What's in this article?
Flu is a common infectious viral illness spread by coughs and sneezes. It can be very unpleasant, but you’ll usually begin to feel better within about a week.
You can catch flu short for influenza all year round, but it’s especially common in winter, which is why it’s also known as “seasonal flu”.
It’s not the same as the common cold. Flu is caused by a different group of viruses and the symptoms tend to start more suddenly, be more severe and last longer.
Some of the main symptoms of flu include:
- a high temperature (fever) of 38C (100.4F) or above
- tiredness and weakness
- a headache
- general aches and pains
- a dry, chesty cough
Cold-like symptoms such as a blocked or runny nose, sneezing, and a sore throat can also be caused by flu, but they tend to be less severe than the other symptoms you have.
Flu can make you feel so exhausted and unwell that you have to stay in bed and rest until you feel better.
What’s the difference between a cold and flu?
The common cold and flu are both contagious viral infections of the respiratory tract. Although the symptoms can be similar, flu is much worse. A cold may drag you down a bit, but the flu can make you shudder at the very thought of getting out of bed.
Congestion, sore throat, and sneezing are common with colds. Both cold and flu bring coughing, headache, and chest discomfort. With the flu, though, you are likely to run a high fever for several days and have body aches, fatigue, and weakness. Symptoms of the flu also tend to come on abruptly. Usually, complications from colds are relatively minor, but a severe case of flu can lead to a life-threatening illness such as pneumonia.
More than 100 types of cold viruses are known, and new strains of flu evolve every few years. Since both diseases are viral, antibioticscannot conquer cold or flu. Remember: Antibiotics only treat bacterial infections.
Two antiviral medications are available to treat flu. But there are no medications that specifically defeat the common cold. Antibiotics may be helpful only if there is a secondary bacterial infection.
Most people who get influenza will recover in several days to less than two weeks, but some people will develop complications as a result of the flu. A wide range of complications can be caused by influenza virus infection of the upper respiratory tract (nasal passages, throat) and lower respiratory tract (lungs). While anyone can get sick with flu and become severely ill, some people are more likely to experience severe flu illness. Young children, adults aged 65 years and older, pregnant women, and people with certain chronic medical conditions are among those groups of people who are at high risk of serious flu complications, possibly requiring hospitalization and sometimes resulting in death. For example, people with chronic lung disease are at higher risk of developing severe pneumonia.
Sinus and ear infections are examples of moderate complications from flu, while pneumonia is a serious flu complication that can result from either influenza virus infection alone or from co-infection of flu virus and bacteria. Other possible serious complications triggered by flu can include inflammation of the heart (myocarditis), brain (encephalitis) or muscle (myositis, rhabdomyolysis) tissues, and multi-organ failure (for example, respiratory and kidney failure). Flu virus infection of the respiratory tract can trigger an extreme inflammatory response in the body and can lead to sepsis, the body’s life-threatening response to infection. Flu also can make chronic medical problems worse. For example, people with asthma may experience asthma attacks while they have the flu, and people with chronic heart disease may experience a worsening of this condition triggered by flu.
Symptoms of flu
It is common to confuse flu with a bad cold. Flu and cold symptoms may include a runny/blocked nose, sore throat, and cough.
Below are some flu symptoms that are different from heavy cold symptoms:
- High temperature
- Cold sweats, shivers
- Aching joints and limbs
- Fatigue, feeling exhausted
- Gastro-intestinal symptoms, such as nausea, vomiting, and diarrhea (much more common among children than adults)
These symptoms may linger for about a week. The feeling of tiredness and gloom can continue for several weeks.
How you catch flu
The flu virus is contained in the millions of tiny droplets that come out of the nose and mouth when someone who is infected coughs or sneezes.
These droplets typically spread about one metre. They hang suspended in the air for a while before landing on surfaces, where the virus can survive for up to 24 hours.
Anyone who breathes in the droplets can catch flu. You can also catch the virus by touching the surfaces that the droplets have landed on if you pick up the virus on your hands and then touch your nose or mouth.
Everyday items at home and in public places can easily become contaminated with the flu virus, including food, door handles, remote controls, handrails, telephone handsets and computer keyboards. Therefore, it’s important to wash your hands frequently.
You can catch flu many times, because flu viruses change regularly and your body won’t have natural resistance to the new versions.
How is flu spread?
The flu virus is spread from person to person through respiratory secretions and typically sweeps through large groups of people who spend time in close contact, such as in daycare facilities, classrooms, college dormitories, military barracks, offices, and nursing homes.
Flu is spread when you inhale droplets in the air that contain the flu virus, make direct contact with respiratory secretions through sharing drinks or utensils, or handle items contaminated by an infected person. In the latter case, the flu virus on your skin can infect you when you touch or rub your eyes, nose, or mouth. That’s why frequent and thorough handwashing is a key way to limit the spread of influenza. Flu symptoms start to develop from one to four days after infection with the virus.
Treatments for flu
As flu is caused by a virus, antibiotics cannot help, unless the flu has led to another illness caused by bacteria. Some of the symptoms, such as headache and body pains may be alleviated by painkillers.
Some painkillers, such as aspirin, should not be given to children under 12.
Individuals with flu should:
- Stay at home
- Avoid contact with other people where possible
- Keep warm and rest
- Consume plenty of liquids
- Avoid alcohol
- Stop smoking
- Eat if possible
- People that live alone should tell a relative, friend, or neighbor that they have flu and make sure someone can check in on them.