Flu: Signs and symptoms

Flu: Signs and symptoms
Patient and clinician

Recognising the flu

The flu can cause severe illness and significant negative impacts on quality of life,1,2 so it helps to understand how to identify this viral disease.

Cold vs Flu graph

Signs and symptoms

Both colds and flu may share similar and overlapping symptoms,3,4 including:

  • Headache
  • Sore throat
  • Runny nose
  • Nasal and sinus congestion
  • Cough, usually dry5
  • Sneezing
  • Malaise4

The flu usually presents with sudden onset and may also cause additional symptoms such as:

  • High fever lasting for 3-4 days6
  • Severe myalgia
  • Fatigue and weakness that may last 2-3 weeks or more
  • Chills
  • Loss of appetite7-11

The symptoms also affect quality of life by reducing alertness,12,13 causing a negative mood,12,13 performance reduction,13 slower reaction times,14,15 and disturbed/poor sleep2, 14

An influenza infection has the potential to deteriorate into pneumonia and respiratory failure, and may be life-threatening.10,11

  • Questions to ask your patient

    Woman coughing

    Ask your patient:15

    • What symptoms have you been experiencing?
    • Have your symptoms been continuous?
    • How severe are the symptoms?
    • Did your symptoms improve and then worsen?
    • What, if anything, seems to improve the symptoms?
    • What, if anything, worsens the symptoms?
  • When to refer your patient for further care

    Female clinician

    The patient should be referred to a physician in the following scenarios, as they may potentially require prescription antibiotics:16

    • If symptoms do not improve within 10 days, or get better and then suddenly deteriorate, including a fever of over 38°C, green or yellow mucus, and face pain for >3 consecutive days – this may indicate a bacterial sinus infection
    • If symptoms include a cough with coloured mucus, a fever of over 38°C, chills, shortness of breath, and chest pain with deep inhalation – this may indicate bacterial pneumonia
    • If the main symptoms are fits of severe, rapid coughing that end with a “whoop” sound – this may indicate pertussis (whooping cough)
    • If symptoms include sudden throat pain, pain when swallowing, a fever of over 38°C, and swollen glands – this may indicate strep throat
    • If symptoms include severe headache, high fever, neck pain or stiffness, photophobia, or a purpura rash – this may indicate meningitis

    Patients should also be referred for:

    • Difficulty breathing, or wheezing
    • Cough for >3 weeks
    • Severe sore throat

Understanding the flu

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Find out about the causes of the flu.

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Learn how the flu should be managed.

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Overview of the flu

Find out more about influenza.

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Learning Lab

Find out more in the learning lab.

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The Panadol Cold & Flu range

Find out how the Panadol Cold & Flu range can help your patients.

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Patient care resources

Access a leaflet for your patients, which can help them understand the causes of the flu and how best to treat it.

Learn more