Cold, flu, and COVID-19: What’s the difference?

In this blog, we’ll take a look at the symptoms, treatments, and prevention of the three most common respiratory infectious diseases, including key differences, and when to seek medical attention.

What is the common cold?

The common cold is a mild viral infection of the nose and throat and upper airways. It can be caused by over 200 varieties of viruses, most commonly rhinoviruses and coronaviruses¹.

Symptoms: A runny or stuffy nose, sneezing, sore throat, cough, and mild fatigue².

Prevention: To prevent catching the common cold, the WA Department of Health recommends practicing good hygiene by washing hands and using hand sanitiser, staying at home when sick, regularly cleaning high-touch surfaces (such as phones) and covering coughs and sneezes with your inner elbow or disposable tissues³.

Treatment: A study published in the Canadian Medication Association Journal found the most effective traditional treatments for the common cold to be paracetamol and ibuprofen, and the most effective non-traditional treatments to be oral zinc supplements for adults and honey at bedtime for children one year and older⁴.

What is the flu?

Influenza, commonly known as the flu, is a viral infection affecting your nose, throat and sometimes lungs. The flu is primarily caused by type A and type B influenza viruses. Type C influenza is rarer and can cause symptoms similar to the common cold in children⁵.

Symptoms: Flu symptoms tend to be more severe than those of a cold and can include sudden onset of fever, chills, muscle aches, fatigue, cough, sore throat, headache, nasal congestion, diarrhoea and loss of appetite⁵. The flu can lead to complications such as pneumonia and sepsis, especially in vulnerable populations like the elderly, young children, and those with weakened immune systems⁶.

Prevention: Just like the common cold, regularly washing your hands, and use of hand sanitiser can help to prevent the spread of the flu⁵. In addition to practicing good hygiene, the best way to prevent influenza is to get vaccinated annually⁶.

Treatment: Treating the flu primarily involves managing symptoms at home, as most cases resolve within seven to 10 days. Rest, hydration, and maintaining warmth are key, as are eating a balanced diet and avoiding exposure to cigarette smoke. Over-the-counter cold and flu medications, paracetamol, and ibuprofen can help to alleviate pain and fever⁵.

What is COVID-19?

COVID-19, caused by the novel coronavirus SARS-CoV-2, emerged in late 2019 and has since become a global pandemic.

Symptoms: Common symptoms of COVID-19 include fever or chills, cough, fatigue, muscle or body aches, headache, new loss of taste or smell, sore throat, and congestion or runny nose. Less common systems can include nausea or vomiting, diarrhea, and shortness of breath or difficulty breathing⁷.

Prevention: Just like the common cold and flu, practicing good hygiene by regularly washing your hands and using hand sanitiser, plus wearing face masks and physical distancing can help to prevent the spread of COVID-19⁸. The best way to prevent COVID-19 is, however, to get vaccinated⁹. COVID-19 vaccination is recommended for people aged 18 years or older and has been proven both safe and effective at preventing severe illness from COVID-19⁹.

For more information on the recommendations for people eligible for the COVID-19 vaccination, including boosters, visit the Australian Government Department of Health and Aged Care website.

Treatment: For mild COVID-19 cases, treatment is similar to managing the flu. Get plenty rest, take pain relievers like paracetamol and ibuprofen, stay hydrated, and use cough medicine if necessary. If you’re at a higher risk of severe COVID-19, antiviral medications may be available¹⁰. For more information, consult your GP.

Key differences between the common cold, flu, and COVID-19

Symptom severity: While cold, flu, and COVID-19 can all cause respiratory symptoms like cough and congestion, COVID-19 tends to cause more severe symptoms overall, especially in terms of respiratory distress¹¹.

Fever: While fever is rare in adults with a cold, it's a common symptom of both the flu and COVID-19⁷.

Onset and duration: Cold symptoms usually develop gradually and are milder compared to the flu and COVID-19¹. Flu symptoms tend to come on suddenly and are more intense⁵. COVID-19 symptoms can develop gradually or suddenly and may persist for an extended period, especially in severe cases⁷.

Complications: While complications can arise from all three illnesses, the flu and COVID-19 have a higher likelihood of causing severe complications such as pneumonia, particularly in vulnerable populations¹⁰.

As symptoms of the flu and COVID-19 can be incredibly similar, the only way to conclusively make a diagnosis is through a PCR test which can be performed by your local GP.

When to seek medical attention

If you're experiencing symptoms of a cold, the flu, or COVID-19, it's essential to monitor your condition closely. While most cases of these illnesses can be managed at home with rest, hydration, and over-the-counter medications^3,5,10, there are situations where medical attention is necessary.

This can include when experiencing symptoms such as^5,10:

• Difficulty breathing or shortness of breath
• Chest pain or pressure
• Confusion or difficulty waking up
• Bluish lips or face
• High fever that doesn't respond to medication
• Not passing urine
• Unconscious, faint or drowsy
• Vomiting frequently or are unable to drink fluids
• Develop a rash with fever
• Experience neck stiffness
• Have an intense headache
• Worsening symptoms over time

If you develop symptoms such as severe shortness of breath or chest pain, call triple zero (000) immediately.

While cold, flu, and COVID-19 share similarities, understanding the key differences is crucial for proper management of symptoms.

By knowing when to seek medical attention and taking appropriate preventive measures, such as hand hygiene, wearing masks, and getting vaccinated, we can all play a role in reducing the spread of respiratory illnesses and protect the most vulnerable in our community.