Flu

Also known as: Influenza A and Influenza B

Definition

The flu is an infection of the nose, throat, and lungs. It spreads easily.

This article discusses influenza types A and B. Another type of the flu is the swine flu (H1N1).

Causes, incidence, and risk factors

The flu is caused by an influenza virus.

Most people get 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 are different. But, you might have some of the same symptoms. Most people get a cold several times each year. Usually, a person gets the flu once every few years.

Sometimes, you can get a virus that makes you throw up or have diarrhea. Some people call this the "stomach flu." But, that is misleading. It is not a flu. The flu mostly affects your nose, throat, and lungs.

Which are common ways to catch the flu?The correct answer is B and C. The best lifestyle change you can make to help prevent the flu is to wash your hands often.Which of the following helps protect you from the flu?The correct answer is all of the above. Washing your hands often helps stop the spread of germs. Eating a healthy diet and getting enough sleep help boost your immune system so you’re less likely to get sick.Which of the following is NOT a symptom of the flu:The correct answer is diarrhea. The flu causes symptoms in the nose, throat, and lungs. If you are experiencing flu symptoms, you should avoid contact with other people.How long do flu symptoms last?The correct answer is longer than 1 week. Fever and aches begin to go away between 2 and 4 days after getting the flu. Sneezing, dry cough, runny nose, and sore throat may continue for several days. You may feel tired for weeks. Get plenty of rest and drink a lot of fluids while you’re recovering from the flu.Which of the following is NOT a treatment for the flu?The correct answer is antibiotics. Antibiotics kill bacteria. They do not help fight viruses, and the flu is caused by a virus. Taking antibiotics when they are not needed increases your risk of getting an infection later that can't be treated with antibiotics. Don't ask your doctor for antibiotics when you have the flu.How can you prevent spreading the flu when you’re sick?The correct answer is all of the above. If you get the flu, do all you can to prevent the virus from spreading to friends, loved ones, and strangers.You can get vaccinated for the flu with a nasal spray.The correct answer is true. There are two types of flu vaccines: a flu shot and a nasal spray. The nasal spray is called FluMist. It uses a live, weakened virus instead of a dead one. If you are 2 to 49 years old, and are not pregnant, you may use this vaccine. Talk to your doctor about whether FluMist is right for you.When is the best time to get the flu vaccine?The correct answer is in October. The CDC recommends everyone 6 months and older receive the flu vaccine. You should get the vaccine at the start of flu season (around October in the U.S.). Getting the vaccine as late as March may still help.Which of the following are side effects of the flu vaccine?The correct answer is both A and B. Most people have no side effects from the flu shot. Others may notice soreness at the injection site, minor aches, and low-grade fever for a few days after the shot. Talk to your doctor if you have concerns about getting a flu shot.Who should NOT receive a flu vaccine?The correct answer is people who are sick and have a fever. If you have a fever or other illness, you should talk to your doctor before getting vaccinated. The CDC and most doctors recommend waiting until you are healthy to get the vaccine.Washing your hands thoroughly is the best lifestyle change you can make to help prevent the flu.The correct answer is true. Washing your hands often and carefully is the best lifestyle change you can make to help prevent the flu. You should wash your hands with soap and warm water for 15 to 20 seconds, about the time it takes to sing the Happy Birthday song twice.

Symptoms

Flu symptoms usually start quickly. You can start to feel sick about 1 - 7 days after you are around the virus. Usually, symptoms start in 2-3 days.

The flu spreads easily. It can affect a large group of people in a very short amount of time. For example, students and workers get 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
  • Chills
  • Dizziness
  • Flushed face
  • Headache
  • Lack of energy
  • Nausea and vomiting

The fever and aches and pains begin to go away on days 2-4. But new symptoms occur, including:

  • Dry cough
  • Increased breathing symptoms
  • Runny nose (clear and watery)
  • Sneezing
  • Sore throat

Most symptoms usually go away in 4 - 7 days. But the cough and feeling tired may last for weeks. Sometimes, the fever comes back.

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 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 flu.

If you are very sick with the flu, you may want to see your doctor or nurse. 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 about your symptoms. No further testing is needed.

There is a test to detect the flu. It is done by swabbing the nose or throat. Most of the time, test results are available very fast. The test can help your health care provider decide the best treatment.

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 feel better when the temperature drops by 1 degree.

Over-the-counter cold medicines may make some of your symptoms better. Cough drops or throat sprays will help with your sore throat.

You will need a lot of rest. Drink plenty of liquids. Do not smoke or drink alcohol.

WHAT ABOUT ANTIVIRAL DRUGS?

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 with the flu. You may need these medicines if you are more likely to have flu complications.

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.

Expectations (prognosis)

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 in the U.S. 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

Complications

Complications may include:

Calling your health care provider

Call your doctor or nurse if you get the flu and think you are at risk for having complications.

Also call your doctor or nurse if your flu symptoms are very bad and self treatment is not working.

Prevention

You can take steps to avoid catching or spreading the flu. The best step is to get a flu vaccine.

If you have 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.
  • Use hand sanitizer often during the day and always after touching your face.
  • Cover your cough with a tissue and throw away after use.
  • 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.

References

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.

Hayden FG. Influenza. In: Goldman L, Schafer AI, eds. Cecil Medicine. 24th ed. Philadelphia, PA: Saunders Elsevier; 2011:chap 372.

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.

Review date:
April 11, 2012
Reviewed by:
David C. Dugdale, III, MD, Professor of Medicine, Division of General Medicine, Department of Medicine, University of Washington School of Medicine. Also reviewed by A.D.A.M. Health Solutions, Ebix, Inc., Editorial Team: David Zieve, MD, MHA, David R. Eltz, and Stephanie Slon.
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