The Flu (Influenza)
[Skip to Content]

The Flu (Influenza)

What Is the Flu?

The flu is an infection of the respiratory tract. It's caused by a virus that spreads easily from person to person. Flu season in the United States is from October to May.

What Are the Signs & Symptoms of the Flu?

When people have the flu, they usually feel worse than they do with a cold. Most people start to feel sick about 2 days after they come in contact with the flu virus. They might have:

Babies with the flu also may suddenly seem fussy or just "not look right."

The flu can turn into a serious illness like pneumonia. That can be dangerous for babies and kids or adults with health problems. If you think your child has the flu, see a doctor, nurse, or other medical expert right away.

What Causes the Flu?

The flu gets its name from the that causes it — the influenza virus. It spreads when people cough or sneeze out droplets that are infected with the virus and other people breathe them in. The droplets also can land on things like doorknobs or shopping carts, infecting people who touch these things.

Is the Flu Contagious?

Yes, the flu is very contagious. People can spread it from a day before they feel sick until their symptoms are gone. This is about 1 week for adults, but it can be longer for young kids.

The flu usually happens in small outbreaks. When the illness spreads quickly and infects lots of people in an area at the same time it's called an epidemic. This tends to happen every few years. If an epidemic spreads worldwide, it's called a pandemic.

Who Gets the Flu?

Anyone can get the flu, but kids tend to get it more often than adults. Some very young children or kids with health problems can get very sick and need special care.

How Is the Flu Diagnosed?

Health care providers can often tell by looking if a child has the flu. Because other infections can look like the flu, they might send a mucus sample to a lab for testing. They get the sample by wiping a long cotton swab inside the child's nose or throat.

How Is the Flu Treated?

Most kids with flu get better at home. Make sure your child:

  • drinks lots of fluids to prevent dehydration
  • gets plenty of sleep and takes it easy
  • takes acetaminophen or ibuprofen to relieve fever and aches. Don't give kids or teens aspirin because of its link to Reye syndrome.
  • wears layers that are easy to remove. Kids might feel cold one minute and hot the next.

Children with the flu should stay home from school and childcare until they feel better. They should only go back when they have been fever-free for at least 24 hours without using a fever-reducing medicine. Some kids need to stay home longer. Ask the doctor what's best for your child.

Some children are more likely to have problems when they get the flu, including:

  • kids up to the age of 5, especially babies
  • kids and teens whose immune system is weakened from medicines or illnesses (like HIV infection)
  • kids and teens with chronic (long-term) medical conditions, such as asthma or diabetes
  • kids or teens who take aspirin regularly

They might need medical care, sometimes in the hospital.

Doctors may prescribe antiviral medicine for a very ill child or kids who might have problems. The medicine can shorten the flu by 1–2 days. It only works if children start taking it within 48 hours of the start of the flu. If a doctor prescribes antiviral medicine for your child, ask about any possible side effects.

How Long Does the Flu Last?

Fever and other flu symptoms often go away after 5 days or so, but kids may still have a cough or feel weak. Children's symptoms are usually all gone in a week or two.

Can the Flu Be Prevented?

There's no guaranteed way to avoid the flu. But these steps can make spreading the flu less likely:

  • Wash your hands well and often with soap, especially after using the bathroom, after coughing or sneezing, and before eating or preparing food
  • Never pick up used tissues.
  • Don't share cups and eating utensils.
  • Keep kids home if they have the flu — and stay home if you're sick.
  • Cover your mouth and nose with a tissue when you cough or sneeze, then put it in the trash.
  • If you don't have a tissue, cough or sneeze into your upper arm, not your hands.

What Can Parents Do?

Get the flu vaccine every year. Everyone 6 months of age and older should get a flu vaccine each year.

Most doctor's office, clinics, or pharmacies offer the vaccine from September to mid-November. Even if you miss getting the vaccine at the start of the flu season, it's not too late to get one if the flu is still going around.

If your child is sick, talk to your doctor to see if you need to reschedule the flu shot.

The flu can cause big problems for adults as well as kids. Anyone who has the flu should stay away from people who might get very sick, such as:

  • women who are pregnant, trying to get pregnant, just had a baby, or are breastfeeding
  • babies and young children
  • kids and adults with serious health problems
  • people in hospitals or long-term care facilities, such as nursing homes
  • seniors 65 years and older
Date reviewed: November 2018