Cold vs Flu: How to Tell the Difference
Short answer: A cold creeps up over a day or two with a runny or blocked nose, sneezing and a sore throat, and you can usually keep going. Flu hits suddenly with fever, chills, aches, headache and exhaustion that puts you in bed. Both are viruses, so antibiotics don’t help, but flu can be serious.
Common cold
- Comes on gradually
- Runny or blocked nose, sneezing and sore throat are common
- Fever is rare in adults; aches are slight
- Usually better in 7 to 10 days
Flu (influenza)
- Comes on suddenly, often within hours
- Fever, chills, body aches, headache and exhaustion are usual
- Sneezing, blocked nose and sore throat only sometimes
- Worst for 3 to 5 days; tiredness and cough can last 2 weeks or more
Symptom by symptom
- Onset: cold, gradual; flu, abrupt.
- Fever: cold, rare; flu, usual (children with colds can run a temperature).
- Aches and chills: cold, slight aches, chills uncommon; flu, aches usual, chills fairly common.
- Tiredness and weakness: cold, sometimes; flu, usual and often severe.
- Sneezing and stuffy nose: cold, common; flu, sometimes.
- Sore throat: cold, common; flu, sometimes.
- Chest discomfort and cough: cold, mild to moderate; flu, common and can be severe.
- Headache: cold, rare; flu, common.
- COVID-19 and RSV can look like either. A rapid antigen test or a swab from your GP or pharmacy can tell them apart if it matters for treatment, work or vulnerable contacts.
Treatment
- Both: rest, fluids, and paracetamol or ibuprofen for fever and aches if needed. Honey can soothe a cough in adults and children over 1 year.
- Antibiotics don’t work on cold or flu viruses. They only help if a bacterial complication develops, such as some pneumonias.
- Flu antivirals (such as oseltamivir) work best started within 48 hours of symptoms. In healthy adults they shorten flu by about 17 hours on average; they matter most for people at higher risk of complications, so ask your GP early if that’s you.
- Stay home until the fever has gone and you feel better, to protect others. Wash hands and cough into your elbow.
Prevention: the flu vaccine
- Everyone aged 6 months and over is recommended to have a flu vaccine every year, because the circulating strains change.
- In Australia it’s free under the National Immunisation Program for children 6 months to under 5 years, pregnant women (any stage), Aboriginal and Torres Strait Islander people from 6 months, adults 65 and over, and people with certain medical conditions. Some states offer it free to more groups.
- Best time: from when vaccines arrive (usually March or April) before the peak season of June to September. It’s never too late in the season.
- There’s no vaccine for the common cold.
Who is at higher risk from flu
- Babies and young children, pregnant women, and adults 65 and over
- People with heart or lung disease (including asthma), diabetes, kidney disease or a weakened immune system
- Aboriginal and Torres Strait Islander people
See a doctor urgently or call 000 if
- Breathing is hard or fast, or lips look blue
- Chest pain, confusion, severe drowsiness or a seizure
- Not drinking, or few wet nappies or little urine
- A fever in a baby under 3 months
- You start to improve, then get worse with a new fever or cough (possible complication such as pneumonia)
- You’re in a higher-risk group and think you have flu: see your GP early, as antivirals work best in the first 48 hours
Common questions
How can I tell if I have a cold or the flu?
Speed and severity are the biggest clues. A cold comes on gradually with a runny nose, sneezing and sore throat. Flu comes on suddenly with fever, chills, body aches, headache and exhaustion. Only a test can confirm flu.
How long does the flu last compared with a cold?
A cold usually clears in 7 to 10 days. Flu symptoms are worst for 3 to 5 days, but tiredness and cough can hang around for 2 weeks or more.
Do antibiotics help a cold or flu?
No. Both are caused by viruses. Antibiotics only help if a bacterial complication develops. Flu antivirals can help some people, especially if started within 48 hours.
Who gets a free flu vaccine in Australia?
Under the National Immunisation Program: children aged 6 months to under 5, pregnant women, Aboriginal and Torres Strait Islander people from 6 months, adults 65 and over, and people with certain medical conditions. Some states fund extra groups.
Can the flu vaccine give you the flu?
No. Flu vaccines used in Australia don’t contain live virus that can cause flu. A sore arm, mild fever or aches for a day or two can happen as the immune system responds.
Sources
- CDC: Is it a cold or flu?. symptom comparison
- Australian Government: 2026 influenza vaccination consumer fact sheet. free NIP groups and timing
- Jefferson T et al. Neuraminidase inhibitors for preventing and treating influenza. Cochrane 2014. oseltamivir shortened symptoms by 16.8 hours in adults
- Royal Children’s Hospital Melbourne: Fever in children