From what it is to how it spreads and more, get expert answers to your top flu questions.

Healthcare experts and the Centers for Disease Control and Prevention (CDC) widely agree that getting vaccinated every year is the best way to avoid unwelcome influenza viruses. But besides understanding where to go for flu shots and care, what else should you know about the flu (especially during these colder and more germy months of the year)?

Fight off common flu misconceptions, germs, and doubts with these answers to your top questions.

What is the flu?

Influenza (or the flu) is a contagious respiratory infection. Usually caused by the two main types of influenza viruses, types A and B, the flu can infect the nose, throat, and sometimes the lungs.

What are the symptoms?

Flu symptoms can range from mild to major. People infected with the flu will usually experience symptoms that come on quickly and without warning. While the signs of flu vary for different patients and populations, it’s common to experience some or all of the following symptoms:

• Fever (though not always)
• Cough
• Muscle or body aches
• Fatigue
• Headaches
• Runny nose or congestion
• Sore throat
• Vomiting or diarrhea (more common for children)

How does it spread?

The most common way flu viruses spread is when an infected person coughs, sneezes, or speaks – allowing tiny droplets to enter the mouths or noses of people nearby or to be inhaled into their lungs. Though you can also get the flu by touching contaminated surfaces and then touching your mouth, nose or eyes.

Is it dangerous?

For the most part, healthy children and adults will recover from the flu within a week. However, elderly individuals, babies and very young children, pregnant women, and people with poor immune systems or chronic illnesses are considered “high-risk” groups. For people in these groups, the flu can lead to pneumonia, bronchitis, sinus infections and, rarely, hospitalization or even death. If you are in one of these “high-risk” groups, see below for what you should do if you show signs of the flu.

How do I know if I have the flu?

If you are exhibiting some or all of the symptoms listed above, it is quite possible that you have the flu. However, since other viruses can also cause flu-like symptoms, it’s impossible to know with absolute certainty whether you have the flu based on symptoms alone. If you are at high risk for flu complications or are experiencing severe, prolonged symptoms, your doctor may be able to help determine if you have the flu with rapid influenza diagnostic tests (RIDTs), rapid molecular assays, or more specialized lab tests. Because the majority of people recover from the flu on their own within a week, these tests are not usually required.

How can I protect myself from the flu?

First of all, get your flu shot. Not only are flu vaccinations shown to protect against common influenza viruses; they can also prevent serious complications and reduce flu symptoms if you do get infected.

In addition to maintaining healthy habits like washing your hands regularly, drinking plenty of water, eating a healthy diet, and staying active, try to steer clear of people with flu symptoms whenever possible. It’s also important to avoid touching your eyes, nose, and mouth throughout the day. And you can clean or disinfect contaminated surfaces and objects to get rid of pesky flu germs.

What should I do if I have the flu?

If you have flu symptoms or a confirmed case of influenza, keep away from others as much as possible to avoid spreading your illness. According to the CDC, you should stay home (except for any necessary visits to the doctor) for at least 24 hours after your fever is gone – without the help of fever-reducing meds. And of course, cover your nose and mouth when you cough or sneeze, while continuing to wash your hands on a regular basis.

If you think you have the flu and are in one of the “high-risk” groups discussed above – or if you have severe symptoms – visit your doctor right away. He or she may prescribe antiviral medications to help alleviate your symptoms and prevent harmful complications.

Is the flu different from the stomach flu?

Yes, the flu and the stomach flu are two different things. The stomach flu occurs when the stomach and intestines become inflamed and irritated. The most common cause of the stomach flu is norovirus – which infects 19 to 21 million people each year.

The flu, on the other hand, is caused by influenza viruses and primarily affects the respiratory system.

Is the flu different from a bad cold?

Yes. The flu and common colds are both respiratory illnesses, but they are brought on by different viruses. A cold may mimic some of the symptoms of the flu, but will generally be less intense and prolonged than a true case of influenza. 

How many people get the flu each year?

According to the CDC, roughly eight percent of the U.S. population comes down with the flu every year. This percentage ranges from three percent to 11 percent based on the season.