Most people get the flu when they breathe in tiny airborne droplets from the 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.
People often confuse colds and flu. They are different, but you might have some of the same symptoms. Most people get a cold several times a year. On the contrary, people get the flu only 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." This is a misleading name because this virus is not the actual flu. The flu mostly affects your nose, throat, and lungs.
Flu symptoms will often start quickly. You can start to feel sick about 1 to 7 days after you come in contact with the virus. Most of the time symptoms appear within 2 to 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 co-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°F (38°C) and 106°F (41.1°C). An adult often has a lower fever than a child.
The fever, aches, and pains begin to go away on days 2 through 4. But new symptoms occur, including:
Increased symptoms that affect breathing
Runny nose (clear and watery)
Most symptoms go away in 4 to 7 days. The cough and tired feeling 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 (chronic) illnesses and conditions worse.
Exams and Tests
Most people do not need to see a health care provider when they have flu symptoms. This is because most people are not at risk for a severe case of the flu.
If you are very sick with the flu, you may want to see your provider. People who are at high risk for flu complications may also want to see a provider if they get the flu.
When many people in an area have flu, a provider 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 provider prescribe the best treatment.
Acetaminophen (Tylenol) and ibuprofen (Advil, Motrin) help lower fever. Providers sometimes suggest you to 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.
Most people with milder symptoms feel better in 3 to 4 days. They do not need to see a provider or take antiviral medicines.
Providers 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 The health problems below may increase your risk of getting sicker with the flu:
Lung disease (including asthma)
Heart conditions (except high blood pressure)
Kidney, liver, nerve, and muscle conditions
Blood disorders (including sickle cell disease)
A weakened immune system due to diseases (such as AIDS), radiation therapy, or certain medicines, including chemotherapy and corticosteroids
Other long-term medical problem
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.
Millions of people in the United States get the flu each year. Most people 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 United States 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 the age of 65
Children younger than 2 years old
Women who are more than 3 months pregnant
Anyone living in a long-term care facility
Anyone with chronic heart, lung, or kidney conditions, diabetes, or a weakened immune system
Grohskopf LA, Olsen SJ, Sokolow LZ, et al. Prevention and control of seasonal influenza with vaccines: recommendations of the Advisory Committee on Immunization Practices (ACIP) -- United States, 2014-15 influenza season. MMWR Morb Mortal Wkly Rep. 2014;63(32):691-7. PMID: 25121712 www.ncbi.nlm.nih.gov/pubmed/25121712.
Jefferson T, Jones M, Doshi P, et al. Neuraminidase inhibitors for preventing and treating influenza in healthy adults and children. Cochrane Database Syst Rev. 2014;4:CD008965. PMID: 24718923 www.ncbi.nlm.nih.gov/pubmed/24718923.
Linda J. Vorvick, MD, Medical Director and Director of Didactic Curriculum, MEDEX Northwest Division of Physician Assistant Studies, Department of Family Medicine, UW Medicine, School of Medicine, University of Washington, Seattle, WA. Also reviewed by David Zieve, MD, MHA, Isla Ogilvie, PhD, and the A.D.A.M. Editorial team.