What is the appropriate prescription for acute febrile illness?

Management of Acute Febrile Illness

For acute febrile illness, the appropriate prescription depends on the underlying cause, with antiviral therapy (oseltamivir) recommended for influenza-like illness within 48 hours of symptom onset, and antibiotics only indicated for specific bacterial complications or high-risk patients. 1, 2

Initial Assessment and Diagnosis

• Define fever in adults as a single oral temperature ≥100°F (37.8°C), repeated oral temperatures ≥99°F (37.2°C), or an increase in temperature of ≥2°F over baseline 2
• Monitor vital signs including temperature, respiratory rate, pulse, blood pressure, mental status, and oxygen saturation at least twice daily 1, 2
• Consider hospital admission if the patient has two or more unstable clinical factors: temperature >37.8°C, heart rate >100/min, respiratory rate >24/min, systolic blood pressure <90 mmHg, or oxygen saturation <90% 1

Treatment Algorithm

1. Viral Influenza-Like Illness

• Antiviral therapy (oseltamivir) is indicated if all of the following criteria are met:

  • Acute influenza-like illness
  • Fever (>38°C)
  • Symptoms present for two days or less 1, 2

• Dosing of oseltamivir:

  • Standard dose: 75 mg every 12 hours for five days
  • Reduce dose to 75 mg once daily if creatinine clearance is less than 30 ml/min 1, 3
  • Immunocompromised or elderly patients who cannot mount an adequate febrile response may still be eligible despite lack of documented fever 1, 2

2. Uncomplicated Influenza (without pneumonia)

• Previously well adults with acute bronchitis complicating influenza do not routinely require antibiotics 1
• Consider antibiotics only if:
  • Symptoms are worsening (recrudescent fever or increasing dyspnoea)
  • Patient is at high risk of complications or secondary infection with lower respiratory features 1, 2

3. Influenza with Non-Severe Pneumonia

• Oral antibiotics are appropriate for most patients 1
• First-line antibiotic options:
  • Co-amoxiclav or a tetracycline (e.g., doxycycline) 1
• Alternative options (for penicillin intolerance):
  • Macrolide (clarithromycin or erythromycin) 1
  • Fluoroquinolone active against S. pneumoniae and S. aureus (levofloxacin or moxifloxacin) 1

4. Severe Influenza-Related Pneumonia

• Immediate parenteral antibiotics are required 1
• Consider hospital admission and intravenous antibiotics 1

5. Febrile Neutropenia (special case)

• Requires immediate broad-spectrum antibiotics 1
• If low-risk and apyrexial with ANC ≥0.5×10^9/l at 48 hours, consider changing to oral antibiotics 1
• If high-risk and apyrexial with ANC ≥0.5×10^9/l at 48 hours, aminoglycoside may be discontinued if on dual therapy 1

Supportive Care

• Ensure adequate hydration and nutritional support, especially in severe or prolonged illness 1, 2
• Provide supplemental oxygen if oxygen saturation falls below 90% 2
• Monitor for cardiac complications and volume depletion 2
• Consider antipyretic therapy in patients with cardiorespiratory or neurosurgical conditions, or if temperature exceeds 40°C 4

Follow-up Care

• Review patients 24 hours prior to discharge 1
• Consider follow-up clinical review for all patients who suffered significant complications or worsening of underlying disease 1, 2
• Provide patients with information about their illness, medications, and follow-up arrangements 1, 2

Common Pitfalls to Avoid

• Overtreatment with antibiotics in viral illnesses without evidence of bacterial infection 5
• Delayed treatment with antivirals (should be started within 48 hours of symptom onset for maximum benefit) 1, 3
• Failure to consider non-influenza causes of fever, especially in tropical settings where vector-borne diseases may be common 6, 7
• Inadequate monitoring of high-risk patients, which can lead to missed complications 1, 2