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.
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.
- 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.
- 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.
- 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.
- It’s important to know when to go to the doctor if you or someone you are caring for has flu-like symptoms.
- 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?
- 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
- 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)
- 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
Pneumonia – can be life-threatening
Colds Health Navigator, NZ, 2018
Influenza Health Navigator, NZ, 2018
Antibiotic resistance Health Navigator, NZ, 2018
||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.
Most adults get around two to three colds a year, and children get even more. In terms of the flu, approximately 10–20% of New Zealanders are infected every year resulting in an average of 776 hospitalisations.
The symptoms of a cold and the flu are similar, so it’s hard to tell the difference. But the flu is usually more severe and develops more quickly than a cold.
Colds and flus can be easily passed from person to person through the air, when an infected person coughs or sneezes, and touch, when a person touches an infected surface or object like doorknobs and light switches.
So what’s the difference between colds and flus, and how long should you stay away?
Cold symptoms include a sore throat, cough, runny or stuffy nose, tiredness and headache.
Most people become contagious with cold symptoms one to two days after exposure to a cold virus. These symptoms usually peak two to four days later. The common cold usually lasts about ten days.
Read more: I've always wondered: why is the flu virus so much worse than the common cold virus?
There is nothing you can take to shorten the duration of a cold, and most people will get better without needing to see a doctor. But some over-the-counter medications can help alleviate the symptoms. These include anti-inflammatories (to reduce inflammation or swelling), analgesics (to reduce pain), antipyretics (to reduce fever) and decongestants (to relieve nasal congestion).
But be careful you follow the instructions and recommended dosage for these medications. A recent study of US adults who used paracetamol, the active ingredient in many cold and flu medicines, found 6.3% of users exceeded the maximum recommended daily dose. This mostly occurred during the cold and flu season.
For your own and others’ health, the best place for you to be when you’re sick is at home.
Natural products such as vitamin C and echinacea are sometimes recommended to prevent and treat a cold, but there is limited evidence to support their effectiveness.
Common symptoms of the flu include fever (a temperature of 38°C or higher), cough, chills, sore throat, headache, runny or stuffy nose, tiredness and muscle aches.
An infected person can spread the flu for five to seven days after becoming infected. The infectious period can begin 24 hours before the onset of symptoms. This means you can spread the flu without even knowing you’re sick.
Influenza viruses can cause mild to severe illness in people of all ages. Most people will fully recover within one to two weeks and won’t require any medical attention. Similar to a cold, people can take some over-the-counter medications and other remedies to help alleviate symptoms.
Read more: Explainer: what's new about the 2019 flu vaccines, and who should get one?
But some people can become acutely unwell with the flu. They may require antiviral medication and, in severe cases, hospitalisation. Those at high risk include pregnant women, children, the elderly, and people with certain medical conditions such as HIV/AIDS, asthma, diabetes and heart and lung diseases.
The flu virus strains that circulate usually change every year, so the best way to prevent getting the flu is to get the annual flu vaccine. The vaccine is moderately effective and recommended for adults and children over the age of six months. Some common side effects may occur, such as temporary soreness, redness and swelling at the injection site, fever, headache, muscle aches and nausea.
Wash with soap for at least 20 seconds to kill the germs.
Avoid passing it on
If you feel unwell, stay home from work or school and rest (and get plenty of fluids) until you feel better. If you’ve had a fever, stay home for at least 24 hours after the fever has broken.
When you go back to work or school, you may still be infectious, so avoid passing the virus on by:
- regularly washing your hands with soap and water for at least 20 seconds and drying them properly – if soap and water are not available, use an alcohol-based hand sanitiser
- practising good cough and sneeze etiquette: cover your mouth and nose with a tissue or your upper shirtsleeve when you cough or sneeze, and throw away used tissues immediately
- not touching your eyes, nose and mouth
- frequently cleaning the surfaces and objects you’ve touched.