Influenza (Flu): What You Need to Know

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Influenza is an illness caused by the influenza virus. While most people experience respiratory symptoms, influenza affects the whole body. Influenza is commonly known as the flu, and both terms will appear throughout this publication. This is not the same as what we often call the "stomach flu."

Each year, the flu season is a little different because there are different types of influenza viruses and they change over time, so people can get the flu many times in their life. In the United States, flu season generally occurs in the fall and winter, but some seasons can extend into the spring.

Here is more information from the American Academy of Pediatrics (AAP) about influenza.

Signs of Influenza

The flu usually lasts a week or longer. Your child usually will feel the worst during the first 2 or 3 days. Signs and symptoms of the flu include

  • A sudden fever (temperature usually above 101.0F or 38.3C)

  • Chills and shakes with the fever

  • Sore throat and/or dry, hacking cough

  • Headache, body aches, and extreme tiredness

  • Stuffy, runny nose

  • Throwing up (vomiting) and loose, runny stools (diarrhea)

Is it the flu or a cold?

Both the flu and the common cold are caused by viruses. In general, it may be hard for you to tell them apart because they can have some of the same symptoms. But there are some differences.

Flu Versus Cold

Signs and Symptoms Flu Cold
Symptom onset Abrupt Gradual
Fever Usual Rare
Aches Usual Slight
Chills Fairly common Uncommon
Fatigue, weakness Usual Sometimes
Sneezing Sometimes Common
Chest discomfort, cough Common Mild to moderate
Stuffy nose Sometimes Common
Sore throat Sometimes Common
Headache Common Rare

Source: Centers for Disease Control and Prevention. Cold versus flu. https://www.cdc.gov/flu/symptoms/coldflu.htm. Accessed May 18, 2020.

When to Call the Doctor

Call the doctor

  • Right away if your child is younger than 2 years and has a temperature of 100.4F (38.0C) or higher during the flu season.

  • Within 24 hours if your child is older than 2 years and shows signs of flu.

The doctor may be able to treat influenza with an antiviral drug. But this only works if your child gets the drug in the first day or two of illness. Keep in mind that antiviral drugs are not the same as antibiotics, which don't help treat influenza.

Often there are no serious problems with influenza. But sometimes your child can get an ear infection, a sinus infection, pneumonia, or other complications of the flu.

At any age, call the doctor if your child has one of these signs with the flu.

  • Trouble breathing

  • A cough that won't go away after a week

  • Pain in the ear

  • Fever that continues or comes back after 3 to 4 days

  • Does not start to feel better after a few days

How to Care for Your Child

  • Make sure your child gets extra rest.

  • Make sure your child drinks plenty of liquids to avoid getting dehydrated.

  • Ask your child's doctor about pain and fever medicine. Two types of medicines for pain and fever are acetaminophen and ibuprofen. Tylenol is one brand of acetaminophen. Advil and Motrin are brands of ibuprofen. For a baby 6 months or younger, give acetaminophen. For a baby or child older than 6 months, give either acetaminophen or ibuprofen. Both of these drugs help with fever. They are not the same. Be sure to get the right kind of medicine for your child's age. Follow what the label says.

  • Check with your child's doctor before giving your child any other medicines. This includes over-the-counter cold and cough medicines. Also, never give your child aspirin. It can be dangerous for children younger than 18 years.

  • Don't smoke around your child. Smoke makes children cough and wheeze more. And it makes it harder for them to get over influenza.

How to Prevent Influenza

The flu spreads very easily, especially to children and adults who spend time with children. It usually spreads during the first several days of the illness.

There are 2 ways to prevent influenza.

Influenza vaccines

Getting the flu vaccine is the best way to prevent influenza.

There are safe vaccines to protect against influenza. They come as shots and a nose spray. Ask your child's doctor what is best for your child. All babies and children 6 months and older need an influenza vaccine every fall. All their family members should get the vaccine too. Call your child's doctor to find out more.

Good hygiene

Keeping germs from spreading is the best way to avoid spreading the flu. These tips will help protect your family from getting sick.

  • Teach your child to cover his or her mouth and nose when coughing or sneezing. Show your child how to use a tissue or a sleeve, not a hand.

  • Use tissues for runny noses and then throw the tissue away. Wash your hands afterwards. Throw them in the trash right away.

  • Avoid kissing a sick child on the mouth or face.

  • Make sure everyone washes their hands often.

  • Wash dishes, spoons, and forks in hot, soapy water or the dishwasher.

  • Don't let children share pacifiers, cups, spoons, forks, washcloths, or towels. Never share toothbrushes.

  • Wash doorknobs, toilet handles, countertops, and even toys. Use a household cleaning spray or wipes and follow the instructions on the label.


If you have any questions or concerns about your child's health, contact your child's doctor.


Any websites, brand names, products, or manufacturers are mentioned for informational and identification purposes only and do not imply an endorsement by the American Academy of Pediatrics (AAP). The AAP is not responsible for the content of external resources. Information was current at the time of publication. The information contained in this publication should not be used as a substitute for the medical care and advice of your pediatrician. There may be variations in treatment that your pediatrician may recommend based on individual facts and circumstances. Information applies to all sexes and genders; however, for easier reading, pronouns such as he are used in this publication.