Flu, Cold, or COVID-19? How to Tell the Difference

lu (influenza) and COVID-19 are both viral respiratory infections that share many symptoms, including sore throat, cough, fatigue and a runny nose. Because they can feel so similar at first, it’s not always easy to know which one you have. 

A “cold” can be caused by any virus that affects the respiratory system, most commonly rhinovirus but also other viruses such as RSV, and even COVID-19 and Influenza.

Understanding the differences are important, as it helps you decide when to get tested, when to stay home, and when to seek medical care. This article will guide you through the key symptoms, how each illness spreads, and what steps to take to recover safely while protecting your family, workplace and community.

Why These Illnesses Get Confused

These illnesses all affect the respiratory system and may begin with similar early signs. However, how each virus causes symptoms can differ based on several factors, including the specific strain, your immune system, vaccination status, age, and any underlying health conditions. 

It’s important to remember that sometimes symptoms alone aren’t enough for an accurate diagnosis. Speaking with your GP to discuss testing may help confirm the cause and guide the best course of action.

Cold vs Flu vs COVID-19: Definitions & Symptom Comparison

Cold

A cold is a mild infection of the upper respiratory tract (nasal passages, sinuses and throat) that will usually resolve on its own with simple rest and self care. It can be caused by any virus that affects the respiratory system, such as rhinovirus or RSV. COVID-19 and Influenza can cause colds as well. 

Common signs include a runny nose, sneezing, sore throat, and mild cough. 

Flu

This is an illness caused by influenza viruses that typically comes on suddenly. It is usually more severe than a cold and can cause symptoms like high fever, body aches, fatigue, chills, and sore throat. Many healthy or immunized people may experience influenza as a cold. However, unlike a cold caused by other viruses, the flu can lead to more serious complications, especially in vulnerable groups such as young children, pregnant women, older adults and people with weakened immune systems and chronic medical conditions. More than 1000 deaths in Australia during 2024 were associated with influenza virus (ABS 2025).

COVID-19

This is caused by the SARS-CoV-2 virus. Symptoms can vary depending on the variant and individual, but common signs include cough, fever, fatigue. Many people may experience reduced taste or smell.  In many people COVID-19 can cause symptoms like a cold or the flu. However, many people who are elderly or living with chronic illness are at higher risk of complications of COVID-19. In 2024 over 4000 deaths in Australia were associated with COVID-19 infection (ABS 2025).

Side-by-Side Symptom Table

This quick visual comparison can help you understand the key differences in symptoms for the flu, cold, and COVID-19. Keep in mind that symptoms can vary based on the individual, the virus strain, and other factors. For more details, check out our full Flu Symptoms blog.

How to Interpret the Symptoms

It is not possible to tell from symptoms alone whether you have COVID-19, Influenza (flu) or a cold from another virus, because many of the symptoms are the same (CDC 2024). 

Often the most important clue can be recent close contact with someone who has tested positive for influenza or COVID-19.

However if you are concerned about your symptoms or if they are not improving, your GP might suspect influenza or COVID-19 from particular symptoms: 

If you notice sudden high fever or body aches, this can be a clue for the flu. If you lose your sense of taste or smell, this can suggest COVID-19. Keep in mind that symptoms can overlap, so this table is just a general guide. If you’re unsure, it’s important to get tested or talk to your GP

Illness Timeline: Onset and Recovery

Onset Speed

Recent contact with someone who has tested positive for COVID-19 or Influenza can be an important clue when diagnosing these conditions. The speed at which symptoms appear can help you identify the illness. However, it's not a definitive way to diagnose, as symptoms can vary depending on the strain and individual factors.

Duration of Symptoms

The duration of symptoms will depend on how good your immune system is at fighting off the virus causing the symptoms. Immunization is an important way to train your immune system to do this. Most colds and uncomplicated flu and COVID-19 should be clearly improving by about a week. You should contact your GP as soon as possible if symptoms continue to worsen, if you feel concerned, or if they persist beyond a week.

How to Stay Protected from the Flu, Cold & COVID-19

Stay Up to Date with Vaccinations

Getting vaccinated each year is one of the best ways to protect yourself and others from serious illness. The flu vaccine is updated annually to match circulating strains and is especially important before flu season. COVID-19 boosters are also recommended to maintain immunity, particularly for older adults, people with underlying health conditions, and those working in healthcare or aged care.

Vaccines help reduce the severity of illness if you do get sick and lower the risk of spreading the virus to others. Staying current with your vaccinations helps protect you, your family, and the wider community.

Learn more about our Flu Vaccination Services. 

Practise Good Hygiene

Simple hygiene habits make a big difference in reducing the spread of viruses. Regular handwashing with soap and water, especially after coughing, sneezing, or being in public, is highly effective. If you don’t have access to soap and water, use hand sanitiser with at least 60% alcohol.

Cover your mouth and nose with a tissue or your elbow when coughing or sneezing, and dispose of tissues straight away. Clean frequently touched surfaces such as door handles, phones, and shared equipment regularly.

In crowded or poorly ventilated spaces, wearing a mask can help protect both you and others—especially during peak cold and flu season or COVID-19 waves.

These habits are small actions that make a big impact.

Protect Those Most at Risk

If you’re feeling unwell, one of the most important things you can do is stay home—especially if you live with or care for someone vulnerable. Older adults, people with weakened immune systems, and those with chronic illnesses are more likely to become seriously ill from the flu or COVID-19.

Avoid visiting high-risk settings like aged care facilities or hospitals when you're experiencing symptoms. Let others know you’re unwell and avoid close contact until you're feeling better and no longer contagious.

These steps aren’t just about protecting yourself—they help prevent the spread of illness to those who may not be able to fight it off easily. It’s a simple way to support your community and show care for those around you.

Treatment Options for the Flu, Cold & COVID-19

Treating the Flu

Most flu cases can be treated at home with rest, fluids, and over-the-counter medications to reduce fever, relieve pain, and ease symptoms. Getting plenty of sleep and staying well-hydrated helps your immune system fight the virus.

For some people, especially those at higher risk, like the elderly, pregnant individuals, or people with chronic conditions, a doctor may prescribe antiviral medications. These are most effective when taken within the first 48 hours of symptoms and can help shorten the duration of illness or reduce complications.

It's important to monitor your symptoms and seek medical advice if you experience difficulty breathing, chest pain, or symptoms that worsen instead of improve.

Treating a Cold

The common cold is a mild, self-limiting illness that typically improves within a week and resolves on its own. Antibiotics are not effective, as colds are caused by viruses. Most people can manage a cold at home with rest, plenty of fluids, and over-the-counter medications to ease symptoms like a sore throat, congestion, and headache.

Drinking warm fluids, using saline nasal sprays, and inhaling steam may help relieve a blocked nose. Paracetamol or ibuprofen can reduce discomfort and fever if needed.

Medical treatment is rarely required for a cold, but if symptoms worsen or persist beyond 1 week, it's a good idea to consult your GP to rule out other causes.

Treating COVID-19

Most people with mild COVID-19 who have been vaccinated can recover safely at home. Recommended care includes rest, staying hydrated, and using over-the-counter medications to manage symptoms such as fever, aches, or headaches.

If you test positive, it’s important to isolate and monitor symptoms closely. High-risk individuals such as older adults or people with underlying conditions may be eligible for antiviral medications. These should be taken early, ideally within five days of symptom onset. A GP can advise if treatment is appropriate for your situation.

Seek immediate medical help if you have trouble breathing, chest pain, or if symptoms worsen quickly.

Could It Be Something Else?

Other conditions can mimic the symptoms of the cold, influenza and COVID-19 Examples include:

• Allergies: Recurrent symptoms like sneezing and itchy eyes without fever.

• Bacterial infections
  
  

If you're unsure about your symptoms, it's best to consult a GP for proper evaluation and guidance.

When to Test or See a GP

It’s not always easy to tell what’s causing your symptoms, especially when colds, flu, and COVID-19 can feel quite similar. If you're unsure, a test can help confirm whether it’s flu or COVID-19—especially if you’re at risk of complications or in contact with vulnerable people.

You should consider testing or speaking with your GP if:

• You've had recent exposure to someone with COVID-19 or flu

• You're experiencing more severe or unusual symptoms

• You’re pregnant, over 65, or have an existing health condition

• You care for or live with elderly or immunocompromised people

• You work in healthcare, childcare, or aged care

Early advice can help you access treatment quickly and avoid spreading illness to others.

Learn more about flu vaccines for older Australians.

FAQs About Cold, Flu and COVID-19

Can I get the flu and COVID-19 at the same time?

Yes, it is possible to be infected with both the flu and COVID-19 at the same time. This is sometimes called a "co-infection" and can increase the risk of severe illness, especially for older adults or those with existing health conditions.

Both viruses spread in similar ways through droplets from coughing, sneezing, or touching contaminated surfaces and can circulate at the same time, particularly in winter.

The best way to reduce your risk is to stay up to date with both your flu and COVID-19 vaccinations. Practising good hygiene and staying home when unwell also helps protect others.

Should I still get vaccinated if I’ve already had COVID or the flu?

Yes. Even if you’ve recently recovered from COVID-19 or the flu, it’s still important to stay up to date with your vaccinations. Immunity from natural infection can wane over time, and vaccination helps boost long-term protection, especially against newer variants or strains.

The flu virus changes each year, which is why the vaccine is updated annually. Similarly, COVID-19 booster doses are recommended for certain groups to maintain strong immunity.

Vaccination not only protects you from becoming seriously ill but also helps reduce the risk of spreading the virus to vulnerable people in your community.