COVID vs Flu vs Cold: How to Tell the Difference and What You Can Take

COVID-19, influenza (the flu) and the common cold are all respiratory infections caused by viruses, and in the first day or two they can feel almost identical — fever, cough, sore throat, headache and tiredness show up in all three. That overlap is exactly why guessing from symptoms is unreliable. The single most useful step is a rapid antigen test (RAT) to settle the COVID question, because the answer changes who you should stay away from and whether antiviral treatment is worth discussing with your GP.

The Fastest Way to Tell Them Apart

Use this as a decision guide, not a diagnosis. The clues below shift the odds, but only a test confirms COVID. Loss of taste or smell is the standout clue: it is common with COVID and unusual with the flu or a cold (a blocked nose can dull smell temporarily, which is different from losing it).

Should You Test — and When?

A RAT is the quickest way to answer the COVID question at home, with a result in about 10-20 minutes. RATs are widely sold at Australian pharmacies and supermarkets. They are less accurate than a laboratory PCR test, especially in the first day or two, when there may not be enough virus for the test to detect.

If your first RAT is negative but you still feel unwell, do not treat it as the final word — RATs are least accurate in the early stages of infection. It is sensible to repeat the test a day or two later while you have symptoms. If it matters that you get a definite answer — for example you are in a high-risk group or care for someone who is — ask your GP about a PCR test, which can pick up an infection a RAT misses early on.

How Long After Exposure Do Symptoms Start?

Incubation is the gap between catching a virus and feeling the first symptoms. It differs enough between the three to be a mild clue — a cold or flu usually shows up faster than COVID.

Because COVID can take up to two weeks to appear, you can feel fine for days after an exposure and still develop it later — another reason a single early negative RAT is not reassurance on its own.

Can You Have COVID and the Flu at the Same Time?

Yes. It is possible to be infected with COVID-19 and influenza at once — sometimes nicknamed 'flurona'. It is uncommon, but it can happen because they are different viruses that circulate together over the Australian winter. A positive RAT confirms COVID but does not rule out flu on top, so if you are severely unwell or high-risk, your GP may test for both. The practical takeaway is the same: rest, fluids, symptom relief, and medical advice early if you are in a higher-risk group.

Do You Still Need to Isolate for COVID in 2026?

There is no national law requiring you to isolate if you test positive for COVID-19. Current advice is that you stay home while you are unwell and until your acute symptoms (fever, sore throat, cough, runny nose) have gone — usually around 5 to 7 days. It is strongly recommended you avoid visiting hospitals, aged care and disability facilities, and anyone at higher risk of severe illness, for at least 7 days.

Antivirals: What Actually Treats the Virus

Antivirals are prescription-only medicines that act on the virus itself, unlike the OTC products further down, which only ease symptoms. They work best when started early — within about 48 hours for the flu and within 5 days of symptoms starting for COVID — and are aimed at people at higher risk of becoming seriously unwell, not the general public.

PBS-subsidised COVID antivirals are for specific higher-risk groups, and the thresholds are narrower than many people assume: people aged 70 and over; people aged 50 and over with two or more risk factors for severe disease; Aboriginal and Torres Strait Islander people aged 30 and over with one risk factor; and adults 18 and over who are moderately to severely immunocompromised, or who were previously hospitalised with COVID-19 and have been reinfected. Eligibility rules change, so check your situation with your GP or at pbs.gov.au rather than assuming. If you think you may be eligible, contact your GP as soon as symptoms start, because the treatment window is short.

What You Can Take for Symptoms at Home

For a cold, the flu or mild COVID managed at home, over-the-counter medicines relieve the symptoms that bother you most — they do not treat or cure the virus. Match the medicine to the symptom rather than reaching for everything at once.

Fever, headache and body aches

Paracetamol is the usual first choice and is gentle on the stomach. Ibuprofen, an anti-inflammatory, is an alternative that can help with aches and sinus pain — take it with food. Both bring down fever.

Blocked or runny nose

A pseudoephedrine decongestant (kept behind the pharmacy counter — you will need to show ID) is the most effective oral option for a blocked nose. Saline sprays and rinses are a drug-free alternative that suit most people, including when you would rather avoid a decongestant.

Sore throat and cough

Throat lozenges, warm honey-and-lemon drinks and simple gargles ease a sore throat. For a cough, plain relief such as honey is reasonable — but never give honey to a baby under 12 months. Cough and cold medicines have limited evidence and are not suitable for children under 6.

Several symptoms at once

Combination cold and flu tablets bundle a few ingredients into one dose, which can be convenient. Most already contain paracetamol, so do not take a separate paracetamol product on top — doubling up is a common way Australians accidentally exceed the safe daily limit of 4g. Always read the label to see what is inside.

When to See a Doctor

See your GP sooner rather than later if you are in a higher-risk group — over 65, pregnant, very young, Aboriginal or Torres Strait Islander, or living with a chronic condition — because antiviral treatment for the flu or COVID is only useful if started within the first few days. The exception is a baby under 3 months with a fever: that is an emergency department visit, not a GP booking.

Frequently Asked Questions

How do I know if I have COVID, the flu or a cold?

You cannot be sure from symptoms alone, because all three share fever, cough, sore throat and fatigue. A rapid antigen test is the only at-home way to confirm COVID, though a negative result early in an illness does not rule it out — retest a day or two later, or ask your GP about a PCR. As rough clues, a sudden high fever with severe body aches leans towards flu, a gradual runny nose and sneezing leans towards a cold, and loss of taste or smell leans towards COVID.

Can you have COVID without a fever?

Yes. Plenty of people have COVID with no fever at all — a scratchy throat, runny nose, headache or tiredness may be the only signs, which is one reason it can be mistaken for a cold. If you have any respiratory symptoms, a RAT is worth doing even without a temperature.

How many days after symptoms should I RAT test?

You can test as soon as symptoms appear, but a very early RAT can be negative before there is enough virus to detect. If the first test is negative and you still feel unwell, repeat it a day or two later while symptoms persist. Ask your GP about a PCR test if a definite answer matters.

What is the difference between Paxlovid and Tamiflu?

They treat different viruses. Tamiflu (oseltamivir) is an antiviral for influenza, ideally started within 48 hours. Paxlovid (nirmatrelvir plus ritonavir) is an antiviral for COVID-19, started within 5 days of symptoms. Both are prescription-only and aimed at people at higher risk of severe illness. Paxlovid interacts with many common medicines, so your GP will review what else you take before prescribing it.

What medicine can I take for COVID symptoms at home?

For mild COVID managed at home, the same OTC relief used for a cold or flu applies: paracetamol or ibuprofen for fever and aches, a decongestant or saline for a blocked nose, and lozenges or honey for a sore throat (never honey for a baby under 12 months). These ease symptoms only — they do not treat the virus. Rest and fluids matter just as much. See a doctor if you are high-risk or your breathing is affected.