Croup :: Nationwide Children's Hospital

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Croup is an illness that is usually caused by a virus. It causes the tissues that line the windpipe (trachea) to become red and swollen below the voice box (larynx). This swelling blocks the flow of air into the lungs.

Croup may come on suddenly in the night or during the day. It usually lasts 5 to 6 days and is more severe at night. Croup occurs most often during the fall season, but it can occur year round. It usually affects children 6 months to 3 years of age. Croup is very contagious (catching) until after the fever is gone. A child who has croup once may get it again.

There is no medicine that will get rid of the virus, but you can do some things to help your child breathe easier until the infection goes away. It will help to know ahead of time what to do so you can stay calm if croup develops.

Picture 1 - Stay with your child and let him breathe in the steam.
Image of steam treatment

What You Will Hear and See

Your child may have trouble breathing. Breathing may be noisy, especially when he or she breathes in. The cough sounds like a seal's bark and may get worse over several days. His or her voice may sound hoarse or muffled. When he breathes in, you may hear a "crowing" sound.

Your child may look frightened and be restless, upset, and excited. If your child's face turns blue or dusky, call 911 or the emergency squad.

What to Do

  1. Stay calm and try to keep your child calm.
  2. Run a cool mist vaporizer in your child's room when he is sleeping. Open the window a little to cool the air.
  3. If breathing becomes more noisy and difficult, place your child directly in front of the vaporizer so that he can breathe in the mist. If you don’t have a cool mist vaporizer, take your child into the bathroom and shut the door (Picture 1). Turn on the shower and hot water faucets to make steam. Be careful to keep away from the hot water. Stay with your child and let him breathe in the steam. Do not leave your child alone.
  4. If the steam does not seem to help your child, dress him warmly and take him into the cool night air. The cool air will help to decrease the swelling in the windpipe. If the outside air is not cool, open the refrigerator or freezer and let your child breathe in the cool air.
  5. When breathing is easier for your child – after 10 to 15 minutes - give him sips of water. Later, give additional clear, warm liquids to drink such as warm apple juice, lemonade or herbal tea. Warm liquids help to relax the vocal chords and loosen sticky mucus. Drinking plenty of liquids is very important in helping your child get over croup.
  6. Take your child's underarm temperature (see below).

How to Take an Underarm Temperature

The normal axillary (underarm) temperature is 97.6 F.

Picture 2 - Taking an axillary temperature.
Image of underarm temperature

To take this temperature:

  1. Use a thermometer with a long bulb.
  2. Make sure the child's underarm space is dry.
  3. Place the thermometer under the child's arm (Picture 2).
  4. Keep your child's arm close to his body to help keep the thermometer in place.
  5. Stay with your child and hold the thermometer in place for 10 minutes.
  6. Remove the thermometer and read it.

If Your Child Was Treated in the Emergency Room

If your child was treated in the Emergency Room and the symptoms of croup occur again at home, follow the instructions in What to Do.

When to Call the Doctor

Call your child's doctor (phone) if:

  • Your child does not improve after being in a steamy bathroom for 10 to 15 minutes (or after you have taken your child out into the cold night air).
  • Breathing becomes more difficult (the hollow in the child’s neck or the chest continues to "pull in").
  • Your child drools.
  • Your child has trouble swallowing; if he suddenly refuses to drink liquids.
  • The skin is blue around your child’s mouth.
  • Your child has fever over 102F (axillary) for more than 3 days.
  • Your child has croup that lasts more than 10 days.

If you have any questions, please call your doctor.

Croup (PDF)

HH-I-19 4/78, Revised 9/11 Copyright 1978-2011, Nationwide Children’s Hospital