What is influenza (flu):
Influenza (flu) is a viral infection. People often use the term "flu" to describe any kind of mild illness, such as a cold or a stomach virus, that has symptoms like the flu. But the real flu is different. Flu symptoms are usually worse than a cold and last longer. The flu usually does not cause vomiting or diarrhea in adults.
Most flu outbreaks happen in late fall and winter.
What causes the flu?
The flu is caused by influenza viruses A and B. There are different strains of the flu virus every year.
What are the symptoms?
The flu causes a fever, body aches, a headache, a dry cough, and a sore or dry throat. You will probably feel tired and less hungry than usual. The symptoms usually are the worst for the first 3 or 4 days. But it can take 1 to 2 weeks to get completely better.
It usually takes 1 to 4 days to get symptoms of the flu after you have been around someone who has the virus.
Most people get better without problems. But sometimes the flu can lead to a bacterial infection, such as an ear infection, a sinus infection, or bronchitis. In rare cases, the flu may cause a more serious problem, such as pneumonia.
Certain people are at higher risk of problems from the flu. They include young children, pregnant women, older adults, and people with long-term illnesses or with impaired immune systems that make it hard to fight infection.
The symptoms of influenza (flu) appear suddenly and often include:
- Fever of 100°F (37.8°C) to 104°F (40°C), which can reach 106°F (41°C) when symptoms first develop. Fever is usually continuous, but it may come and go. Fever may be lower in older adults than in children and younger adults. When fever is high, other symptoms usually are more severe.
- Body aches and muscle pain (often severe), commonly in the back, arms, or legs.
- Pain when you move your eyes.
- Fatigue, a general feeling of sickness (malaise), and loss of appetite.
- A dry cough, runny nose, and dry or sore throat. You may not notice these during the first few days of the illness when other symptoms are more severe. As your fever goes away, these symptoms may become more evident.
Influenza usually does not cause symptoms in the stomach or intestines, such as vomiting and diarrhea.
How is the flu diagnosed?
Your doctor will ask you about your symptoms and examine you. This usually gives the doctor enough information to find out if you have the flu, especially if many cases of a similar illness have occurred in the area and the local health department reports a flu outbreak.
In some cases, the doctor may do a blood test or take a sample of fluid from your nose or throat to find out what type of flu virus you have.
How is it treated?
Most people can treat flu symptoms at home. Home treatment includes resting, drinking plenty of fluids, and taking medicine to lower your fever.
If you think you have the flu, your doctor may be able to give you medicine that can make the symptoms milder. But you need to start taking it within 2 days of your first symptoms.
Can the flu be prevented?
You can help prevent the flu by getting the flu vaccine every year. It's best to get the vaccine as soon as it's available. You can get the vaccine as a shot or in a spray that you breathe in through your nose.
The U.S. Centers for Disease Control and Prevention recommends that everyone 6 months old and older should get a flu vaccine. The vaccine is especially important for people who are at higher risk of problems from the flu, including:
- Young children.
- Adults ages 50 and older.
- Adults and children who have long-term health problems or an impaired immune system.
- Women who will be pregnant during the flu season.
The flu vaccine is also important for health care workers and anyone who lives or works with a person who is at higher risk of problems from the flu.
The vaccine usually prevents most cases of the flu. But even if you do get the flu after you've had the vaccine, your symptoms will be milder and you'll have less chance of problems from the flu. You cannot get the flu from the flu vaccine.
If you have influenza, you can expect the illness to go away on its own in about 7 to 10 days. In the meantime, you can take steps to feel better:
- Get extra rest. Bed rest can help you feel better. It will also help you avoid spreading the virus to others.
- Drink plenty of fluids to replace those lost from fever. Fluids also ease a scratchy throat and keep nasal mucus thin. Water, soup, fruit juice, and hot tea with lemon are all good choices.
- If fever is uncomfortable, sponge your body with lukewarm water to reduce fever. Do not use cold water or ice. Lowering the fever will not make your symptoms go away faster, but it may make you more comfortable.
- To relieve body aches and headache, take acetaminophen or ibuprofen.
- To help clear a stuffy nose, breathe moist air from a hot shower or from a sink filled with hot water.
- Avoid antihistamines. They do not treat flu symptoms and may make nasal drainage thicker.
- If the skin around your nose and lips becomes sore from repeated rubbing with tissues, apply a bit of petroleum jelly to the area. Using disposable tissues that contain lotion also may help.
- Use cough drops or plain, hard candy to help ease coughing.
- Elevate your head at night with an extra pillow if coughing keeps you awake.
- Avoid smoking and breathing secondhand smoke. This is good advice anytime, but it is especially important when you have a respiratory infection like a cold or the flu.
Increase your chance of staying healthy by:
- Washing your hands often, especially during winter months when the flu is most common.
- Keeping your hands away from your nose, eyes, and mouth. Viruses are most likely to enter your body through these areas.
- Eating a healthy and balanced diet.
- Getting regular exercise.
- Not smoking. Smoking irritates the lining of your nose, sinuses, and lungs, which may make you susceptible to complications of the flu.
- Taking probiotics. One study has shown that taking probiotics helps prevent influenza symptoms and reduce antibiotic use in children
In most healthy people, influenza (flu) will go away in 5 to 7 days. The worst symptoms usually last 3 to 4 days. Home treatment to ease symptoms and prevent complications is usually all that is needed.
Antiviral medicines may help:
- Reduce the severity and duration of symptoms caused by infection with influenza A or B virus.
- Shorten the length of the illness.
- Control outbreaks of the flu in nursing homes.
- Reduce the spread of the virus to people at high risk for severe complications of the flu (high-risk groups).
- Reduce complications from the flu.
People at high risk of complications are encouraged to contact a doctor within 48 hours of their first symptoms to find out whether they need medicine to shorten the illness. They also should call a doctor to receive medicine if they have been exposed to the flu.