Flu (Influenza)

Flu (Influenza) is a viral infection that affects the upper respiratory system, which includes the nose and throat, the airways (also called bronchial tubes), and the lungs. While everyone is at risk for getting the flu, children can be more likely to get sick from this virus.

In young children, women who are pregnant, the elderly, and those with other health conditions, the flu can require them to be hospitalized. In some cases, the flu can be very serious or even deadly.

The experts at Boston Children’s care for children with flu and help them avoid complications like pneumonia that can lead them to become seriously ill.

What are flu symptoms?

Common flu symptoms include:

How long does flu last?

Your child may have some flu symptoms, or all of them. Most symptoms last about a week. But the tiredness may linger longer. If you notice the symptoms are not getting better, or are getting worse, always call your pediatrician.

Flu complications and warning signs

If your child has the flu, it’s important to be on the lookout for any complications. Always seek emergency medical care if you notice the following signs in your child:

  • fast breathing or trouble breathing
  • bluish or gray skin color (cyanosis)
  • not drinking enough fluids
  • severe or persistent vomiting
  • not waking up or not interacting
  • extreme irritability/not wanting to be held
  • flu-like symptoms improve but then return with fever and worse cough

Five things to know about the flu

You probably have many questions about the flu. Dr. Claire McCarthy shares some key facts that can help you keep your family well this winter — and all year long.

Dr. Claire McCarthy shares some key facts that can help you keep your family well.

What causes flu complications in children?

Childhood obesity (when a child is significantly overweight) is one factor that can increase a child’s risk for health complications with the flu.

Other risk factors include:

  • asthma
  • diabetes
  • heart disease
  • kidney disease

How is flu spread?

Flu (influenza) is highly contagious, which means that it can be passed from person to person easily. A person with the flu can spread the virus 24 hours before any symptoms appear.

The influenza virus is typically spread through droplets that are released in the air when someone affected coughs, sneezes, or talks. These droplets, which can travel as far as six feet, may land on the nose or mouth of someone else and make them ill.

The virus can also survive briefly on common surfaces such as doorknobs, phones, tabletops, and faucets. While this is a less common way that flu is spread, when someone touches these surfaces and then touches their nose or mouth, they may become infected.

What are the different types of flu?

Influenza type A and influenza type B

The most common type of flu is seasonal flu, which makes many people sick every year. Seasonal flu is caused by influenza A or influenza B viruses.

H1N1 and other types of flu

There is also a type C virus that causes either mild respiratory symptoms or in some people, no symptoms.

One subtype of Influenza A is called H1N1. In 2009, a new H1N1 virus emerged and caused a pandemic, but that strain has now become one of the circulating seasonal flu viruses.

What is the difference between flu and cold?

The common cold usually takes a few days to progress and usually causes milder symptoms, while the flu can come on more suddenly and the symptoms may be more severe.

It can be difficult to tell whether a person has the flu or other type of viral infection. This makes it important to call your pediatrician if your child becomes sick. Also, be sure to keep them home to prevent spreading the illness.

The symptoms of cold, flu, and COVID-19 appear very similar. The only way to tell the difference is to get testing to identify what is causing your symptoms.

The only way to tell the difference between the flu and COVID-19 is to get testing to identify what is causing your symptoms.