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.

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, your 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. Immunisation is your best defence against the flu, and hand washing and a healthy lifestyle is your best defence 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
  • eyes intolerant to light
  • drowsy, floppy or difficult to wake
  • skin rash
  • high fever (38 to 40 degrees Celsius) that doesn’t come down (especially if pregnant)
  • unusual or high-pitched cry.

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

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


A cold



  • Mild illness lasting 1–5 days.
  • 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 necessary.


Washing your hands frequently.

Covering your cough.

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

Washing your hands frequently.

Covering your cough.

Possible complications

Sinus congestion

Ear infection


Pneumonia – can be life-threatening

Learn more

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

Credits: Health Navigator Editorial Team. Last reviewed: 25 Feb 2016