A cold or the flu?

Over the shorter, colder days of winter, it's not uncommon to come down with a cold or the flu. A cold is usually a mild illness but the flu can be serious, so it’s good to know the difference.

COVID-19 pandemic

If you have any respiratory symptoms such as a cough, sore throat, shortness of breath, head cold or loss of smell, with or without fever, call your GP or Healthline's dedicated COVID-19 number 0800 358 5453 to check whether you need to be tested for COVID-19.

Key points

  1. Colds and influenza (the flu) both affect your airways and how you breathe. This means they are easily confused with one another. However, a cold is not usually serious, but the flu can be.
  2. Both colds and flus are caused by viruses. In most people, the immune system will kill the virus, so you can treat colds and most flus at home. Antibiotics won’t help as they kill bacteria.
  3. Some people, such as young children, elderly people, pregnant women and people with long-term conditions, are at risk of complications from the flu may need more treatment.
  4. It’s important to know when to go to the doctor if you or someone you are caring for has flu-like symptoms.
  5. Vaccination is your best defence against the flu. Hand washing and a healthy lifestyle are your best protection against colds.

Seek urgent medical advice if you or someone you are caring for develop any of these meningitis danger symptoms:  

  • severe headache or neck pain
  • light hurts your eyes
  • drowsy, floppy or difficult to wake
  • skin rash
  • high fever (38 to 40 degrees Celsius) that doesn’t come down (especially if you are pregnant)
  • unusual or high-pitched cry.

If you are unsure what to do phone Healthline free on 0800 611 116  or your doctor for advice.

What's the difference between a cold and the flu? 

A cold



  • Mild illness lasting 1–2 weeks
  • Some symptoms, such as a cough, may continue for a few weeks


  • Moderate to severe illness with sudden onset of symptoms lasting 7 to 10 days
  • The cough and tiredness can last for weeks after the rest of the illness is over


Early signs include:

  • a sore throat
  • sneezing
  • running nose
  • mild fever.

Even though you may feel tired or have aches, most symptoms are above the neck.

After a few days, snot usually becomes thicker and may turn a greenish or yellowish colour.

Muscle pain is uncommon.

Mild headache (congested sinuses).

Sometimes a cough.


Sudden onset of:

  • fever (usually high, 38–40 degrees Celsius)
  • shivering
  • muscle aches
  • debilitating tiredness
  • headache (may be severe).

Dry cough may become moist.

Bed rest is necessary.


Washing your hands frequently

Not coughing over other people


Influenza vaccine (free for those in high-risk groups)

Washing your hands frequently

Not coughing over other people

Possible complications

Sinus congestion

Ear infection

Possible complications


Pneumonia – can be life-threatening

Learn more

Colds Health Navigator, NZ, 2018
Influenza Health Navigator, NZ, 2018
Antibiotic resistance Health Navigator, NZ, 2018

Reviewed by

Dr Sharon Leitch is a general practitioner and clinical research training fellow in the Department of General Practice and Rural Health at the University of Otago. Her area of research is patient safety in primary care and safe medicine use.
Credits: Health Navigator Editorial Team. Reviewed By: Dr Sharon Leitch Last reviewed: 25 Feb 2016