Influenza, or flu, is a respiratory illness caused by a virus. Flu is highly contagious and is normally spread by the coughs and sneezes of an infected person. Although unpleasant, flu is rarely life-threatening.
You can also catch flu by touching an infected person, for instance, shaking hands. Adults are contagious 1-2 days before getting symptoms and up to 7 days after becoming ill. This means that you can spread the influenza virus before you even know you are infected.
In this article, we explain the symptoms of flu, how it is treated, how it differs from a cold, and the best ways to prevent flu occurring.
Fast facts on fluHere are some key points about flu. More detail and supporting information is in the main article.
Flu can be uncomfortable, but it is rarely life-threatening.
Confusing flu with a bad cold is common. Flu and cold symptoms may both include a runny/blocked nose, sore throat, and cough.
To help you tell them apart, below are some symptoms of flu that are different from a heavy cold:
There may also be gastrointestinal symptoms, such as nausea, vomiting, and diarrhea; these are much more common among children than adults.
Normally, symptoms linger for about 1 week. However, the feeling of tiredness and gloom can continue for several weeks.
It is worth noting that not every person with flu will have all of the symptoms; for instance, it is possible to have flu without fever.
Often, fatigue is one of the earliest signs of flu and cold. With flu, the fatigue is often more extreme. Other early symptoms can include cough, sore throat, fever, body ache, chills, and gastrointestinal changes.
As flu is caused by a virus, antibiotics cannot help, unless the flu has led to another illness caused by bacteria. Antivirals, such as oseltamivir (Tamiflu) and zanamivir (Relenza), may be prescribed in some circumstances.
Painkillers can alleviate some of the symptoms, such as headache and body pains.
Some painkillers, such as aspirin, should not be given to children under 12.
Individuals with flu should:
It is a good idea for people that live alone to tell a relative, friend, or neighbor that they have flu and make sure someone can check in on them.
A doctor only needs to be informed if:
If worried, a phone call to the doctor may be a better solution than making an appointment.
In the majority of cases, flu is not serious - it is just unpleasant. For some people, however, there can be severe complications. This is more likely in very young children, in the elderly, and for individuals with other longstanding illness that can undermine their immune system.
The risk of experiencing severe flu complications is higher for certain people:
Some of the complications caused by influenza may include bacterial pneumonia, dehydration, and worsening of chronic medical conditions, such as congestive heart failure, asthma, or diabetes. Children may develop sinus problems and ear infections.
Flu vaccination is the best protection against flu.
Over 200,000 people are hospitalized from flu complications each year, and about 36,000 people are estimated to die as a result of flu.
It is estimated that, globally, 250,000-500,000 people die each year as a result of flu.
In industrialized countries, the majority of deaths occur among people over the age of 65.
A flu epidemic - where a large number of people in one country are infected - can last several weeks. Health experts and government agencies throughout the world say that the single best way to protect oneself from catching flu is to get vaccinated every year.
There are two types of vaccinations, the flu shot and the nasal-spray flu vaccine. The flu shot is administered with a needle, usually in the arm - it is approved for anyone older than 6 months, including healthy people and those with chronic medical conditions.
The nasal-spray flu vaccine is a vaccine made with live, weakened flu viruses that do not cause illness.
A flu vaccine will contain three influenza viruses:
As viruses adapt and change, so do those contained within the vaccines - what is included in them is based on international surveillance and scientists' calculations about which virus types and strains will circulate in a given year.
Protection begins about 2 weeks after receiving the vaccination.
Seasonal flu vaccinations should start in September or as soon as the vaccine is on hand, and continue throughout the flu season, into January, and beyond. This is because the timing and duration of influenza seasons are never the same. Flu outbreaks usually peak at around January, but they can happen as early as October.
Certain individuals should check with their doctor before deciding to have the flu vaccine, including:
Three types of flu viruses exist - influenza A, influenza B, and influenza C. Types A and B viruses cause seasonal epidemics that hit the United States and Europe virtually every winter. The type C influenza virus causes mild respiratory illness and is not responsible for outbreaks.