Influenza (commonly called the “flu”) is a contagious respiratory illness caused by influenza viruses. The information below describes common flu symptoms, how to protect yourself and those close to you from getting the flu, and what to do if you get sick with flu-like symptoms.
People May Have Different Reactions to the Flu
The flu can cause mild to severe illness and at times can lead to death. Although most healthy people recover from the flu without complications, some people, such as older people, young children, and people with certain health conditions, are at high risk for serious complications from the flu.
Be Aware of Common Flu Symptoms
Influenza usually starts suddenly and may include the following symptoms:
- Fever (usually high)
- Tiredness (can be extreme)
- Sore throat
- Runny or stuffy nose
- Body aches
- Diarrhea and vomiting (more common among children than adults)
Having these symptoms does not always mean that you have the flu. Many different illnesses, including the common cold, can have similar symptoms.
Know the Risks from the Flu
In some people, the flu can cause serious complications, including bacterial pneumonia, dehydration, and worsening of chronic medical conditions, such as congestive heart failure, asthma, or diabetes. Children and adults may develop sinus problems and ear infections.
Know How the Flu Spreads
The flu usually spreads from person to person in respiratory droplets when people who are infected cough or sneeze. People occasionally may become infected by touching something with influenza virus on it and then touching their mouth, nose, or eyes.
Healthy adults may be able to infect others 1 day before getting symptoms and up to 5 days after getting sick. Therefore, it is possible to give someone the flu before you know you are sick as well as while you are sick.
Protection against the Flu
The single best way to protect yourself and others against influenza is to get a flu vaccination each year. Two kinds of flu vaccine are typically available:
The "flu shot" —an inactivated vaccine (containing killed virus) that is given with a needle, usually in the arm. The flu shot is approved for use in people older than 6 months, including healthy people and people with chronic medical conditions.
The nasal-spray flu vaccine —a vaccine made with live, weakened flu viruses that do not cause the flu (sometimes called LAIV for “live attenuated influenza vaccine”). LAIV is approved for use in healthy people 5 years to 49 years of age who are not pregnant. October or November is the best time to get vaccinated, but you can still get vaccinated in December and later. Flu season can begin as early as October and last as late as springtime.
The following additional measures can help protect against the flu.
Habits for Good Health
These steps may help prevent the spread of respiratory illnesses such as the flu:
- Cover your nose and mouth with a tissue when you cough or sneeze—throw the tissue away after you use it.
- Wash your hands often with soap and water, especially after you cough or sneeze. If you are not near water, use an alcohol-based hand cleaner
- Avoid close contact with people who are sick. When you are sick, keep your distance from others to protect them from getting sick too.
- If you get the flu, stay home from work, school, and social gatherings. In this way you will help prevent others from catching your illness.
- Try not to touch your eyes, nose, or mouth. Germs often spread this way.
Three antiviral drugs (amantadine, rimantadine, and oseltamivir) are approved for use in preventing the flu. These are prescription medications, and a doctor should be consulted before they are used.
What to Do If You Get Sick
Diagnosing the Flu
It is very difficult to distinguish the flu from other infections on the basis of symptoms alone. A doctor's exam may be needed to tell whether you have developed the flu or a complication of the flu. There are tests that can determine if you have the flu as long you are tested within the first 2 or 3 days of illness.
If you develop flu-like symptoms and are concerned about your illness, especially if are at high risk for complications of the flu, you should consult your health-care provider. Those at high risk for complications include people 65 years or older, people with chronic medical conditions, pregnant women, and young children.
Your doctor may recommend use of an antiviral medication to help treat the flu. These are prescription medications, and a doctor should be consulted before the drugs are used. Antiviral treatment lasts for 5 days and must be started within 2 days of illness. Therefore, if you get flu-like symptoms, seek medical care early.
Other Ways to Respond to the Flu
If you get the flu, get plenty of rest, drink a lot of liquids, and avoid using alcohol and tobacco. Also, you can take medications such as acetaminophen (e.g., Tylenol®) to relieve the fever and muscle aches associated with the flu. Never give aspirin to children or teenagers who have flu-like symptoms, particularly fever.