RELATED STORIES • Chickenpox • Measles study stresses importance of routine vaccination • Roseola • Hand-foot-and-mouth disease • Chickenpox vaccine: Is it always effective? • Coxsackievirus infection INFECTIOUS DISEASE Viral Illnesses • Chickenpox • Mumps • Postherpetic neuralgia • Croup • Measles • Rubella • Mononucleosis • Smallpox • Parvovirus infection • West Nile virus • Roseola • Rabies • SARS • Viral hemorrhagic fevers • Polio • Hand-foot-and-mouth disease

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Croup has an unmistakable sound — a harsh, repetitive cough similar to the noise of a seal barking. Attacks of croup often jar children awake and leave them frightened and gasping for breath. Croup can be scary for parents, too, but it's usually not serious. At its worst, croup can be treated in the doctor's office most of the time.

The harsh, barking cough is the result of swelling around the vocal cords (larynx) and windpipe (trachea). When the cough reflex forces air through this narrowed passage, the vocal cords vibrate with a barking noise. Because children have small airways to begin with, those younger than age 5 are most susceptible to croup.

Fluids, moist air and other self-care measures can speed recovery from croup. If you stay calm, you can quiet your child's cough so that everyone can get back to sleep.

The classic sign of croup is a loud, harsh, barking cough — which often comes in bursts at night. Your child's breathing may be labored or noisy. Fever and a hoarse voice are common, too.

Croup is often caused by the parainfluenza virus. Less often, respiratory syncytial virus, the measles virus or various other viruses cause croup.

Your child may contract a virus by breathing infected respiratory droplets coughed or sneezed into the air. Virus particles in these droplets also may survive on toys and other surfaces. If your child touches a contaminated surface and then touches his or her eyes, nose or mouth, an infection may follow.

Rarely, croup may be caused by a bacterial infection.

Croup is most common in children age 5 and younger — particularly those who were born prematurely. Signs and symptoms are typically most severe in children age 3 and younger.

Most cases of croup can be treated at home. Seek immediate medical attention if your child:

• Makes noisy, high-pitched breathing sounds when inhaling (stridor)
• Begins drooling or has difficulty swallowing
• Seems agitated or extremely irritable
• Struggles to breathe
• Develops blue or grayish skin around the nose, mouth or fingernails

Croup is typically diagnosed based on symptoms and a physical exam. The doctor will observe your child's breathing, listen to your child's chest with a stethoscope and examine your child's throat. Sometimes X-rays or other tests are used to help make the diagnosis.

Most cases of croup are mild. Rarely, the airway swells enough to interfere with breathing. Ear infection and pneumonia are other rare but potentially serious complications.

Self-care measures at home — such as breathing moist air and drinking fluids — can speed your child's recovery. More aggressive treatment is rarely needed.

If your child's symptoms persist or worsen, his or her doctor may prescribe corticosteroids, epinephrine or another medication to open the airways. Antibiotics are effective only if your child has a bacterial infection.

For severe croup, your child may need to spend time in a humidified oxygen tent. Rarely, a temporary breathing tube may need to be placed in a child's windpipe.

Croup can be scary — especially if it lands your child in the doctor's office, hospital or emergency room. Hold your child, sing lullabies or read quiet stories. Offer a favorite blanket or toy. Speak in a soothing voice. Your presence can help keep your child calm.

To prevent croup, take the same steps you use to prevent colds and flu. Frequent hand washing is most important. Also keep your child away from anyone who's sick, and encourage your child to cough or sneeze into his or her elbow.

To stave off more serious infections, keep your child's immunizations current. The diphtheria, Haemophilus influenzae type b (Hib) and measles vaccines offer protection from some of the rarest — but most dangerous — forms of croup.

Croup often runs its course within three to seven days. In the meantime, keep your child comfortable with a few simple measures.

• Stay calm. Comfort or distract your child — cuddle, read a book or play a quiet game. Crying only makes breathing more difficult.
• Moisten the air. Use a humidifier in your child's bedroom, or have your child breathe the warm, moist air in a steamy bathroom. Although researchers have questioned the benefits of humidity as part of emergency treatment for croup, moist air seems to help children breathe easier — especially when croup is mild.
• Get cool. Sometimes breathing fresh, cool air helps. If it's cool outdoors, wrap your child in a blanket and walk outside for a few minutes.
• Hold your child in an upright position. Sitting upright can make breathing easier. Hold your child on your lap, or place your child in a favorite chair or infant seat.
• Offer fluids. For babies, water, breast milk or formula is fine. For older children, soup or frozen fruit pops may be soothing.
• Encourage your child to rest. Sleep can help your child fight the infection.
• Try an over-the-counter pain reliever. If your child has a fever, acetaminophen (Tylenol, others) may help. Cough syrup, which doesn't affect the larynx or trachea, isn't likely to relieve your child's cough.

Your child's cough may improve during the day, but don't be surprised if it returns at night. You may want to sleep near your child or even in the same room so that you can take quick action if your child's symptoms become severe.