Croup is caused by a viral infection of the vocal cords. An older person getting the same laryngitis would probably only have a hoarse voice and some cough. Hoarseness is due to swelling of the vocal cords. The stridor is due to narrowing of the airway. This narrowing is more apparent in small children because their air passages are small to begin with.

Moist air is the most effective treatment for croup. Taking a child with croup into the bathroom, with the door closed and the warm shower running, may improve the cough and stridor within a few minutes. Continued treatment with mist in the bedroom will help reduce the swelling of the vocal cords, make the child's breathing easier, and encourage peaceful sleep. If the stridor is not relieved by the thick steamy air of the bathroom, the symptoms can sometimes be reduced by exposure to cool night air. Dress your child in a coat and expose him to five minutes of cool outside air. If the stridor subsides then return to the humidified bedroom and continue to monitor your child's progress. If stridor does not subside, your child needs further medical evaluation and treatment beyond what can be done at home. Contact your child's pediatrician for instructions. The doctor may advise a trip to the emergency room.

Mist is best provided with a cool mist humidifier. It is important to keep the humidifier clean and dry between uses so that it does not grow mold. Put only clean water in the humidifier when you use it. The humidifier running in the bedroom, or in another room with the child during the day, usually provides all the mist that is needed.

Hot steam vaporizers, for reasons of safety, because the humidifier puts more moisture into the air, and because some children are made worse if the moist air is too warm. Dry air usually makes the cough worse. Wood smoke and tobacco smoke are irritants which can make some children's croup much worse.

Children with croup should drink as much water and other clear liquids as possible, but some children don't seem to tolerate milk during croup. Elevating your child's head during sleep, or raising the upper end of the mattress nearly to a sitting position, may make breathing easier.

Cough medicines are usually not of any value for croup. However, if the croup is very severe, your child's doctor after examining your child may reduce swelling in the area of the vocal cords.

Croup is very contagious from the beginning of symptoms until the fever is gone, and for a minimum of 3 or 4 days. Be particularly careful to keep your child with croup away from small babies and elderly people.

Croup usually begins to improve in 3 to 5 days. When it gets better the symptoms may disappear altogether, or the cough may get looser and sound more like a typical chest cold. When this occurs, while you may still want to use the humidifier, it may not be necessary to use it continuously day and night. Cough medicines may be helpful at this time.

When your child has croup, you will want to sleep in the same room, or close enough so that you can easily hear his breathing. If your child's breathing becomes labored, or if the stridor does not clear up after 20 minutes of mist treatment in the bathroom or in a tent, you should contact your child's doctor or the doctor on call immediately. If breathing is so difficult that it causes retraction between the ribs, you should call immediately. You should also call immediately if your child has great difficulty swallowing. If your child's lips turn blue, or if your child starts drooling, immediately call 911.

You should see your doctor within 24 hours if your child with croup has a high fever (103º or 104º), is not drinking enough liquids, has several spells of stridor, seems to be getting worse, or isn't improving within 3 or 4 days. And if you are worried, please call you doctor.