What are the management and treatment options for a patient with a history of infectious mononucleosis who is experiencing flu-like symptoms?

Management of Flu-Like Symptoms in Patients with Prior Infectious Mononucleosis

Treat this as acute influenza with standard supportive care and consider antivirals if presenting within 48 hours of symptom onset; the history of prior mononucleosis does not alter influenza management, as EBV remains latent after recovery and does not "reactivate" with flu infection.

Initial Assessment and Antiviral Decision

Consider oseltamivir 75 mg orally every 12 hours for 5 days if the patient meets all three criteria: acute influenza-like illness, fever >38°C, and symptomatic for ≤2 days 1. This recommendation applies regardless of mononucleosis history, as prior EBV infection does not increase influenza severity in immunocompetent patients 2.

• Start antivirals immediately based on clinical diagnosis without waiting for laboratory confirmation 3
• Elderly or immunocompromised patients may warrant treatment despite absent fever 1
• Reduce oseltamivir dose to 75 mg once daily if creatinine clearance <30 mL/min 1, 4

Symptomatic Management

First-line treatment is paracetamol (acetaminophen) for fever, myalgias, and headache 5. This provides the most favorable safety profile for antipyretic and analgesic effects 5.

• Use antipyretics to alleviate distressing symptoms, not solely to reduce temperature 5
• Continue treatment only while fever and discomfort persist 5
• Alternative: ibuprofen with caution 5
• Never use aspirin in patients under 16 years due to Reye's syndrome risk 5

Additional supportive measures include:

• Rest guided by the patient's energy level (enforced bed rest is unnecessary) 6
• Adequate hydration (up to 2 liters daily, not exceeding this amount) 5
• Avoid smoking 5
• Short-term topical decongestants, throat lozenges, or saline nose drops as needed 5
• For distressing cough: codeine linctus, codeine phosphate tablets, or morphine sulfate oral solution 5

Antibiotic Considerations

Do not routinely prescribe antibiotics for uncomplicated influenza without pneumonia 1, 7.

However, add antibiotics immediately if:

• Worsening symptoms develop (recrudescent fever or increasing dyspnea) 1
• Lower respiratory features appear in high-risk patients 1
• Clinical deterioration occurs after initial improvement 3

First-line oral antibiotic choices: co-amoxiclav or tetracycline 1, 3. Alternatives include macrolides (clarithromycin or erythromycin) or fluoroquinolones active against S. pneumoniae and S. aureus 1.

Monitoring Parameters

Track vital signs at least twice daily, more frequently in severe illness 1, 3:

• Temperature, respiratory rate, pulse, blood pressure 1
• Mental status, oxygen saturation, inspired oxygen concentration 1
• Early Warning Score system provides convenient systematic monitoring 1, 3

When to Seek Immediate Re-evaluation

Advise patients to return immediately if they develop 5:

• Shortness of breath at rest or with minimal activity
• Painful or difficult breathing
• Coughing up bloody sputum
• Drowsiness, disorientation, or confusion
• Fever persisting 4-5 days without improvement
• Initial improvement followed by recurrence of high fever

Activity Restrictions

The history of mononucleosis does not require ongoing activity restrictions unless splenomegaly persists from the prior EBV infection 2, 6, 8. If splenomegaly is still present from mononucleosis, avoid contact sports or strenuous exercise for 8 weeks or until splenomegaly resolves 2. Standard influenza does not require prolonged activity restriction beyond symptom-guided rest 5, 6.

Critical Pitfalls to Avoid

• Never delay oseltamivir while awaiting laboratory confirmation - clinical diagnosis suffices and early treatment maximizes benefit 3
• Never withhold antibiotics if bacterial superinfection is suspected - empiric coverage must start immediately 7, 3
• Never assume prior mononucleosis creates ongoing immunosuppression - most patients recover completely with normal immune function 2, 8
• Do not confuse this scenario with active/acute mononucleosis - the question addresses prior (resolved) mononucleosis, not concurrent dual infection 2, 8

Vaccination Timing

Oseltamivir is not a substitute for annual influenza vaccination 4. Avoid live attenuated influenza vaccine (LAIV) within 2 weeks before or 48 hours after oseltamivir administration unless medically necessary, as oseltamivir may inhibit LAIV replication and reduce efficacy 4.