Difference between cold, flu and covid

Overview

Cold, flu, and COVID-19 frequently share similar symptoms, particularly during the winter months. Understanding the key differences helps determine the right management plan, identify when to isolate, and know when it’s time to see a GP. Early recognition also helps protect people around you. Note: The content of this blog is for informational purposes only and does not replace professional medical diagnosis, advice, or treatment.

Cold vs flu vs COVID

Here is a quick comparison of how these illnesses differ.

Illness	Cause	Symptom onset	Severity
Cold	Rhinoviruses and other common viruses	Gradual	Mild
Flu	Influenza A or B	Sudden	Moderate to severe
COVID-19	SARS-CoV-2	Gradual or sudden	Mild to severe

Symptoms: Key differences

While symptoms overlap, each illness has a recognisable pattern. Common cold: A common cold often develops slowly and affects the nose and throat. Symptoms include:

• Runny or blocked nose
• Sore throat
• Sneezing
• Mild cough
• Low-grade fever (not always)

Flu: The flu typically starts abruptly and can cause individuals to feel very unwell. Symptoms include:

• High fever
• Sudden onset of symptoms
• Body aches
• Fatigue
• Dry cough
• Chills and sweats

COVID-19: COVID-19 symptoms can range from mild to severe and may differ between individuals:

• Fever
• Cough
• Fatigue
• Loss of taste or smell
• Sore throat
• Headache
• Chest tightness or breathing issues in some cases

Symptom comparison

This table provides a quick overview of the most common symptoms.

Symptom	Cold	Flu	COVID-19
Fever	Rare or mild	Common, often high	Common
Body aches	Mild	Severe	Sometimes
Cough	Mild	Common	Common
Sore throat	Common	Sometimes	Common
Loss of taste or smell	Rare	Rare	Common
Runny nose	Very common	Sometimes	Sometimes
Fatigue	Mild	Severe	Common

How each spreads

All three illnesses spread primarily through close contact. They can spread via:

• Respiratory droplets from coughing or sneezing
• Close contact with infected individuals
• Touching contaminated surfaces (less common now for COVID)

In Australia, transmission is higher during winter, school terms, and large indoor events.

Testing: When do you need a COVID or flu test?

Testing helps confirm the cause of symptoms and guide isolation and treatment. You may need testing if:

• You have a fever and a cough
• You’ve been in contact with a known COVID-19 or flu case
• Symptoms last more than three days
• You're at higher risk (asthma, diabetes, chronic illness)

In Australia, rapid antigen tests (RATs) are commonly used for COVID-19, while PCR tests are available through testing clinics or GPs. Flu testing is usually done with PCR if needed.

Management differences

Treatment varies depending on the illness and the severity of the symptoms. Cold management: Colds often resolve on their own with simple care.

• Rest and fluids
• Over-the-counter pain relief and decongestants

Flu treatment: Flu can be more severe, especially for older Australians.

• Rest and hydration
• Antiviral medication for high-risk groups (GP-prescribed)

COVID-19 treatment: COVID-19 management focuses on preventing spread and protecting people at higher risk.

• RAT or PCR testing
• Isolation if positive
• Antiviral medications for eligible high-risk Australians
• Rest and symptom relief

When to seek urgent care

Seek GP or urgent care if you experience:

• Difficulty breathing or shortness of breath
• Persistent high fever
• Severe chest pain
• Symptoms lasting more than 7–10 days
• Signs of dehydration
• Severe fatigue

If you experience difficulty breathing, severe chest pain, or sudden confusion, call 000 immediately or present to the nearest Emergency Department.

Prevention tips

Simple habits can significantly reduce the risk of contracting or spreading viruses.

• Wash your hands regularly
• Stay home when unwell
• Keep up to date with flu and COVID vaccines
• Eat a balanced diet and maintain hydration
• Exercise regularly
• Avoid smoking
• Wear a mask if unwell

Special section for parents

Children are more likely to catch viral infections during school terms and while attending childcare. Parents should:

• Keep children home if they have a fever, vomiting, or are unusually tired.
• Watch symptoms closely during the first few days.
• See a GP if symptoms worsen or don’t improve.
• Comply with school and childcare illness guidelines

How Hola Health can help

Having prompt access to GP care makes managing viral illnesses easier. Hola Health GPs can help with:

• Cold, flu, and COVID symptom checks
• Clinical assessment for antiviral suitability (for eligible high-risk groups) at the sole discretion of the treating doctor
• Sick leave and medical certificates
• Advice on testing and isolation
• Care plans for high-risk patients
• Symptom management for kids

Note: Telehealth is a complementary service. If you are experiencing severe respiratory distress or require a physical chest examination to rule out complications like pneumonia, you should see a GP in person.

Conclusion

Cold, flu, and COVID-19 may feel similar, but recognising their differences can help you recover more quickly and protect those around you. Most people recover with rest and supportive care. However, knowing when to test or see a GP is important. Staying informed, vaccinated, and careful during peak season helps maintain community health.

FAQs

How quickly can symptoms appear?

Colds develop gradually, flu usually starts abruptly, and COVID-19 can be either.

Is COVID-19 still more contagious than the flu?

Yes, COVID-19 remains highly infectious, especially in crowded indoor settings.

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

Yes, co-infection is possible, though it is rare.

How long does each illness last?

Colds often last 5–7 days, flu 7–14 days, and COVID-19 can range from a few days to weeks.