Flu, also known as influenza, is caused by influenza viruses that infect the respiratory tract – this includes your nose, throat, and lungs. It is highly contagious and is spread by breathing in droplets from the coughs and sneezes of an infected person.¹

Flu affects people of all ages and can sometimes cause serious illness, even in healthy people. It is a seasonal infection that most commonly circulates during the winter months.^1,2 Flu varies from year to year – sometimes flu season can cause mild infection and be short in duration. Other times, there may be a longer flu season that causes more severe illness than previous years.¹

What are flu-related symptoms?

Some flu symptoms are the same as symptoms of the common cold, but with some important differences.^3,4 The flu often comes on fast, with aches, pains, and a fever .4,5 And, unlike a cold, a flu can leave you feeling low for weeks.³

The most common symptoms of the flu include:¹

sudden high fever (38°C or more)
a dry cough
body aches (especially in the head, lower back and legs)
feeling extremely weak and tired

Other symptoms can be:¹

chills
aching behind the eyes
loss of appetite
sore throat
runny or stuffy nose.

Early signs of the flu

You may notice some early signs of the flu that indicate you’re becoming ill. Early signs of the flu can include:⁶

A sudden cough
Headache
A sudden fever
Aches or pains
Sore throat
Intense fatigue

Flu symptoms such as fever, headache and sore throat can happen pretty quickly but typically decrease after about eight days. You may find any mild chest discomfort becomes more noticeable from day 4 although any fever and muscle aches typically decrease around this time. Sometimes cough and fatigue can last for another one to two weeks.^1,4

What Causes the Flu?

Influenza, or flu, is a highly contagious illness caused by influenza viruses. Most of the virus is present in droplets from the airways, therefore it can be spread through sneezing and coughing. ³ These viruses can enter your body in a few different ways. You might inhale the virus after someone with the flu sneezes or coughs.^4,5 In addition, the virus can land on surfaces where it can survive for several hours⁷ and if you touch it and then touch your face or eyes it can enter your body that way.^4,8

The intensity of a flu outbreak depends on the virus, how well it is spread from person-to-person, and how susceptible a community is to infections. For example, the flu can be more severe in communities that don’t have much immunity to influenza, such as those with mainly unvaccinated individuals.⁴ People with high-risk medical conditions and the elderly are more likely to get seriously ill from influenza.⁴

People infected with influenza are most contagious in the first 3 to 4 days after their symptoms begin. In addition, most people may be able to infect others starting 1 day before symptoms develop and up to 5 to 7 days after becoming sick. Children, elderly adults and people with chronic illnesses may be infectious for longer.⁴

Types of Flu

Influenza viruses can be divided into three main types – A, B and C. Influenza type A and B are the most common causes of flu, and cause most of the flu outbreaks and epidemics (defined as the widespread occurrence of an infectious disease within a community at a particular time). Influenza type C typically causes sporadic, mild respiratory symptoms and can cause an illness in children that resembles the common cold.^4,10

Most people infected with the flu have influenza type A. This type of influenza virus has caused most of the worldwide epidemics.¹⁰ Influenza type A can also infect animals, and sometimes this infection can be passed from animals to humans. ¹⁰ Subtypes of influenza type A include:

Avian influenza (H5N1): Also known as ‘bird flu’ since it mainly affects birds. This virus can cause serious infection and death in humans, but the number of human cases has been low, and it hasn’t been found in Australia. It can spread from infected birds to humans, but there’s no evidence that it passes from person-to-person.¹⁰
Swine flu (H1N1): Found in pigs but can spread to humans. Infection is mild for most people but can cause serious infection in high-risk groups, such as those with chronic conditions, pregnant people and Aboriginal or Torres Strait Islander people. H1N1 caused a global pandemic in 2009, which ended in August 2010.¹⁰

Flu Treatment and Prevention

One of the best ways to avoid catching the flu is to avoid close contact with people who are currently infectious.^8,11 Unfortunately, this is not always possible to know or do, especially if you’re caring for a loved one. So here are some home remedies for flu symptoms that you can try if you or someone you know has flu symptoms:

Get plenty of rest: Your body is fighting the infection so give it the energy it needs by taking time to rest to aid your recovery.¹²
Eat a healthy diet with plenty of fruits and vegetables: Eating foods with vitamin A (meat, dairy, eggs), vitamin C (citrus fruits, leafy greens) and vitamin D (mushroom, tuna, salmon) can help to boost your immune system.12–16
Drink hot water and honey: This can help to relieve a sore throat.¹²
Take a steamy bath/shower: Steam in a closed room can help to relieve a blocked nose.¹²
Keep your distance: The best thing to do when you’re sick is to stay at home to avoid spreading the virus to other people. Additionally, if someone you know is sick with the flu, keep your distance to avoid catching the virus.^8,11
Practice good hygiene: Wash your hands often to minimise the spread of the virus.^8,11 Avoid touching your nose, mouth or eyes as the virus can easily enter your body this way.⁸ If you need to sneeze or cough, use a disposable tissue and throw it in the bin straight away.⁵
Clean surfaces regularly: Because the virus can survive on all kinds of hard surfaces, try to regularly clean frequently touched surfaces such as door handles, remote controls, banister or computer keyboards.⁸
Get the annual flu vaccination: Another way to help protect against the flu is to get an annual flu vaccination (the flu jab).¹⁷

When to See a Doctor for the Flu

If you have flu symptoms but you’re otherwise fit and healthy, there’s no need to see a doctor. However, you should see a doctor if you or your child has flu symptoms and:¹²

are younger than 5 years old
are aged 65 years or older and living in an aged care home
are pregnant
are very obese
are an Aboriginal or Torres Strait Islander person
have severe asthma, breathing problems or a lung disease
have a disease that affects your muscles and/or the nerves that control them, and that can affect your ability to breathe
have a weakened immune system
are homeless
are a smoker

These conditions may mean that you’re more likely to get seriously ill with the flu, so see your doctor if you have any of the above conditions and flu symptoms.¹²

Additionally, you should see a doctor if you or your child have flu symptoms and:¹²

can’t or won’t drink fluids
are vomiting frequently and/or are unable to drink fluids
have an intense headache
are pale and feel sleepy
have chest pain
are experiencing breathing difficulties
develop a rash with fever
are experiencing neck stiffness
find light hurts their eyes
are worried

Lemsip Products

Lemsip has a range of over-the-counter cold and flu relief products, designed specifically for the symptoms you are experiencing:

PAIN & FEVER

LEMSIP MAX COLD & FLU HOT DRINK

Pain relief action
Suitable for 12 years+

PAIN, FEVER & BLOCKED/RUNNY NOSE

LEMSIP MAX COLD & FLU WITH DECONGESTANT

Pain relief and decongestant action
Available as a hot drink in Lemon, Blackcurrant and Honey & Ginger flavours
Suitable for 12 years+

PAIN, FEVER, BLOCKED/RUNNY NOSE & CHESTY COUGH

LEMSIP ALL IN 1 MULTI-SYMPTOM RELIEF

Pain relief, decongestant and expectorant action
Available as a hot drink or capsules
Suitable for 12 years+

You can pick Lemsip products up from your local pharmacy or supermarket. They have different active ingredients and different formulations. If you are unsure which formulation is right for you, talk to your pharmacist.

Always read the label and follow the directions for use. Incorrect use could be harmful. RKT-M-01558.

[Disclaimer]

This article is for general information only and not intended as a substitute for medical advice. All information presented on these web pages is not meant to diagnose or prescribe. In all health-related matters, always consult your healthcare professional.

References

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Health Navigator New Zealand. Influenza vaccine for adults. Updated September 2022. https://www.healthnavigator.org.nz/medicines/i/influenza-vaccine-adults/. Accessed October 25, 2022.
Eccles R. 2009 Mechanisms of symptoms of common cold and flu. In: Eccles R., Weber O. (eds) Common Cold. Birkhäuser Advances in Infectious Diseases (BAID). Birkhäuser Basel
Moghadami M. A narrative review of influenza: A seasonal and pandemic disease. Iran J Med Sci 2017;42(1):2–13
Uyeki TM. In the Clinic: Influenza. Ann Intern Med 2017;167(5):ITC33-ITC48.
Queensland Health. What’s the difference between a cold and the flu? Available at: https://www.health.qld.gov.au/news-events/news/difference-between-cold-flu-virus (accessed July 2020).
Greatorex JS, et al. Survival of influenza A(H1N1) on materials found in households: Implications for infection control. PLoS One 2011;6(11):e27932
Barker J, et al. Spread and prevention of some common viral infections in community facilities and domestic homes. J Appl Microbiol 2001;91(1):7-21.
Centers for Disease Control and Prevention [Internet]. How Flu Spreads. Updated August 2018. https://www.cdc.gov/flu/about/disease/spread.htm
HealthDirect. Influenza A. Available at: https://www.healthdirect.gov.au/influenza-a-flu. Accessed September 08, 2022.
Jacobs SE, et al. Human rhinoviruses. Clin Microbiol Rev 2013;26(1):135-62.
HealthDirect. Influenza . Available at: https://www.healthdirect.gov.au/flu. Accessed September 08, 2022.
Singh B, et al. Nutrients. 2022;14(9):1909.
HealthDirect. Vitamin A and your health. Reviewed September 2022. https://www.healthdirect.gov.au/vitamin-a-and-your-health. Accessed September 07, 2022.
HealthDirect. Vitamin C and your health. Reviewed September 2022. https://www.healthdirect.gov.au/vitamin-c-and-your-health. Accessed September 07, 2022.
HealthDirect. Vitamin D and your health. Reviewed September 2022. https://www.healthdirect.gov.au/vitamin-d-and-your-health. Accessed September 07, 2022.
Better Health Channel. Flu (influenza) – immunisation. Updated April 2019. https://www.betterhealth.vic.gov.au/health/healthyliving/flu-influenza-immunisation. Accessed August 2020.