Influenza (Flu) in Children

What is influenza?

Influenza (flu) is a highly contagious viral respiratory illness occurring in annual outbreaks, usually during the winter season.

The most common symptoms of flu are:

  • Fever
  • Muscle aches
  • Sore throat
  • Nonproductive cough

Influenza causes illness in people of all ages. Although most people, including children, have self-limited, uncomplicated illness lasting less than a week, some have more serious illness and may need to be hospitalized. Influenza may also lead to pneumonia or death.

What are the different types of influenza?

Influenza viruses are divided into three types designated as A, B, and C:

  • Influenza types A and B cause epidemics of respiratory illness that occur yearly during the winter. They often lead to increased rates of hospitalization and death. Public health efforts to control the impact of influenza focus on types A and B. One of the reasons the flu remains a problem is because the viruses actually change their structure regularly. This means that people are exposed to new types of the virus each year.
  • Influenza type C is more infrequent and causes either a very mild respiratory illness or no symptoms at all. It does not cause epidemics and does not have the severe public health impact of influenza types A and B.

Influenza viruses continually change (mutate), which helps the virus to evade the immune system of both children and adults. People can get the flu no matter what their age. The process works like this:

  1. A person infected with an influenza virus develops antibodies against that specific virus.
  2. The virus changes.
  3. The "older" antibodies no longer recognize the "newer" mutated virus when the next flu season occurs.
  4. The person becomes infected again.

The older antibodies can give some protection against recurrence of the flu. In addition, the flu vaccine given each year is produced from influenza virus strains expected to cause that year's flu outbreak.

How is influenza transmitted?

Influenza virus is generally passed from person to person in the air through coughing or sneezing. The flu may also be spread by small virus particles released during breathing. The virus can also live for a short time on contaminated objects like doorknobs, pens or pencils, keyboards, telephone receivers, and eating or drinking utensils. So your child can get the flu virus by touching something that has been handled by someone infected with the virus and then touching his or her own mouth, nose, or eyes.

People are generally the most contagious with the flu 24 hours before they start having symptoms and for several days to one week after symptoms first appear. It is difficult to prevent the spread of the flu, especially among children, as they may not always know they are sick while they are still spreading the disease. By the seventh day of infection there is typically no longer a risk of infecting others.

What are the symptoms of influenza?

Influenza is called a respiratory disease, but the whole body seems to suffer when a child has it. Children usually become suddenly ill with any or all of the following symptoms:

  • Fever, which may be as high as 103° F (39.4° C) to 105° F (40.5° C)
  • Muscle and joint aches and pains
  • Not feeling well "all over"
  • Headache
  • Sore throat
  • Runny or stuffy nose
  • Worsening cough
  • Nausea
  • Vomiting
  • Diarrhea
  • Fatigue

Most people recover from influenza within a week, but they often feel exhausted for as long as 3 to 4 weeks. In addition, the cough may be prolonged.

The symptoms of influenza may resemble other conditions or medical problems. Always see your child's healthcare provider for a diagnosis.

How is the flu different from COVID-19?

Both influenza and COVID-19 are respiratory viruses. Because of this, they can cause similar symptoms of cough, difficulty breathing, shortness of breath, fever and body aches. This winter, it will be important to call your child’s pediatrician to discuss symptoms. They may recommend testing to determine which virus your child has. If your child has COVID-19, they will need supportive care and isolation. If your child has influenza, their time at home will just be until symptoms resolve; also, certain children need to receive an antiviral if they have high risk medical conditions. Learn more about symptoms of COVID-19.

How is a cold different from the flu?

A cold and the flu are two different illnesses. A cold is relatively harmless and usually clears up by itself after a period of time. Sometimes a cold may lead to a secondary infection, such as an ear infection. But the flu can lead to complications, such as pneumonia and even death. What may seem like a cold may be the flu. Be aware of these differences:

Cold symptoms

Flu symptoms

Low or no fever

High fever

Sometimes a headache

Headache (very common)

Stuffy, runny nose

Clear nose or stuffy nose


Sometimes sneezing

Mild, hacking cough

Cough, often becoming severe

Slight aches and pains

Often severe aches and pains

Mild fatigue

Several weeks of fatigue

Sore throat

Sometimes a sore throat

Normal energy level or may feel sluggish

Extreme exhaustion

About the influenza vaccine

The Centers for Disease Control and Prevention (CDC) recommends YEARLY flu vaccine for everyone 6 months of age and older.

Children 6 months through 8 years of age require two doses of influenza vaccine separated by four weeks if they:

  • Have never received an influenza vaccine
  • Have not previously received two or more total doses of any flu vaccine
  • Have an uncertain influenza vaccination history

Visit the Vaccine Education Center to learn more about influenza and the influenza vaccine.

What is the treatment for influenza?

Specific treatment for influenza will be determined by your child's primary care provider based on:

  • Your child's age, overall health, and medical history
  • The severity of symptoms
  • Your child's tolerance for specific medications, procedures, or therapies
  • Expectations for the course of the condition
  • Your opinion or preference

The goal of treatment for influenza is to help prevent or decrease the severity of symptoms. Treatment may include:

  • Medications, such as acetaminophen or ibuprofen, to relieve aches and fever. Aspirin is NOT recommended in children.
  • Bed rest
  • Increased fluid intake
  • Medication for your child's cough may be prescribed by your child's provider after a thorough check-up.
  • For anyone in a high-risk group, it’s important that the flu is identified and treated early, to avoid complications.

About flu testing

How does CHOP test for the flu?

CHOP uses a rapid flu test called a “rapid molecular assay” that detects the genetic material of the virus from a nasal swab within 15 minutes. This test can help clinicians decide whether antiviral treatment is necessary for certain high-risk patients.

Who will be tested for the flu?

Only high-risk patients will be tested.

Who is considered high-risk?

  • Children younger than 5 years old (especially those younger than 2) and those older than 65
  • People diagnosed with:
    • Certain respiratory diseases such as asthma
    • Neurological and neurodevelopmental conditions such as seizure disorders
    • Heart disease
    • Disorders of the blood, endocrine system, kidneys, liver or the metabolic system
    • Those with weakened immune systems
    • Those younger than 19 years of age who are receiving long-term aspirin therapy
    • Extreme obesity
    • People with household members who have compromised immune systems, such as family members with cancer who are receiving chemotherapy

What is the treatment if a high-risk patient has the flu?

Antiviral drugs may decrease the severity of symptoms and shorten the course of illness. They may also prevent serious complications, such as pneumonia.

Studies show that antiviral medications for flu work best when they are started within two days of the onset of symptoms.

As with all medicines, some side effects have been associated with the use of flu antiviral drugs, including nausea, vomiting, dizziness, runny or stuffy nose, cough, diarrhea, headache, and some behavioral side effects.

Your clinician will use all of these factors to decide if your child will benefit from rapid flu testing and treatment.

What is the cost of the flu test?

Your insurance company will be billed for the testing, but different insurers vary in whether or not they will cover (or partially cover) the cost of the test. Deductibles, copays and coinsurance may apply. Contact your insurance company to determine if you will be charged an additional fee for testing.

Reviewed by Debra D. Weissbach, MD, FAAP, Scott C. Tomaine, DO, Geraldine O'Hare, MSN, CRNP

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