The flu is an easily spread infection of the nose, throat, and lungs.
See also: Swine flu (H1N1)
Influenza A; Influenza B
Causes, incidence, and risk factors
The flu is caused by an influenza virus.
Most people catch the flu when they breathe in tiny droplets from coughs or sneezes of someone who has the flu. You can also catch the flu if you touch something with the virus on it, and then touch your mouth, nose, or eyes.
Sometimes people confuse colds and flu. They do share some of the same symptoms. Most people get a cold several times each year. But they usually get the flu once every few years.
People call a viral illness that makes them throw up or have diarrhea the "stomach flu." This is incorrect. The flu mostly causes symptoms in the nose, throat, and lungs.
Flu symptoms usually begins quickly. Symptoms appear 1 - 7 days after you come in contact with the virus. They usually hit within 2 - 3 days.
The flu spreads easily. It often strikes a community all at once. Students or workers become sick within 2 or 3 weeks of the flu's arrival in a school or workplace.
The first symptom is a fever between 102 and 106 °F. An adult usually has a lower fever than a child.
Other common symptoms include:
- Body aches
- Flushed face
- Lack of energy
- Nausea and vomiting
Between day 2 and day 4 of the illness, the fever and aches and pains begin to go away. But new symptoms occur, including:
- Dry cough
- Increased breathing symptoms
- Runny nose (clear and watery)
- Sore throat
These symptoms (except the cough) usually go away in 4 - 7 days. Sometimes, the fever returns. The cough and feeling tired may last for weeks.
Some people may not feel like eating.
The flu can make asthma, breathing problems, and other long-term illnesses worse.
Signs and tests
Most people of do not need to see a doctor or nurse when they have flu symptoms. This is because most people are not at risk for a severe case.
People who become very sick with the flu may want to see a health care provider. People who are at high risk for flu complications may also want to see a doctor if they get the flu.
When many people in an area have flu, a doctor can make a diagnosis after hearing the symptoms. No further testing is needed.
There is a test to detect the flu. It is done by swabbing the nose and throat. The results of this test can be available rapidly. Sometimes, this test can help your health care provider decide the best treatment.
HOW DO I TREAT MY SYMPTOMS?
Acetaminophen (Tylenol) and ibuprofen (Advil, Motrin) help lower fever. Sometimes doctors suggest you use both types of medicine. Do NOT use aspirin.
A fever does not need to come all the way down to normal. Most people will feel better if their temperature drops by 1 degree.
Over-the-counter cold medicines may make some of your symptoms better. Cough drops will help with your sore throat.
You also need a lot of rest. Drink plenty of liquids. Avoid alcohol and tobacco.
WHAT ABOUT ANTIVIRAL MEDICATIONS?
Most people with milder symptoms feel better in 3 - 4 days. They do not need to see a doctor or take antiviral medications.
Doctors may give antiviral drugs to people who get very sick. People who are at high risk for problems from the flu may need these medicines.
These medicines may shorten the time you have symptoms by about 1 day. They work better if you start taking them within 2 days of your first symptoms.
Children at risk of a severe case of the flu may also need these medicines.
Millions of people in the United States get the flu each year. Most get better within a week or two.
But thousands of people with the flu develop pneumonia or a brain infection. They need to stay in the hospital. About 36,000 people die each year of problems from the flu.
Anyone at any age can have serious complications from the flu. Those at highest risk include:
- People over age 65
- Children younger than 2 years
- Women more than 3 months pregnant during the flu season
- Anyone living in a long-term care facility
- Anyone with chronic heart, lung, or kidney conditions, diabetes, or a weakened immune system
Possible complications, especially for those at high risk, include:
Calling your health care provider
Call your health care provider if you get the flu and think you are at risk for having complications. Also call your doctor if your symptoms are very bad.
You can take steps to avoid catching or spreading the flu.
Stay in your apartment, dorm room, or home for at least 24 hours after any fever is gone. Wear a mask if you leave your room.
Avoid sharing food, utensils, cups, or bottles. Cover your cough with a tissue and throw away after use. Carry hand sanitizer with you. Use it often during the day and always after touching your face.
Cough into your sleeve if a tissue is not available. Avoid touching your eyes, nose, and mouth.
The Centers for Disease Control and Prevention (CDC) recommends that everyone 6 months and older should receive the influenza vaccine.
Jefferson T, Jones M, Doshi P, Del Mar C. Neuraminidase inhibitors for preventing and treating influenza in healthy adults: systematic review and meta-analysis. BMJ. 2009 Dec 8;339:b5106.
Fiore AE, Fry A, Shay D, et al; Centers for Disease Control and Prevention (CDC). Antiviral agents for the treatment and chemoprophylaxis of influenza --- recommendations of the Advisory Committee on Immunization Practices (ACIP). MMWR Recomm Rep. 2011 Jan 21;60(1):1-24.
Last reviewed 9/16/2011 by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc., David C. Dugdale, III, MD, Professor of Medicine, Division of General Medicine, Department of Medicine, University of Washington School of Medicine.
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