Flu (Influenza)

Flu (Influenza)

What is flu?

Commonly known as influenza, ‘flu’ is a highly contagious respiratory condition caused by influenza A or B viruses. It is estimated that there are more than 100 types of known common cold viruses, and new strains of flu evolve every few years.

Often known as ‘seasonal flu’, influenza can be caught at any time of year, but occurs most frequently during winter and early spring. Flu viruses tend to be more stable in cold air. During the colder months, humidity is lower. Virus particles favour this and remain in the air. When air is more humid, virus particles pick up moisture, grow larger and tend to fall to the ground.

The virus attacks the body, spreading through the upper and / or lower respiratory tract and becomes highly contagious. Flu viruses enter the body through the mucous membranes of the nose, eyes or mouth. This makes it easy for the virus to be spread and the resulting symptoms of the infection can be very unpleasant. With plenty of rest, fluids and sufficient treatment, you’ll usually begin to feel better within a week.

What to expect

The common cold versus flu

The common cold and flu are often easily mixed up. Symptoms are similar, but there is a distinct difference. A common cold virus usually only affects the upper respiratory tract (your nose and throat). The flu virus infects the respiratory system (nose, throat, bronchial tubes, and even the lungs). Both the common cold and flu are contagious viral infections of the respiratory tract.

Symptoms commonly experienced with a cold are a congested or runny nose, a sore throat and sneezing. A little coughing (which can be dry and chesty), headaches and chest discomfort may also be experienced. Symptoms generally run their course over a period of about a week. The first 3 days are when you are at your most contagious. If your cold runs over a week, it is possible that you may have developed a bacterial infection which can easily be treated with a course of antibiotics prescribed by your doctor. Other than a bacterial infection a cold that runs past a week may also indicate an allergy or sinusitis.

The same set of symptoms apply to flu, along with a high fever which may last for several days, body aches and muscle soreness, fatigue and weakness.

Flu symptoms tend to come on more abruptly, be more severe and last longer than those of the common cold. One way to determine a common cold infection versus flu is to take your temperature. A cold rarely has symptoms of high fever above [celcius:38] or above.

Usually, complications from common cold symptoms are relatively minor. But don’t be fooled, if flu symptoms worsen and become more severe, it can lead to a life-threatening illness such as pneumonia.

Unwell little girl taking her temperature.

Types of flu

There are three types of flu viruses. The annual flu epidemic is usually caused by type A and B viruses. Type C virus also causes flu, however the symptoms are much less severe.

  • Type A Flu: This flu virus is capable of infecting both humans and animals. It is more common, however, for people to suffer the ailments associated with this type of flu. Wild birds are the most common hosts for this flu virus. Other animals known to carry the type A virus are ducks, chickens, pigs, whales, horses and seals. Type A is the flu virus that is generally responsible for large flu epidemics and is constantly changing. The A2 subtype flu virus is generally spread by people who are already infected.
  • Type B Flu: Type B viruses are only found in humans. This virus type may cause a less severe infection than type A, but can occasionally still cause more severe symptoms and infections. Type B viruses are not classified by subtype and don’t cause pandemics.
  • Type C Flu: As with type B viruses, type C is also more commonly found in people. A milder virus type than A and B, most infected with this type do not become very ill. Type C flu viruses thus do not cause epidemics.

Other types of flu viruses include:

  • Bird Flu (H5N1): Also known as avian flu, H5N1 is a viral infection spread from bird to bird. Birds can be infected by type A viruses and all its subtypes. There are three main subtypes of bird flu: H5, H7 and H9. Of the three H5 and H7 are the most severe, while H9 is less dangerous. Birds are not capable of carrying type B or C viruses, however, the main reason bird flu is cause for concern in humans is its ability to be passed from wild birds to poultry. As poultry is a commonly farmed, humans are at risk due to frequent close contact (handling the bird). The risk, however, is low in most people as the virus does not typically infect humans. People cannot catch the virus from consuming chicken or eggs. H5N1 is deadly for most birds and can be for humans and other mammals as well. Close contact with an infected bird or bird droppings has been known to infect humans with the virus, but cases where the infection has spread from human to human have been reported as extremely rare.
  • Swine Flu (H1N1): In 2009 H1N1 flu spread fairly quickly around the globe and was soon declared a pandemic by the World Health Organisation. As with other flu viruses, swine flu is highly contagious and easily caught when in close proximity to an infected person or surface they have touched, and then touching your own mouth or nose. As with bird flu, H1N1 infections are not as a direct result of consuming pork products. A person infected with H1N1 begins spreading the virus through infected droplets of saliva and bodily fluids at least a day before symptoms begin and is contagious for as many as 7 days thereafter. Children with the virus can be contagious for up to 10 days. Like seasonal flu, H1N1 can cause more serious health concerns such as pneumonia, lung infections and other respiratory problems, and for this reason is now included in the flu vaccine.
  • Stomach Flu (gastroenteritis): Stomach flu symptoms are often mistaken as the flu virus, but it is not the same. Stomach flu occurs when your stomach and intestines (gastrointestinal or GI tract) become inflamed and irritated. Causes of stomach flu range from bacteria, viruses and parasites to food reactions (particularly in dairy products) and unhygienic water. Symptoms that are similar include fever, congestion, muscle aches, headache, swollen lymph glands and fatigue. Those suffering from stomach flu will also experience abdominal cramping or pain in the stomach (or sides), nausea, vomiting and diarrhoea.

Factors to consider

Causes of Flu

Only virus types A, B and C cause the flu. Seasonal outbreaks are largely caused by type A and B. Type C is usually responsible for milder respiratory symptoms.

Risk factors and complications

You are more susceptible to getting the flu virus if you are not immunised against it. An annual flu vaccine can help keep symptoms at bay. Other ways you can also minimise your risk of contracting the flu virus include:

  • Maintaining good hygiene: washing your hands with warm water often during the day is key to keeping the flu away. Hand sanitisers, particularly during high flu season, will also help.
  • Healthy nutrition and diet: A balanced diet, along with regular exercise, plenty of rest and minimal stress are essential for a healthy immune system.

Other risk factors include:

  • Pregnancy: Changes in a woman’s immune system during pregnancy can make her more vulnerable to complications from a bout of flu. There is also an increased risk of problems affecting her pregnancy and the baby if her illness worsens, but this is easily managed with the help of a medical professional. Prevention is also often better than cure, and most flu shots are safe for expectant moms. Flu shots can generally be given during any trimester but should always be discussed with your doctor or gynaecologist before opting for them. A nasal vaccine, however, is not recommended for pregnant women.
  • Children under 2 years of age: Little ones are at higher risk for flu-related problems as their immune systems are generally weaker and fighting off new viruses and bacteria as they grow. It is reasonably normal for a youngster to get as many as 6 to 8 colds a year, as well as experience ear and sinus infections, bronchitis and croup. A baby under 6 months can’t get a flu shot, but parents, other family members and caregivers can get vaccinated themselves as a way to help protect the infant from falling ill from flu.
  • Seniors: As we age, our immune systems weaken. Falling ill with flu in the latter stages of life can really take a toll on the body. Seniors (older than 65), and especially those living in a retirement centre, are at higher risk for getting the flu, as well as experiencing further complications. Seniors with other known conditions or long-term illnesses are also at a higher risk for further complications. A high-dose vaccine is recommended for those 65 and older. A higher dose generally has about 4 times as much active ingredient as a regular flu shot which can assist in keeping an older immune system a little healthier and stronger. Pneumococcal vaccines, which can help to protect older immune systems against serious illnesses such as meningitis, pneumonia and blood infections, are also recommended for those 65 years of age and above.

Common complications associated with the flu virus include:

When to see your doctor

If you are already experiencing flu symptoms it may be necessary to see your doctor if:

  • You experience a persistently high fever lasting more than 3 days. This can be a sign of another bacterial infection, which will require treatment by a medical professional.
  • You experience pain when swallowing. A sore throat can cause mild discomfort when you’re down with the flu, but severe pain can mean that you are suffering from strep throat (a bacterial infection causing pain and inflammation), and this will require treatment recommended by your doctor.
  • You have a persistent cough that doesn’t go away after 2 to 3 weeks. Bronchitis, post nasal drip, sinusitis and even asthma may cause a persistent cough.
  • You are unable to clear nasal congestion and headaches after a week. Allergies or a blockage of sinus passages could be the cause of persistent congestion and headaches and lead to sinusitis (a sinus infection). Pain around the eyes and face with a thick nasal discharge lasting longer than a week could point to a bacterial infection which will require an antibiotic. Most sinus infections, however, won’t likely need an antibiotic to clear at all.

Emergency situations can arise in some cases. Signs of crisis include severe chest pain, severe headache, shortness of breath, dizziness, confusion and persistent vomiting. If any of these symptoms are noted in adults, it is best to get emergency medical attention straight away.

Urgent action will also need to be taken in children experiencing rapid or difficulty breathing, a bluish skin colour, dehydration (not able to take in enough fluids), lethargy and failure to interact normally, extreme distress or irritability, fever with a rash, as well as symptoms that may have shown improvement but suddenly became worse.

Diagnosing flu

As most outbreaks of flu tend to occur during the colder months of the year, it is likely that your doctor will diagnose your illness based on your symptoms, the strain of flu already known to be circulating and his / her own clinical judgement.

In some instances, your doctor may request a test in order to make a diagnosis. The most common test which may be requested is the ‘rapid influenza diagnostic test’. Your doctor will swipe the inside of your nose and back of your throat with a swab and send for testing. Results can be received in approximately 30 minutes or less and can help to determine which type of flu virus (A or B) you have been infected with. The test is also useful for ruling out any other potential concerns, such as a bacterial infection, which will require a different course of treatment.

Flu treatments

As flu is a viral infection and not a bacterial one, antibiotics are not suitable medications for treatment. If taken with the intent of treating flu-like symptoms you may increase your risk of getting a bacterial infection later on, which will be resistant to antibiotic treatment.

Antiviral medications are available to help alleviate symptoms of flu. Antibiotics will only be prescribed by your doctor if he or she diagnoses a secondary bacterial infection requiring treatment as well.

Antiviral medications assist in decreasing the severity and duration of flu symptoms, and are best taken within 48 hours of the onset of symptoms. Most antivirals available do have side effects, so it is important to consult your doctor to discuss your overall condition before taking them.

Antiviral medications are also beneficial for children to take as they can help a child recover sooner and thereby prevent any potential serious complications. Treatment can depend on the symptoms you are experiencing.

Below are some suggestions for symptoms experienced when down and out with flu:

  • For nasal or sinus congestion: A decongestant can be helpful to reduce swelling in the nasal passageways. Decongestants come in both oral or nasal spray forms. Nasal spray decongestants are not usually recommended for use for more than a 3 days as rebound symptoms can occur if use stops for a short period and is then used again. Saline sprays (instead of a medicated spray) can also provide some relief, helping to loosen thick mucus from the nasal passages but have no rebound effect. If you have high blood pressure it is strongly advisable to consult your doctor before taking a decongestant as some can elevate heart rate and cause further complications.
  • For a runny nose, postnasal drip, or itchy, watery eyes: An antihistamine will help to block the effect of ‘histamine’ and provide relief from sneezing, itching and nasal discharge. Antihistamines can often make people feel drowsy.
  • For a cough: An occasional cough can help to clear the lungs of excess phlegm and other pollutants. If a cough persists, a doctor will need to diagnose and treat specific symptoms experienced. An array of over-the-counter cough medicines are easily available for any type of cough (for instance dry or chesty). Ask your pharmacist for assistance in selecting the one most appropriate for your symptoms.
  • For fever and body aches: Over-the-counter medications (also safe for children with fever and pain symptoms) include acetaminophen, ibuprofen and naproxen. Your pharmacist will be able to assist you with selecting one that will provide the best relief for your symptoms. It is not recommended to give children aspirin to alleviate pain and fever. It has been found that aspirin is linked to a potentially fatal illness called Reye’s syndrome (a swelling in the brain, liver and other organs). Although rare, the risk is especially high in children. Paracetamol and ibuprofen are better options for treating pain and fever in children.
  • For a sore throat: Drinking plenty of fluids and using salt water gargles (1 cup of warm water and a teaspoon of salt) is helpful in alleviating the pain of a sore throat. Over-the-counter pain relievers, medicated lozenges and gargles can also help soothe a sore throat for a period of a few days when symptoms are at their worst. If pain and sensitivity persists past a few days, some medications which you may still be using can mask signs of strep throat, which will need to be treated with prescribed antibiotics.

Over-the-counter and prescribed medications are sometimes mixed with other multi-symptom cold and flu remedies, so it strongly advisable to run the combinations you intend to take by your pharmacist or doctor beforehand. You can easily overdose, experience complications or bad reactions due to specific ingredients in medications.

Home remedies include:

  • Breathing aromatic steam: fill a bathroom, sink or bowl with steamy water, drape a towel over your head and lean over the steam. Place some fresh ginger or a few drops of eucalyptus oil in the water to help clear the nasal passages and congestion.
  • Take a warm shower: steamy air helps to clear your head and chest while moistening and thinning out mucus in your sinuses.
  • Spice up your meals: Garlic is good for your immune system and may help to alleviate head congestion. Chilli peppers are a good source of capsaicin, an antioxidant that can also alleviate congestion. Horseradish is also good for clearing congestion too.


How long does flu last?

Primary symptoms of flu (fever, fatigue, body aches, chills, headaches, sore throat and cough) are usually at their worst for between 3 and 4 days.

A cough may linger a little longer, but full recovery can take between 7 and 10 days. Some people do experience a little fatigue for a few weeks once other symptoms clear up.

How long is flu contagious?

The flu virus is at its most contagious between 24 to 72 hours of becoming infected, but can be spread for up to 7 days once symptoms start. The virus can live in your mucus for 24 hours before you even begin to feel unwell.

It is best to stay home and rest at least 24 hours once your fever has broken without the use of fever-reducing medicines. Once your fever has gone for at least a day, you are no longer contagious. Young children can still spread the flu virus after 2 weeks of feeling unwell.

Can I exercise when I have the flu?

Regular exercise helps to strengthen your immune system and fight viral and bacterial infections. When you exercise, your white blood cells (the ones that help keep infections at bay) travel through your body faster and thus do their job a little quicker too.

But should you exercise when you’re feeling under the weather? When you have the flu what your body needs most is rest. Your immune system works best when it isn’t working overtime, and given that exercise temporarily suppresses the immune system, it’s best not to further weaken your body when you are ill.

Also, if you have a fever, you are likely at your most contagious, so it is better to skip the workout, especially if around other people. A high temperature pulls moisture out of your body. If you dehydrate or lose too much fluid, you could delay your recovery.

Wait it out (and rest) until at least 24 hours after your fever has broken (without the aid of medications) before you go back to your exercise routine.

What should you eat when you have the flu?

There’s an old saying, “Feed a cold, starve a fever.” Are there foods you should you be eating when you're down with the flu?

Like exercise, good nutrition is essential for your immune system, and is even more important when feeling under the weather. A well-nourished immune system helps fight a virus and what you eat will be key to how well you recover.

Foods that combat flu include:

  • Protein builds strength in the body, and is even more important when you are ill. Lean meat, poultry, fish, nuts and seeds, as well as legumes, dairy and eggs are good sources to tuck into.
  • Vitamins B6 and B12 help to keep your immune system in good working condition. Vitamin B6 comes in protein-rich foods such as potatoes, turkey, spinach and beans, as well as enriched cereal grains. Milk, meat and fish are good sources of vitamin B12, a powerful immune booster.
  • Vitamin C and folic acid can help to make you feel better faster. A good source is orange juice (especially when consumed with the pulp).
  • Minerals such as selenium and zinc are also good immune boosters. Also found in protein-rich foods such as nuts, beans, meat and poultry, these minerals will certainly help boost your immune system.
  • Flavonoids found in the soft white skin of citrus fruits (grapefruit, oranges, lemons and limes) can really boost your immune system, particularly when it’s at its lowest.
  • Antioxidants such as glutathione helps to strengthen the immune system and fight infections. Sources of this powerful antioxidant can be found in the red, pulpy area of a watermelon, in kale, broccoli, collard greens and cabbage.

Some people do find that dairy produces more mucus, as well as make any nausea or vomiting symptoms worse. You can avoid dairy altogether for a few days if you experience these symptoms and rather try and consume bland foods such as toast, rice, bananas and applesauce. You can also try sipping clear drinks to keep your fluid levels up. Chipped ice, juices, ginger ale and clear broths can help.

Warm decaffeinated tea with honey can help soothe a sore throat. If your airways are particularly congested, warm drinks are more beneficial for you than cold ones.

Warm decaffeinated tea with honey and lemon.

How effective is the flu vaccine?

The flu vaccine reduces the odds of contracting the flu virus by up to 60%. This figure does tend to vary from year to year and among different groups of people. The statistic generally applies to healthy people, and the effectiveness of a vaccine depends on a number of different factors:

  • Young woman receiving flu vaccine.Age: The vaccine is most effective in healthy adults. The vaccine is less effective in children under 24 months, who have weaker immune systems. The immune system also weakens naturally around middle age. People in this age group tend to find that the vaccine doesn’t work as well as it once did. It is important, however, for older people to get the vaccine as the virus can be more easily prone to possible complications in this age group.
  • General health: Vaccines work by spurring the immune system into action, “teaching” your body to identify a virus and “learn” how to defend against it. If you then become infected with the virus, the body can quickly recognise it and begin fighting it off. The effectiveness of the vaccine depends on how vigorously your body responds to it. A vaccine may not work as well with an immune system that is already weak or where there are chronic illnesses.
  • When you get the vaccine: It is best to get the flu vaccine before the flu season starts. The further you get into the flu season, the higher your risk of getting the flu. It takes about 2 weeks for the flu vaccine to take effect. If you are exposed to the flu virus in that period, you may still fall ill.
  • How well the current vaccine is matched with dominant flu strains: An annual flu vaccine is necessary for optimal protection as old vaccines aren’t always as effective year on year. Flu vaccines are often updated each season to protect you against dominant strains of flu for that year.

A flu vaccine unfortunately cannot guarantee that you won’t get flu, but it can help at least provide partial immunity. You may still fall ill, but your symptoms are likely to be somewhat milder.

Disclaimer - MyMed.com is for informational purposes only. It is not intended to diagnose or treat any condition or illness or act as a substitute for professional medical advice.