Flu: Signs and symptoms
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.
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 sleep.2,14
An influenza infection has the potential to deteriorate into pneumonia and respiratory failure, and may be life-threatening.10,11
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Questions to ask your patient
![Woman coughing]()
Ask your patient15:
- 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?
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When to refer your patient for further care
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The patient should be referred to a physician in the following scenarios, as they may potentially require prescription antibiotics16:
- 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
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.
