Croup is a common infection in children. It causes swelling in the upper part of the airway in the neck. It causes a barking cough, with or without fever. And it may cause problems with breathing. The illness is seen more often in the winter.

A virus is the most common cause of croup. But the illness may also be caused by bacteria, allergies, or reflux from the stomach. Viruses that are known to cause croup are:

• Parainfluenza virus
• Respiratory syncytial virus (RSV)
• The flu (influenza virus)
• Adenovirus
• Enteroviruses
• COVID-19

Croup is spread through direct contact with an infected person or their body fluids. The infection starts in the nose and throat and moves into the lungs. Swelling affects the area around the voice box (larynx) and into the windpipe (trachea).

Younger children are more affected by croup because their airways are smaller. A small amount of swelling can make it very hard for a baby or young child to breathe. Croup is most often seen in children 3 months to 5 years old. The peak time for croup to occur is 2 years old.

The symptoms of croup are not always the same. As the illness moves from the nose to the lungs, the symptoms can change. They may include:

• A runny or stuffy nose and slight cough
• A cough that turns into a “seal's bark”
• Losing their voice (laryngitis) or having a hoarse cry
• Fever
• A high-pitched “creaking” or whistling sound when breathing in (stridor)

These symptoms are often worse at night and may wake your child from sleep. They may also seem to get better in the morning but get worse as the day goes on. Most children feel better in 3 to 7 days.

The symptoms of croup can be mistaken for other health problems. Make sure your child sees their doctor for a diagnosis.

Your child's doctor can diagnose croup with a health history and physical exam. Your child may need tests if the doctor thinks they may have other illnesses. A neck X-ray, chest X-ray, or both may be ordered.

Treatment will depend on your child's symptoms, age, and general health. It will also depend on how severe the condition is.

In severe cases of croup, or if your child is not breathing well, your child may need to go to the hospital. You can manage most milder cases at home. But it can sometimes be hard to tell if your child needs to go to the hospital because the illness changes. Your child may seem better one moment and then get worse the next. Your child's doctor may order the following medicines to help ease symptoms:

• Inhaled medicines. These are used if your child is having a lot of trouble breathing. Inhaled treatments may be used to ease the whistling sound (stridor) and make it easier to breathe.
• Steroids. An injectable steroid is often given if the child can't take steroids by mouth (oral). This medicine can help prevent the illness from getting worse.
• Other medicines. Your child's doctor may prescribe other medicines if they feel your child's croup is from allergies or reflux. The doctor may also recommend acetaminophen or ibuprofen for a fever or discomfort. Antibiotics are not useful if the illness is caused by a virus.

For a milder case, these methods may help at home:

• Have your child rest and drink plenty of fluids.
• Don't smoke in the home. Smoke can make your child's cough worse.
• Keep your child's head raised. Prop an older child up in bed with extra pillows. Never use pillows with babies younger than 12 months.
• Sleep in the same room as your child to help your child right away if they start to have trouble breathing.
• Stay calm. If your child sees that you are frightened, it will increase their anxiety and trouble breathing.
• Comfort your child. Sing your child's favorite bedtime song or offer a favorite toy.

Breathing in steam or cool night air may also help your child breathe easier. You may want to try:

• Putting a humidifier in your child's room
• Putting a warm, wet washcloth over your child's nose and mouth as they breathe
• Creating a steam room in your bathroom. Turn on the hot water in your bathroom shower. Keep the door closed so the room gets steamy. Sit with your child in the steam for 15 to 20 minutes. Don't leave your child alone.
• If your child wakes up at night, try bundling them up and going outside to breathe in the cool night air.

Here are tips to prevent the spread of croup:

• Wash your hands often. Teach your child how to correctly wash their hands.
• Stop your child from sharing cups and other dishware.
• Keep your child at home until they are better.

Call 911 right away if your child:

• Makes a whistling sound (stridor) that becomes louder with each breath.
• Has stridor when resting.
• Has a hard time swallowing their saliva, or drools.
• Has increased trouble breathing.
• Has a blue or dusky color around the fingernails, mouth, or nose.
• Struggles to catch their breath.
• Can't speak or make sounds.

Call your child's doctor right away if your child:

• Has a fever (see Fever and children, below).
• Has a cough or other symptoms that don't get better or that get worse.
• Doesn't get better within a week.
• Has a fever that goes down but they still “act sick.”
• Has a seizure.

Use a digital thermometer to check your child's temperature. Don't use a mercury thermometer. There are different kinds and uses of digital thermometers. They include:

• Rectal. For children younger than 3 years, a rectal temperature is the most accurate.
• Forehead (temporal). This works for children age 3 months and older. If a child under 3 months old has signs of illness, this can be used for a first pass. The doctor may want to confirm with a rectal temperature.
• Ear (tympanic). Ear temperatures are accurate after 6 months of age, but not before.
• Armpit (axillary). This is the least reliable but may be used for a first pass to check a child of any age with signs of illness. The doctor may want to confirm with a rectal temperature.
• Mouth (oral). Don't use a thermometer in your child's mouth until they are at least 4 years old.

Use a rectal thermometer with care. Follow the product maker's directions for correct use. Insert it gently. Label it and make sure it's not used in the mouth. It may pass on germs from the stool. If you don't feel okay using a rectal thermometer, ask the doctor what type to use instead. When you talk with any doctor about your child's fever, tell them which type you used.

Below is when to call the doctor if your child has a fever. Your child's doctor may give you different numbers. Follow their instructions.

When to call a doctor about your child's fever

For a baby under 3 months old:

• First, ask your child's doctor how you should take the temperature.
• Rectal or forehead: 100.4°F (38°C) or higher
• Armpit: 99°F (37.2°C) or higher
• A fever of ___________as advised by the doctor

For a child age 3 months to 36 months (3 years):

• Rectal or forehead: 102°F (38.9°C) or higher
• Ear (only for use over age 6 months): 102°F (38.9°C) or higher
• A fever of ___________ as advised by the doctor

In these cases:

• Armpit temperature of 103°F (39.4°C) or higher in a child of any age
• Temperature of 104°F (40°C) or higher in a child of any age
• A fever of ___________ as advised by the doctor

• Croup is a common infection in children. It is most often caused by a virus. It causes swelling in the upper part of the airway in the neck.
• Children with croup have trouble breathing because their small airways swell.
• Common symptoms include a barking cough, fever, runny nose, and high-pitched “creaking” or whistling sound (stridor) when breathing in.
• Most cases are mild and can be managed at home. A child who has a lot of breathing problems may need to go to the hospital.
• Correct handwashing is one way to prevent croup.

Tips to help you get the most from a visit to your child's doctor:

• Know the reason for the visit and what you want to happen.
• Before your visit, write down questions you want answered.
• At the visit, write down the name of a new diagnosis and any new medicines, treatments, or tests. Also write down any new instructions your doctor gives you for your child.
• Know why a new medicine or treatment is prescribed and how it will help your child. Also know what the side effects are.
• Ask if your child's condition can be treated in other ways.
• Know why a test or procedure is recommended and what the results could mean.
• Know what to expect if your child does not take the medicine or have the test or procedure.
• If your child has a follow-up appointment, write down the date, time, and purpose for that visit.
• Know how you can contact your child's doctor after office hours and on weekends and holidays. This is important if your child becomes ill and you have questions or need advice.