The Flu (Influenza)

Outline of human head and chest with head turned to side. Inside of nose, airway, and lungs are visible. Droplets with virus are being breathed in to nose and lungs.

The flu (influenza) is an infection that affects your respiratory tract. This tract is made up of your mouth, nose, and lungs, and the passages between them. Unlike a cold, the flu can make you very ill. And it can lead to pneumonia, a serious lung infection. The flu can have serious complications and even cause death.

Who is at risk for the flu?

Anyone can get the flu. But you are more likely to become infected if you:

  • Have a weakened immune system

  • Work in a healthcare setting where you may be exposed to flu germs

  • Live or work with someone who has the flu

  • Haven’t had an annual flu shot

How does the flu spread?

The flu is caused by a virus. The virus spreads through the air in droplets when someone who has the flu coughs, sneezes, laughs, or talks. You can become infected when you inhale these viruses directly. You can also become infected when you touch a surface on which the droplets have landed and then transfer the germs to your eyes, nose, or mouth. Touching used tissues, or sharing utensils, drinking glasses, or a toothbrush from an infected person can expose you to flu viruses, too.

What are the symptoms of the flu?

Flu symptoms tend to come on quickly and may last a few days to a few weeks. They include:

  • Fever usually higher than 100.4° (38°C) and chills

  • Sore throat and headache

  • Dry cough

  • Runny nose

  • Tiredness and weakness

  • Muscle aches

Who is at risk for flu complications?

For some people, the flu can be very serious. The risk for complications is greater for:

  • Children younger than age 5

  • Adults ages 65 and older

  • People with a chronic illness such as diabetes or heart, kidney, or lung disease

  • People who live in a nursing home or long-term care facility

How is the flu treated?

The flu usually gets better after 7 days or so. In some cases, your healthcare provider may prescribe an antiviral medicine. This may help you get well a little sooner. For the medicine to help, you need to take it as soon as possible (ideally within 48 hours) after your symptoms start. If you develop pneumonia or other serious illness, you may need to stay in the hospital.

Easing flu symptoms

  • Drink lots of fluids such as water, juice, and warm soup. A good rule is to drink enough so that you urinate your normal amount.

  • Get plenty of rest.

  • Ask your healthcare provider what to take for fever and pain.

  • Call your provider if your fever is 100.4°F (38°C) or higher, or you become dizzy, lightheaded, or short of breath.

Taking steps to protect others

  • Wash your hands often, especially after coughing or sneezing. Or clean your hands with an alcohol-based hand cleaner containing at least 60% alcohol.

  • Cough or sneeze into a tissue. Then throw the tissue away and wash your hands. If you don’t have a tissue, cough and sneeze into your elbow.

  • Stay home until at least 24 hours after you no longer have a fever or chills. Be sure the fever isn’t being hidden by fever-reducing medicine.

  • Don’t share food, utensils, drinking glasses, or a toothbrush with others.

  • Ask your healthcare provider if others in your household should get antiviral medicine to help them preventinfection.

How can the flu be prevented?

  • One of the best ways to prevent the flu is to get a flu vaccine each year. The CDC recommends that all people 6 months of age and older get a flu vaccine every year. The virus that causes the flu changes from year to year. For that reason, healthcare providers advise getting the flu vaccine each year as soon as it's available in your area. The vaccine is usually given as a shot, which is usually the first choice of experts. Other forms like a nasal spray or needle-free vaccine are available for some people. Your healthcare provider can tell you which vaccine is right for you.

  • Wash your hands often. Frequent handwashing is a proven way to help prevent infection.

  • Carry an alcohol-based hand gel containing at least 60% alcohol. Use it when you can't use soap and water. Then wash your hands as soon as you can.

  • Try not to touch your eyes, nose, or mouth.

  • At home and work, clean phones, computer keyboards, and toys often with disinfectant wipes.

  • If possible, don't have close contact with others who have the flu or symptoms of the flu.

Handwashing tips

Handwashing is one of the best ways to prevent many common infections. If you are caring for or visiting someone with the flu, wash your hands each time you enter and leave the room. Follow these steps:

  • Use warm water and plenty of soap. Rub your hands together well.

  • Clean the whole hand, including under your nails, between your fingers, and up the wrists.

  • Wash for at least 15 seconds.

  • Rinse, letting the water run down your fingers, not up your wrists.

  • Dry your hands well. Use a paper towel to turn off the faucet and open the door.

Using alcohol-based hand cleaners

Alcohol-based hand cleaners are also a good choice. Use them when you can't use soap and water. Follow these steps:

  • Squeeze about a tablespoon of gel into the palm of one hand.

  • Rub your hands together briskly, cleaning the backs of your hands, the palms, between your fingers, and up the wrists.

  • Rub until the gel is gone and your hands are completely dry.

Preventing the flu in healthcare settings

The flu is a special concern for people in hospitals and long-term care facilities. To help prevent the spread of flu, many hospitals and nursing homes take these steps:

  • Healthcare providers wash their hands or use an alcohol-based hand cleaner before and after treating each patient.

  • People with the flu have private rooms and bathrooms or share a room with someone with the same infection.

  • People who are at high risk for the flu but don't have it are encouraged to get the flu and pneumonia vaccines.

  • All healthcare workers are encouraged or required to get flu shots.