Treatment of Fever and Classic Flu Symptoms
For a patient with fever and classic flu symptoms without an allergic reaction, initiate oseltamivir 75 mg twice daily for 5 days if the patient presents within 48 hours of symptom onset, combined with acetaminophen or ibuprofen for symptomatic relief. 1, 2, 3
Antiviral Therapy Decision Algorithm
Timing is critical for antiviral effectiveness:
- Start oseltamivir only if symptoms began ≤48 hours ago - this is when antiviral therapy provides maximum benefit by reducing illness duration by approximately 24 hours 1, 3, 4
- Do NOT initiate antivirals if symptoms started >48 hours ago in otherwise healthy patients, as the window for effective treatment has closed 5
- The standard adult dose is oseltamivir 75 mg every 12 hours for 5 days 1, 2
- Reduce dose to 75 mg once daily if creatinine clearance is <30 mL/min 1
Exception for delayed treatment: Severely ill or immunocompromised patients may benefit from antiviral therapy started after 48 hours, though evidence is limited 1, 5
Symptomatic Management
Antipyretic therapy should be initiated immediately:
- Acetaminophen or ibuprofen for fever, headache, and myalgia 6, 3
- Both medications are equally effective for fever reduction 7
- Never use aspirin in children due to Reye's syndrome risk 1
- Encourage adequate oral fluid intake to prevent dehydration 6
- Advise rest to reduce metabolic demands 6
Antibiotic Considerations
Do NOT routinely prescribe antibiotics for uncomplicated influenza:
- Standard antibiotics are not indicated for viral influenza without evidence of bacterial superinfection 1, 5, 6
- Most patients with classic flu symptoms do not require antibiotics 1
Consider antibiotics only if the patient develops:
- Worsening symptoms after initial improvement (recrudescent fever or increasing dyspnea) 1, 5
- Signs of bacterial pneumonia: new fever after improvement, purulent sputum, respiratory distress 5
- Lower respiratory tract features in high-risk patients 1
If antibiotics become necessary, preferred oral regimens include:
- Co-amoxiclav (covers S. pneumoniae and S. aureus) 1
- Doxycycline as alternative 1
- These provide coverage for influenza-related bacterial complications including S. aureus 1
Monitoring and Red Flags
Instruct patients to seek immediate medical attention for:
- Increasing shortness of breath or respiratory distress 5, 6
- Persistent high fever beyond 3 days 1
- Confusion or altered mental status 6
- Chest pain 6
- Inability to maintain oral intake 6
Bacterial superinfection typically develops 4-5 days after initial influenza symptoms and presents with new or worsening fever, increasing dyspnea, or purulent sputum 5
Common Pitfalls to Avoid
- Do not delay oseltamivir while waiting for laboratory confirmation - the diagnosis should be made clinically when influenza is circulating in the community 3, 4
- Do not prescribe antibiotics prophylactically without evidence of bacterial infection, as this promotes resistance without proven benefit 5, 6
- Do not continue to offer antivirals beyond 48 hours in otherwise healthy patients, as effectiveness is negligible 5, 3
- Patients with cough and fever together during influenza season have a 79% positive predictive value for influenza infection 8