Over the shorter, colder days of winter, it's not uncommon to come down with a cold or the flu. We also now have COVID-19 to be aware of. A cold is usually a mild illness but the flu and COVID-19 can be serious, so it’s good to know the difference.
- Colds, influenza (the flu) and COVID-19 all 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 and COVID-19 can be.
- Colds, the flu and COVID-19 are all caused by viruses. In most people, your immune system will kill the virus, so you can treat mild-to-moderate symptoms at home (or in managed isolation for COVID-19). Antibiotics won’t help as they kill bacteria.
- Some people, including young children, elderly people, pregnant women and people with long-term conditions, are at greater risk of complications and may need more treatment.
- It’s important to know when to seek medical advice if you or someone you are caring for has flu-like symptoms. If you are high-risk for COVID-19 make sure you get tested.
- Vaccination is your best defence against the flu. Hand washing and a healthy lifestyle are your best protection against colds. Learn about preventing the spread of COVID-19.
What's the difference between a cold and the flu?
See also symptoms of COVID-19.
Influenza (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 7–10 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 (flu) vaccine (free for those in high-risk groups).
Washing your hands frequently.
Not coughing over other people.
Pneumonia – can be life-threatening
Could it be COVID-19?
Symptoms of COVID-19 are similar to a range of other respiratory illnesses that are much more common, such as colds or the flu.
Symptoms of COVID-19 include:
- a cough
- a high temperature (at least 38˚C)
- shortness of breath
- a sore throat
- sneezing and runny nose
- temporary loss of smell.
These symptoms do not necessarily mean you have COVID-19. Difficulty breathing is a sign of possible pneumonia and requires immediate medical attention.
If you have cold or flu symptoms and are high-risk for COVID-19 make sure you get tested for COVID-19.
If you are unsure whether you need to be tested, call your GP or Healthline's dedicated COVID-19 number 0800 358 5453.
When to seek advice for colds or the flu
You can treat most colds and flu-like illnesses with rest and self-care at home, but you need to know when to seek medical help.
Phone your medical clinic for advice if you:
- are not getting better
- are pregnant
- have diabetes or a health condition affecting your breathing, heart or immune system
- are aged 65 or older
- have a sore throat and are Māori or Pasifika aged 3–35 years
- are concerned or not sure what to do.
If you are unsure what to do phone Healthline free on 0800 611 116 or your doctor for advice.
When to seek immediate medical help
If you have any of the following signs you may be seriously unwell and need emergency care:
- difficult or painful breathing
- bluish lips or tongue
- chest pain
- coughing up blood
- severe shaking, rigors
- confusion or difficult to wake
- stiff neck
- rash with purple or red spots or bruises
- clammy skin
- not urinating or dark coloured pee.
Phone 111 or go to the hospital emergency department right now. Do not delay.
Self-care for colds and the flu
Rest – at home if possible so you don’t spread bugs.
Drink plenty of water, warm lemon and honey drinks or soups to avoid dehydration (honey is not safe for children under one year).
Sore throat? Suck a teaspoon of honey or gargle salt water. Adults can also try a medicated lozenge, gargle or throat spray.
Blocked or runny nose? Ask your pharmacist about decongestants and nasal sprays.
Cough? Sip a lemon and honey drink or ask your pharmacist about cough lozenges or medicines that may be suitable for you.
Aches and pains? Try paracetamol OR cold and flu medicines (check doses carefully and ask your doctor or pharmacist if safe for you).
Avoid antibiotics – they can’t cure colds, flus or most coughs as these are caused by viruses.
Avoid catching and spreading bugs
Take care of your health and protect your whānau and community.
- Wash your hands for 20 seconds and dry them well.
- Cover your coughs and sneezes.
- Avoid touching your face with unclean hands.
- Don’t share personal items such as cups, food utensils or towels.
- Clean and disinfect surfaces often, like doorknobs.
- Stay home if you are sick and avoid close contact with others.
- Keep coughs away from other people.
Learn more about preventing the spread of COVID-19.
Keep well this winter
Get the flu vaccine each year – it might be free for you.
Keep your immune system strong – be active, eat healthy food, be smoke-free and get plenty of sleep.
Stay warm – heat your home to at least 18°C.
Quit smoking – smokers get more colds, symptoms are worse and they last longer.
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.