Influenza (“the flu” for short) is a contagious upper respiratory (nose and throat) infection caused by the influenza virus. There are different types of flu viruses, and they can change from year to year. Flu viruses can be Type A, B, or C. Types A and B cause more severe illness, while Type C generally causes more mild flu illnesses.
Most people who get the flu get better on their own without medical treatment. However, some groups have a higher risk of medical complications. Complications could mean a stay in the hospital. Severe complications may cause death. For this reason, doctors recommend getting a flu shot every year.
Certain groups have a higher chance of having flu complications. Those groups include people who are:
- Infants and young children
- Younger than 19 years and on long-term aspirin therapy
- 65 or older
- American Indians and Alaska Natives
- Living in nursing homes or other long-term care facilities
- Living with chronic health conditions
- Living with a weakened due to a condition (like HIV) or a treatment (like chemotherapy)
Influenza symptoms include:
- Fever and/or chills
- Sore throat
- Runny or stuffy nose
- Body aches and/or a headache
- Diarrhea and vomiting (more common in children than adults)
See a doctor if you get any of the following:
- Change in a cough
- Increase in sputum (the material you cough up or blow out of your nose)
- Symptoms that get worse, rather than improving, after 3 days
- Confusion or mental fogginess that has gotten worse while you have been sick
Call 911 or go to the hospital emergency department if you have these symptoms:
- Severe trouble breathing
- Chest pain
- Loss of consciousness
Your healthcare provider may diagnose you with influenza based on your symptoms and may give you one of these tests:
- Rapid influenza diagnostic tests (RIDTs). These tests can provide results in about 10 to 15 minutes, but are not as accurate as some other tests.
- Rapid molecular assays [muh-LEK-yuh-ler AS-ey]. These tests can provide results in about 15 to 20 minutes and are more accurate than RIDTs.
- Other tests. There are highly accurate flu tests that can be performed in a hospital or special laboratory. These tests require a healthcare provider to swab the part of your throat behind your nose. Results can be provided in 1 to several hours.
Because some people may need to be treated in the hospital with antiviral medicines, you might need a lab test to diagnose the type of flu you have.
Antiviral medicines may be available as a treatment option. (Antibiotics do not work on viral infections like the flu. See your doctor right away if you are at high risk of serious flu complications. Antiviral medicines can lessen symptoms and shorten the illness by 1 to 2 days. They can also prevent serious complications, like pneumonia.
Most people with influenza get well without medical treatment by:
- Staying home and getting plenty of rest.
- Drinking plenty of fluids.
- Treating a fever with acetaminophen (Tylenol) or ibuprofen (Advil, Motrin). Follow the instructions on the package — don’t take more than the recommended dose. Do NOT give aspirin to anyone under age 18. (In children and teens, aspirin can trigger a serious illness called Reye’s syndrome.)
- Taking other medicines as directed. If your doctor has prescribed medicine, follow all directions for taking it. Take it for as long as the label tells you to, even if you start feeling better.
- Treating a stuffy nose with an over-the-counter product. Salt water or decongestant nose drops or sprays may also help. (To avoid complications, avoid using nasal sprays for more than 3 to 4 days.)
- Easing a cough by using a cold-water vaporizer.
There are several ways the flu can be prevented from spreading:
- Flu shots. Getting a flu shot each year is the best way to prevent the illness.
- Avoid close contact with sick people.
- Washing your hands before and after every meal, every time you use the bathroom, and after you blow your nose, cough, or sneeze.
- Avoid touching your eyes, nose, and mouth.
- Clean and disinfect surfaces and objects that may be contaminated with germs like the flu virus.
- Antiviral medicines. Some antiviral medicines can prevent the flu in people at a high risk of complications. These medicines may also prevent serious flu complications if you get the flu.
- If you have flu symptoms:
- Avoid going out in public or going to work for 5 to 7 days from the time your symptoms began or at least 24 hours after your fever goes away (without medicine), whichever is longer.
- Wear a surgical face mask if you need to visit a clinic or hospital (or ask for one when you get there). A face mask can help protect you and other patients.
- Cover your mouth with your elbow when you cough or sneeze. Cough into your elbow rather than your hands.