How long does the flu typically last and what is the recommended treatment?

Flu Duration and Treatment

Uncomplicated influenza typically resolves in 3-7 days, though cough and malaise can persist for more than 2 weeks. 1

Duration of Illness

Acute Phase

• The acute febrile illness usually lasts 3-7 days in most patients with uncomplicated influenza 1
• Fever, myalgia, headache, and severe malaise are most prominent during the first 3-4 days 2
• Adults remain infectious from 1 day before symptom onset through approximately 5 days after illness begins 1, 3

Prolonged Symptoms

• Cough and malaise commonly persist for more than 2 weeks after the acute illness resolves 1
• This extended recovery period occurs even in otherwise healthy individuals 1

Special Populations with Longer Duration

• Young children can shed virus and remain infectious for 10 or more days after symptom onset 1, 3
• Immunocompromised patients may experience viral shedding for weeks to months, far longer than typical patients 1, 3
• These high-risk groups also experience more severe symptoms for prolonged periods 1

Recommended Treatment

Antiviral Therapy Indications

Start antiviral treatment as soon as possible—ideally within 24 hours of symptom onset—for maximum benefit. 1, 4

Patients Who Should Receive Antivirals:

• All hospitalized patients with influenza, regardless of illness duration 1
• Outpatients with severe or progressive illness at any point 1
• High-risk patients including:
  • Children younger than 2 years 1
  • Adults ≥65 years 1
  • Pregnant women and those within 2 weeks postpartum 1
  • Patients with chronic medical conditions 1
  • Immunocompromised individuals 1

Treatment Window:

• Greatest benefit occurs when treatment starts within 24 hours of symptom onset 4
• Treatment may still be considered if started within 48 hours 1
• Antiviral drugs reduce illness duration by approximately 1 day in otherwise healthy patients 1

Specific Antiviral Regimens

Use a single neuraminidase inhibitor (NAI) as monotherapy—do not combine multiple antivirals. 1

First-Line Options:

• Oral oseltamivir for 5 days 1
• Inhaled zanamivir for 5 days 1
• Intravenous peramivir as a single dose 1

Duration Modifications:

• Standard treatment is 5 days for uncomplicated cases 1, 5
• Consider longer duration for immunocompromised patients or those with severe lower respiratory disease, as viral replication is often protracted 1
• Discontinue amantadine/rimantadine within 24-48 hours after symptom resolution, typically after 3-5 days total 1, 5

Important Caveats About Antivirals

• No antiviral has been proven to prevent serious complications like bacterial pneumonia or exacerbation of chronic diseases 1
• Evidence for effectiveness is based primarily on studies of uncomplicated influenza in otherwise healthy patients 1
• Limited data exist for high-risk populations, though treatment is still recommended 1

Supportive Care

Symptomatic Management:

• Adequate hydration 5
• Fever control with acetaminophen or ibuprofen 5
• Rest until symptoms improve 1

Monitoring for Complications:

• Investigate bacterial coinfection in patients with:
  • Initial presentation with severe disease (extensive pneumonia, respiratory failure, hypotension) 1
  • Deterioration after initial improvement 1
  • Failure to improve after 3-5 days of antiviral treatment 1

Isolation Recommendations

Patients should isolate at home until at least 24 hours after fever resolves without antipyretics. 3, 5

Key Isolation Criteria:

• Both conditions must be met: fever-free for 24 hours without medications AND symptoms improving 3, 5
• Do not return to work/school based solely on feeling better 3
• This typically translates to 5-7 days from symptom onset 3

Infection Control During Isolation:

• Cover coughs and sneezes 3
• Frequent handwashing 3, 5
• Clean frequently touched surfaces 3

Extended Isolation for High-Risk:

• Immunocompromised patients should remain isolated for 10+ days 3
• Young children may require isolation for 10+ days 3
• Healthcare and institutional settings may require longer isolation periods per facility policies 5

Common Pitfalls to Avoid

• Do not rely on fever alone in elderly or demented patients, as they may not mount adequate febrile responses 5
• Do not delay antiviral treatment waiting for laboratory confirmation in high-risk patients during flu season 1
• Do not use antivirals as a substitute for vaccination—they are adjuncts only 1
• Do not assume improvement means non-infectiousness—patients must meet the 24-hour fever-free criterion 3