Colds, flu and COVID-19 can feel very similar at first, especially in winter. This page explains what usually sets them apart, why testing is often the only way to know for sure, and what to do at each stage.
Emergency
Call triple zero (000) or go to your nearest emergency department if you or someone in your care has:
- difficulty breathing, or breathlessness even at rest
- chest pain or pressure
- blue or grey lips or face
- dizziness, confusion, or is very drowsy and hard to wake
- coughing up blood
Babies, children and people at higher risk
Babies, pregnant people, older adults and people with long-term health conditions can get worse quickly with any of these three illnesses. Have a lower threshold for calling 000 if this is you or someone in your care.
Call 000 or go to an emergency department if a baby under 3 months has a temperature above 38°C, or a baby/child is not drinking or feeding, or is not passing urine.
Key points
- Colds, flu and COVID-19 are caused by different viruses, but they can cause similar symptoms, especially a runny nose, cough and sore throat.
- Flu tends to come on suddenly and hits harder, with high fever and body aches. Colds are usually milder and build up gradually. COVID-19 can look like either.
- Symptoms alone are often not enough to tell the three apart. A rapid antigen test (RAT) or PCR test is the most reliable way to know.
- Most healthy adults with mild symptoms can manage at home with rest and fluids.
- People at higher risk, including older adults, pregnant people and people with long-term conditions, may be eligible for antiviral treatment, but it needs to start early.
- A Doccy consultation can help you work out which virus you might have, check whether you are eligible for antiviral treatment, and provide a medical certificate if you need one.
What is the difference between a cold, the flu and COVID-19?
They are three separate illnesses caused by different viruses. A cold is usually caused by a rhinovirus. Flu (influenza) is caused by the influenza A or B virus. COVID-19 is caused by a coronavirus called SARS-CoV-2.
All three spread through droplets when someone coughs, sneezes or talks, and from touching surfaces with the virus on them. How unwell you are, and whether you are in a higher-risk group, matters more than which virus it is. Any of the three can occasionally cause serious illness, even in people who are usually healthy.
When to see a doctor
If you or someone in your care has any of the signs in the emergency box at the top of this page, call triple zero (000) or go to your nearest emergency department.
Get an urgent GP appointment, or call healthdirect on 1800 022 222 for advice, if you or someone in your care has cold, flu or COVID-19 symptoms and:
- you are worried about your baby's or child's symptoms
- you are aged 65 or over
- you are pregnant or have recently given birth
- you have a long-term health condition, for example diabetes or a condition that affects your heart, lungs, liver, kidneys, brain or nerves
- you have a weakened immune system, for example because of chemotherapy or HIV
- you feel very unwell, or you are vomiting so much you cannot keep fluids down
- you feel short of breath
- you have signs of dehydration, such as dizziness when you stand up or passing less urine than usual
- you have a fever that is not coming down with paracetamol
- you have ear pain, or facial pain or pressure
- your symptoms do not improve after 7 days, or your cough keeps getting worse
If you are in a higher-risk group, try to be assessed in the first 1 to 2 days of symptoms, because antiviral treatment works best when started early.
If you are ever unsure, it is safer to seek medical advice, even if it turns out to be a cold.
Cold vs flu vs COVID-19: comparing the symptoms
Symptoms overlap a lot, and no symptom checklist can reliably tell the three apart. Testing is the only way to know for certain.
The common cold
A cold usually builds up over a day or two and stays in the nose and throat: a blocked or runny nose, sneezing, a mild sore throat and sometimes a cough. Fever is uncommon in adults, though children sometimes have a mild temperature. Most people still feel well enough to get on with their day. More than 200 viruses can cause a cold, which is why there is no vaccine. Most people recover within 7 to 10 days.
Influenza (the flu)
Flu tends to start suddenly, often with symptoms developing over hours. High fever and chills, severe muscle aches, exhaustion and a pounding headache are typical, along with a cough and sore throat. Many people feel too unwell to get out of bed for a few days, which is a useful clue. Children with flu sometimes also have stomach pain, nausea or vomiting. Flu season in Australia usually runs from June to September.
COVID-19
COVID-19 is the least predictable of the three. Loss of smell and taste are now less common than in the early years of the pandemic, and COVID-19 often looks like a cold or mild flu: fever, cough, sore throat, tiredness, muscle aches, and a runny or blocked nose. Most people have a mild illness, but it can lead to serious breathing problems, particularly in people who are older, pregnant, or living with a long-term health condition.
Why testing matters
A rapid antigen test (RAT) done at home can check for COVID-19. Combination RATs can test for COVID-19, influenza A and B, and respiratory syncytial virus (RSV) at the same time. They give a result in 10 to 20 minutes and are sold at pharmacies and supermarkets. A PCR test (a nose or throat swab sent to a laboratory) is more accurate, especially early in an infection.
Knowing which virus you have affects whether antiviral treatment is an option, how long to stay away from others, and whether people around you need to take extra care.
How to describe your symptoms to a doctor
Have these details ready, written down or on your phone:
- When it started: the exact day symptoms began. Antiviral eligibility is time-limited.
- How it started: suddenly over a few hours, or gradually over a day or two.
- Your symptoms: fever, cough, sore throat, aches, tiredness, changes to smell or taste, and any stomach symptoms.
- How unwell you feel: whether you can eat, drink and move around normally.
- Test results: any home RAT result and when you did it.
- Your risk factors: your age, whether you are pregnant, and any long-term health conditions.
What you can do at home for cold, flu and COVID-19
These tips are for mild illness only. If you develop any emergency signs, stop managing at home and seek medical help.
Rest as much as you can, especially in the first few days. Drink plenty of fluids; if your urine is dark, you need to drink more. Paracetamol or ibuprofen can help with fever, aches and headache. Follow the instructions on the packet and ask a pharmacist if you are not sure what is suitable for you.
For a sore throat, try warm drinks with honey (not for babies under 12 months), throat lozenges, or gargling with warm salty water. Saline nasal sprays or drops can ease a blocked nose.
Stay home while you are unwell, especially in the first few days when you are most infectious. This protects people who might get much sicker than you, such as older adults, pregnant people and people with long-term illnesses.
Seek medical advice if you notice any of the signs listed in "When to see a doctor".
Tests and treatment for cold, flu and COVID-19
A doctor will ask about your symptoms and when they began. In person, they may check your temperature, look at your throat and ears, and listen to your chest. They may suggest a RAT or PCR test, and occasionally a chest x-ray if they are worried about complications (for example a lung infection).
Colds: there is no antiviral treatment. Care focuses on rest, fluids and symptom relief.
Antibiotics do not treat any of these three illnesses, because they are caused by viruses, not bacteria.
Antivirals do not cure flu or COVID-19, but they lower the risk of severe illness and hospital admission. They work best when started early: within 48 hours of flu symptoms starting, or within 5 days for COVID-19.
Flu: your doctor may consider a flu antiviral medicine, such as oseltamivir (Tamiflu), if you are at higher risk of complications. This includes people aged 65 and over, pregnant people, people with long-term heart, lung or kidney disease or diabetes, people with a weakened immune system, and people in residential aged care. Flu antivirals usually need a private prescription, so ask your doctor or pharmacist about the cost. Read more in our Influenza article.
COVID-19: PBS-subsidised antiviral tablets, such as Paxlovid, are available if you are:
- aged 70 or over
- aged 50 or over with two or more risk factors for severe illness
- an Aboriginal or Torres Strait Islander person aged 30 or over with one risk factor
- aged 18 or over with a moderately to severely weakened immune system
- aged 18 or over and previously in hospital with COVID-19, and now reinfected
These medicines are not usually given to children, and they are not suitable during pregnancy or breastfeeding, or for some people with kidney or liver disease. PBS criteria are reviewed from time to time, so talk to your doctor as soon as you test positive or develop symptoms. Read more in our COVID-19 article.
Vaccination: your best protection against flu and COVID-19
There is no vaccine for the common cold. Vaccination is one of the most effective ways to lower your risk of severe flu or COVID-19.
For flu, it is recommended that everyone over the age of 6 months gets a flu vaccine every year, ideally from April so you are protected before winter. It is free under the National Immunisation Program for children aged 6 months to under 5 years, adults 65 and over, pregnant people, Aboriginal and Torres Strait Islander people aged 6 months and over, and people with certain medical conditions. Some states offer free vaccines to other groups, so check with your GP or pharmacy.
For COVID-19, the Australian Technical Advisory Group on Immunisation (ATAGI) recommends a COVID-19 vaccine:
- adults aged 75 and over: a dose every 6 months
- adults aged 65 to 74: a dose every year
- adults under 65 with a severely weakened immune system or certain medical conditions: a dose every year
- other adults under 65: can consider a dose after talking to their doctor
- pregnant people: can consider one dose from 20 weeks of pregnancy
From 1 October 2026, COVID-19 vaccines are free under the National Immunisation Program for adults aged 65 and over and people with a severely weakened immune system. This advice is reviewed regularly, so check with your GP or pharmacist about what applies to you.
You can have your flu and COVID-19 vaccines on the same day.
How Doccy doctors can help
A Doccy consultation can help you work out whether your symptoms sound like a cold, flu or COVID-19, and what to do next. A Doccy consultation can:
- talk through your symptoms and history
- advise whether a home rapid antigen test (RAT), or a PCR test through your GP, makes sense for you
- check whether you meet the criteria for antiviral treatment for flu or COVID-19, and prescribe it if you are eligible and it is appropriate
- give self-care advice and tell you which warning signs to watch for
- provide a medical certificate for work, study or caring for someone
A Doccy consultation is not suitable if you have any of the emergency signs at the top of this page. These need checks that cannot be done remotely, such as measuring your oxygen levels. Call triple zero (000) or go to your nearest emergency department instead.
Resources and support
healthdirect offers a free symptom checker and a 24-hour nurse helpline on 1800 022 222 if you are unsure what to do.
National Immunisation Information Line (1800 671 811) can answer questions about flu and COVID-19 vaccine eligibility and where to get vaccinated.
Your state or territory health department can confirm local vaccination programs in your area.
These services and websites can provide extra information, but they do not replace advice from your own doctor.
- healthdirect. Colds. 2024. https://www.healthdirect.gov.au/colds
- healthdirect. Flu (influenza). 2024. https://www.healthdirect.gov.au/flu
- healthdirect. COVID-19. 2026. https://www.healthdirect.gov.au/covid-19
- healthdirect. Antivirals for flu (influenza) and COVID-19. 2025. https://www.healthdirect.gov.au/antivirals-for-influenza-and-covid-19
- Australian Immunisation Handbook. Influenza (flu). https://immunisationhandbook.health.gov.au/contents/vaccine-preventable-diseases/influenza-flu
- Australian Technical Advisory Group on Immunisation (ATAGI). Statement on transition of COVID-19 vaccines to the National Immunisation Program. 2026. https://www.health.gov.au/sites/default/files/2026-09/atagi-statement-on-transition-of-covid-19-vaccines-to-the-national-immunisation-program.pdf