What is the recommended treatment for an otherwise healthy adult with mild to moderate influenza (flu) symptoms?

Treatment of Influenza Symptoms in Otherwise Healthy Adults

For otherwise healthy adults with mild to moderate influenza symptoms presenting within 48 hours of onset, oseltamivir 75 mg orally twice daily for 5 days is the recommended antiviral treatment, though symptomatic management alone is also reasonable given the modest benefit of antivirals in this population. 1, 2

Antiviral Therapy Decision Algorithm

When to Prescribe Oseltamivir

Initiate treatment within 48 hours of symptom onset for maximum benefit:

• The standard treatment window is within 48 hours of symptom onset for otherwise healthy outpatients 1, 2
• Treatment reduces illness duration by approximately 24-36 hours compared to placebo 3, 4, 5
• Greatest benefit occurs when started within 24 hours of symptom onset 5

Dosing:

• Adults: 75 mg orally twice daily for 5 days 1, 2
• Take with food to reduce nausea (occurs in 10-15% of patients) 3, 4, 2
• Adjust dose to 75 mg once daily if creatinine clearance <30 mL/min 1, 2

When Antivirals Are NOT Routinely Required

Previously well adults with uncomplicated influenza do not require antiviral treatment if:

• Symptoms are mild to moderate 1
• No high-risk conditions are present 1
• Patient preference favors symptomatic management alone 5, 6

Symptomatic Management (All Patients)

Recommended supportive care measures:

• Paracetamol (acetaminophen) or ibuprofen for fever, myalgias, and headache 1
• Rest and adequate fluid intake 1
• Avoid smoking 1
• Consider short course of topical decongestants, throat lozenges, or saline nose drops 1

Antibiotic Considerations

Antibiotics are NOT routinely indicated for uncomplicated influenza in previously healthy adults. 1, 3, 4

When to Consider Antibiotics

Add antibiotics if any of the following develop:

• Worsening symptoms after initial improvement (recrudescent fever or increasing dyspnea) 1, 3
• Clinical evidence of bacterial pneumonia on examination 3, 4
• Persistent high fever >3 days with productive cough 3

First-line antibiotic choices when indicated:

• Co-amoxiclav (amoxicillin-clavulanate) 1, 3
• Doxycycline or tetracycline 1, 3
• Clarithromycin or erythromycin (alternative for penicillin allergy) 1

When to Seek Further Medical Attention

Patients should re-consult immediately if they develop:

• Worsening symptoms after initial improvement 1, 3
• Persistent fever >3 days 3
• Increasing breathlessness or dyspnea 1
• Chest pain or productive sputum 1
• Altered mental status 1
• Inability to maintain oral intake 1

Important Clinical Caveats

Common pitfalls to avoid:

• Do not withhold oseltamivir in severely ill patients even if presenting beyond 48 hours 3, 4
• Do not prescribe antibiotics routinely for uncomplicated influenza—this promotes resistance without benefit 1, 4
• Do not use double-dose oseltamivir (150 mg twice daily)—no additional benefit demonstrated 4
• Aspirin is contraindicated in children under 16 years due to Reye's syndrome risk 1

Alternative antiviral agents:

• Zanamivir 10 mg (2 inhalations) twice daily for 5 days is an alternative, but avoid in patients with asthma or COPD due to bronchospasm risk 3, 4
• Baloxavir (single oral dose) may be considered as an alternative 3, 7

Expected Clinical Course

Typical uncomplicated influenza:

• Fever duration: 3-5 days without treatment 3
• Antiviral treatment shortens duration by approximately 1 day 3, 4, 5
• Patients should begin improving within 48 hours of starting oseltamivir 1