory infections 1

Timing Considerations

• Antiviral therapy benefit decreases significantly after 48 hours from symptom onset 1, 2
• However, severely ill or immunocompromised hospitalized patients may still benefit from antivirals started >48 hours after onset 1