Influenza

Also known as the flu

Influenza is a viral infection of your nose, throat and sometimes your lungs. It spreads quickly from person to person through touch and the air. Most people who get the flu recover within a week or two, but it can cause serious illness in some people. Vaccination is your best protection.

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Key points

  1. Influenza (flu) can sometimes be confused with the common cold, but having the flu is usually much worse than having a cold. Symptoms come on suddenly and you will normally need to rest in bed.
  2. Influenza can occasionally cause serious complications and death in young children, elderly people, pregnant women or people with long-term health conditions.
  3. Flu is very infectious and easily spread to other people. Around 1 in 4 New Zealanders are infected with influenza each year. Of these, up to 80% may have no symptoms, yet are able to pass it on to other people.
  4. Your best protection is to have a flu vaccination each year.
  5. Influenza is caused by a virus, so antibiotics do not help treat the flu. However, there are other things you can do to help relieve your symptoms.

See a doctor immediately: 

If you have:

  • a high fever that doesn’t come down, especially if you are pregnant
  • chills or severe shaking
  • difficulty breathing or chest pain
  • purple or bluish discolouration of lips, skin, fingers or toes
  • seizures or convulsions
  • signs of other serious conditions, such as meningococcal disease.

If your baby or child: 

  • is breathing fast or noisily or if they are wheezing or grunting
  • is very pale
  • is drowsy or difficult to wake
  • is severely irritable, not wanting to be held
  • is limp or unable to move
  • has dry nappies or no tears when they are crying, which means they are dehydrated
  • has signs of other serious conditions, such as meningococcal disease.

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

What causes the flu?

Influenza is caused by a virus. You can catch the flu by breathing in virus-containing droplets that have been talked, sneezed, coughed or laughed into the air by a person with the flu. You can also catch the flu by touching your mouth, nose or eyes after touching something that the infected droplets have recently landed on. The virus can survive outside the body on hard surfaces for up to a week, although will usually die within 24 hours.

The strains of virus that cause influenza constantly change, so having had the flu before does not stop you getting it again. The best way to protect against getting the flu is to have an annual flu vaccination. Each year, the formulation of the flu vaccine is reviewed and updated to keep up with changing flu viruses.

What are the symptoms of the flu?

The symptoms of the flu come on suddenly and usually mean you are too sick to work, play sport or take planned holidays.

You are likely to have a combination of symptoms including:
  • muscle or body aches
  • fever (a temperature of 38°C or higher)
  • chills
  • headache 
  • sore throat
  • cough
  • runny or stuffy nose
  • stomach upset, vomiting, diarrhoea.

Symptoms can last 1 to 2 weeks. A cough may last longer. It will probably be a few weeks before you feel like you've fully recovered.

What complications can the flu cause?

Most people who get the flu recover fully, but for some, it can cause medical complications which can lead to serious illness. These may include sinus infection, ear infection, bronchitis, pneumonia, heart failure, worsening asthma and miscarriage.

Who is at risk of complications?

People at higher risk of developing complications if they get influenza include:

  • pregnant women and women who have just given birth
  • people with an ongoing health condition (like asthma, diabetes, cancer, a heart or lung condition, and conditions that affect the nervous or immune systems)
  • very overweight people
  • people aged 65 years or over
  • very young children, especially babies under 1 year.

What is the treatment for the flu?

Self-care

The best thing you can do is rest at home until you feel better. Stay home from work or school and away from other people while you are unwell. Other things you can do are to:

  • keep hydrated to replace fluids you lose because of fever and sweating
  • drink mainly water and avoid tea, coffee and alcohol as they dry you out even more
  • sip fresh lemon juice mixed with honey and hot water or gargle salt water to soothe a sore throat or dry cough
  • inhale hot steam to clear your sinuses
  • eat only light food when you are hungry 
  • use a damp cloth to cool your forehead and limbs
  • shower or bathe regularly and keep bedding clean and dry.

Medication

Influenza is caused by a virus so antibiotics do not help.

Take paracetamol or ibuprofen to help relieve fever, body aches and headache. Ask your pharmacist about other medicines such as lozenges or gargles to ease symptoms such as sore throat, runny nose and coughs. Be aware that most medicines for flu, coughs and colds contain ingredients that are not recommended for children under 6 years. Ask your pharmacist for product advice for young children and do not give aspirin to children under 16 years.

Antiviral medicines

Antiviral medicines are available that treat the flu infection. These are:

These medicines must be taken within 48 hours of your symptoms first appearing or they are unlikely to shorten your illness. They are usually only recommended if you are at high risk of complications of your flu infection, such as pneumonia (lung infection).

Antiviral medicines do not cure flu or offer long-term protection against flu. The best protection against the flu is getting the flu vaccine every year. If you do not have an antiviral medicine you are still likely to make a full recovery. GPs are only allowed to prescribe an antiviral medicine when national surveillance schemes show there is a lot of flu in the community. An antiviral medicine is also often used if you are admitted to hospital with flu. It may also be prescribed to some people to prevent flu, eg, if you live in a residential home and there is an outbreak of flu in the home. It is also given if you are at increased risk of complications of flu and have been in close contact with a person with flu.

See your doctor

See your doctor if you have not improved after 4 days, or if you are elderly or have other long-term health conditions. Young children with flu also need to be seen by their doctor.  To avoid spreading flu virus, phone your doctor or health clinic before turning up. 

How can I prevent spreading the flu?

Get a flu vaccination

The influenza vaccination is your best protection against influenza. Each year it is made available in the autumn to cover the most common flu strains expected that winter. It is most important for young children, older adults and people who have long-term health problems to be vaccinated. However, it is worth everyone getting a flu vaccination as when enough people in the community are vaccinated, the spread of a disease slows down or stops completely. Read more about why vaccinate?

Wash your hands

  • Wash your hands often, preferably with soap and water for at least 20 seconds and dry them, or use an alcohol-based hand sanitiser.
  • Wash your hands especially before preparing food or eating, after going to the toilet and after tending to sick people.
  • Also, wash your hands after returning from the supermarket or communal areas like malls, and after coughing, sneezing or blowing your nose, wiping children’s noses, or if you have touched soiled tissues.

Practice good hygiene

  • Try not to touch your nose, mouth, ears or eyes as the flu virus can enter your body this way.
  • Clean surfaces around the house more often if someone is sick, such as door handles, phones and bathroom surfaces, as flu viruses can live on these.
  • Don’t share glasses, drink bottles or cutlery, and wash dishes thoroughly.
  • Cover your mouth and nose with a disposable tissue when you sneeze or cough, or sneeze or cough into your elbow.
  • Use disposable tissues not cloth handkerchiefs for blowing your nose.
  • Dispose of used tissues straightaway in a plastic bag or lined bin with a lid (preferably one you don’t need to touch, such as a pedal bin).

Keep your distance

  • If someone is sneezing and coughing, try to keep 1 metre or more away from them.
  • Try to avoid being in large groups of people or crowded places during flu season.
  • Prevent flu spreading by you or anyone else sick staying at home and away from visitors.
  • Try to keep other members of the household away from a sick family member, eg, have them sleep in a separate room, if possible.

Learn more

The following links provide further information about influenza. Be aware that websites from other countries may have information that differs from New Zealand recommendations.   

Top tips for keeping well this winter 
Cold or the flu?

References

  1. Flu can be anywhere Fight Flu, NZ
  2. Everything you need to know about flu The Immunisation Advisory Centre & Ministry of Health, NZ, 2018
  3. Influenza Ministry of Health, NZ, 2018
  4. Influenza (flu) NPS MedicineWise, Australia, 2018
  5. How long do bacteria and viruses live outside the body? NHS, UK, 2015

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: 06 Aug 2018