Each year, millions of people suffer from seasonal influenza, which is often called the flu. Flu is a respiratory illness caused by viruses that infect the nose, throat, and sometimes the lungs.

Flu can be a mild illness for some people. For older people, especially those who have other health problems, the flu can be very serious and even life-threatening. Getting a flu vaccine every year can help prevent the flu. The vaccine is safe, effective, and available for little to no cost to you.

Most people who get the flu feel better after a few days to two weeks. However, the flu can be serious, and some people will develop other health issues, called complications, because of the flu. Complications can be mild, such as a sinus or ear infection, or more serious, like pneumonia.

Anyone can get sick from the flu, but some people are more likely to have complications. You are more at risk for flu and its complications if you:

• Are age 65 or older
• Have certain medical conditions such as asthma, diabetes, or chronic kidney disease
• Have heart disease or have had a stroke
• Live in a nursing home or other long-term care facility

Pregnant women and children younger than five years old are also more likely to get very sick from the flu. Learn more about people at increased risk for flu and its complications.

Why is the flu more dangerous for older adults?

The flu is more dangerous for older adults for a few reasons. One reason is that the immune system — which helps your body fight infections — weakens as you age. For example, because your body is busy fighting off the flu, you might pick up a second infection such as pneumonia. A second reason is that older adults are also more likely to have other health conditions, like diabetes, that increase their risk for complications from the flu. 

The good news is the flu vaccination reduces your risk of getting the flu and of getting seriously ill if you do get sick with the flu. Flu vaccination is especially helpful for people with chronic health conditions. For example, it has been linked to lower rates of heart problems (cardiac events) among people with heart disease and fewer hospitalizations among people who have chronic lung disease or diabetes. Learn more about the benefits of flu vaccination.

The flu is contagious, which means it spreads from person to person. It mostly spreads through droplets in the air when people with flu cough, sneeze, or talk. It can spread from up to six feet away. Although it isn’t as common, the flu can also spread from surfaces, for example, if you touch something the virus is on and then touch your nose, mouth, or eyes.

It's possible to spread the flu before you feel sick and when you have symptoms. Typically, people with the flu can spread it a day before, and up to a week after feeling sick. Young children and people with weakened immune systems may be able to spread the flu for even longer. If you or someone you know is sick with the flu, take steps to help prevent spreading the disease.

The common cold, flu, and COVID-19 can all cause similar symptoms. If you have symptoms, talk with your health care provider. Your provider can help determine the cause of your illness and help you take steps to feel better.

A cold is often milder than the flu. The flu and COVID-19 have similar symptoms, but COVID-19 spreads more easily and symptoms tend to be more severe. It's also more common to have a change in your sense of smell or taste with COVID-19.

People with the flu can have fever, chills, dry cough, general aches and pains, and a headache. They feel very tired. Sore throat, sneezing, stuffy nose, or stomach problems are less common. What some people call "stomach flu" is not influenza. Learn more about the differences between the flu and a cold and flu and COVID-19.

Common symptoms of a cold, the flu, and COVID-19

The chart below shows common symptoms. Not everyone will have these symptoms. Your symptoms may be more or less severe, or you may only have a few. If you feel sick, stay home and call your doctor 

The most effective way to prevent the flu is to get a flu vaccine every year. Everyone 6 months and older should get a flu vaccine. Getting your flu vaccine reduces your risk of getting the flu. It also reduces your chances of being hospitalized or dying if you do get sick with the flu.

In addition to getting your flu vaccine, you can help stop the spread of flu by:

• Washing your hands
• Covering your mouth when you cough or sneeze
• Staying home when you are sick
• Avoiding close contact with people who are sick

Who should you get a flu vaccine and which one should you choose?

Flu typically spreads in the fall and winter. It usually starts to spread in October and peaks between December and February. That's why this time is called the flu season.

It takes at least two weeks for your flu vaccine to start working, so try to get vaccinated by the end of October. However, getting vaccinated after October can still help protect you from the flu. Because older adults may lose immunity from a flu vaccine more quickly, try to avoid getting vaccinated too early (before September).

Several flu vaccines are available. There are also two types of high-dose vaccinations specifically for people 65 years and older that create a stronger immune response after vaccination. Talk with your health care provider or pharmacist about which vaccine is best for you.

Where can you get a flu vaccine?

You can get your flu vaccine at your doctor's office or from your local health department. Many grocery and drug stores also offer flu vaccines. Visit Vaccines.gov to find a location near you.

Why do you need a flu vaccine every year?

You need a flu vaccine every year for two reasons. First, flu viruses change and the flu vaccine is updated each year to target the flu viruses that are anticipated to spread that year. Second, the protection you get from a flu vaccine lessens with time, especially in older people. Getting your flu vaccine every fall gives you the best protection from that year's flu viruses.

What are the side effects of flu vaccines?

The flu vaccine is safe and cannot give you the flu. Most people have no problem with a flu vaccine.

The most common side effects are soreness, redness, or swelling where you were vaccinated. Some people also get a headache, fever, nausea, or muscle aches. These side effects may start shortly after getting the vaccine and can last up to two days. They typically do not get in the way of daily activities.

Even people with mild egg allergies can safely get most flu vaccines. Egg-free flu vaccines are also available. You should not get vaccinated if you have had a severe allergic reaction to the flu vaccine in the past. Talk with your health care provider about your options for flu vaccines and side effects.

How much does getting a flu vaccine cost?

Most people can get a flu vaccine for little to no out-of-pocket cost. Medicare and most private health insurance plans will cover the cost of your flu vaccine. However, some insurance plans require that you receive your vaccine at a specific location. Check with your insurance company. If you do not have health insurance, contact your local or state health department.

If you get the flu, there are steps you can take to feel better. Act fast! First, talk with your health care provider. The flu and COVID-19 have similar symptoms, so you may need to get tested for an accurate diagnosis. This will also help determine which medications might make you feel better.

There are prescription drugs, called antivirals, that are used to treat people with the flu. If you take them within 48 hours after the flu begins, these drugs can make you feel better more quickly. Antivirals can also help reduce your risk of complications from flu. Antibiotics do not help you recover from the flu. Still, they are sometimes prescribed to help you recover from a secondary infection if it is caused by bacteria. Bacteria are a different type of germ than viruses.

If you are sick, rest and drink plenty of fluids like juice and water, but not alcohol. Medicine, such as acetaminophen or ibuprofen, can bring down your fever and might help with the aches and pains. It is important not to smoke if you are sick with the flu. It is a respiratory illness that can infect your lungs as well as your nasal passages. These same areas are also affected by smoking. Take it easy as much as you can until you are well.

Monitor your symptoms and talk with your doctor if your symptoms worsen or become severe. For example, if you:

• Have a fever that goes away and then comes back. That may be a sign of another infection.
• Start having breathing or heart problems or your other health problems worsen.
• Feel ongoing pain or pressure in the chest or abdomen .
• Continue to feel sick and you are not getting better.
• Have a cough that brings up thick mucus.