How can you tell a flu from a common cold?
A common question that people ask doctors is whether their viral symptoms may be due to influenza (flu). There are a few key signs that help a doctor tell if it’s influenza- so here’s a quick guide to the common cold, influenza, and the main differences between them.
What is the Common Cold?
Around 200 different viruses can cause the common cold – that’s why, so far, it’s been impossible to develop an effective vaccine against it. On average, children will catch 6 to 8 colds per year, while adults get about 2 to 4 colds per year. The symptoms can last from a few days up to a week or two, and usually include runny nose, tiredness, and sometimes a sore throat. A headache and fever can occur but are less common.
What is Influenza?
Influenza, or flu, is a highly contagious viral infection that spreads from person to person by coughing or sneezing, or by contact with the influenza virus from a contaminated surface. It commonly causes fever, muscle aches, fatigue, headaches and sore throat, and in severe cases, can lead to pneumonia and death. Every year in Australia, flu is estimated to account for around 5000 hospital admissions and around 170 deaths. The flu vaccine is an effective way of reducing risk of infection, but it must be redeveloped each flu season, as the influenza virus mutates (changes) regularly, meaning that a vaccine from a previous year offers little or no protection the following year.
What is the difference between a cold and a flu?
Typical features of flu include:
- sudden onset of symptoms
- cough
- sore throat
- fever – often 38C or higher
- chills- quite common
- a runny or congested nose may be present, though tends to be less prominent in influenza than it is with a cold
- muscle or body aches are often quite significant in influenza (and are less of an issue with a common cold)
- headaches are common
- fatigue is usually present in influenza and can be quite severe
Common cold symptoms are usually milder than the symptoms of flu, and are suggested by the following:
- a more gradual onset than influenza
- runny or congested nose- this is usually a prominent symptom
- a fever is not typically present, though can occur in some cases
- headaches are less frequent
- aches and pains may occur, but also tend to be less severe than those experienced with influenza.
If you would like to learn more about the common cold, influenza, or the flu vaccine or if you have concerns about symptoms you are experiencing, speak to your doctor.
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Clinical review & governance
Medically reviewed by Dr AIFRIC BOYLAN
CEO
About Dr Aifric Boylan MB BCh BAO MICGP FRACGP DRCOG DCH Fellow of the Royal Australian College of General Practitioners, Dr Aifric Boylan is a general practitioner with more than 20 years' experience. She graduated in medicine from…
This health information has been clinically reviewed by an Australian doctor. Qoctor health pages are reviewed to support clear, evidence-informed guidance; they do not replace individual medical advice.
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