As miserable as a cough can make your kid -- and you -- it does serve an important purpose: "That forceful exhalation of air propels mucus, bacteria, and other irritants out of the airways," explains Thomas Ferkol, M.D., director of pediatric allergy and pulmonary medicine at Washington University, in St. Louis. While that's all well and good, relief is all anyone really wants. The key to finding it? Knowing what's causing the hack to begin with. The chart below can get you on the road to peace. (Visit Child Health Guide to hear what these coughs sound like.) In the meantime, watch out for certain danger signs: If your child's been coughing for more than two weeks or develops a high fever, take her to the pediatrician. If she has trouble breathing, begins turning blue, or can't eat or swallow, head straight to the ER. And if you're tempted to give her an over-the-counter cough medicine, hold up. Studies show they're not effective, and some may even be harmful.

If your kid's cough is:

WET AND PRODUCTIVE

It means: she has mucus to clear out of her airways, or she's got postnasal drip
The likely cause is: an infection (such as a cold, sinusitis, or pneumonia), or allergies
For sweet relief: Use saline nose drops, and offer her lots of fluids to thin the mucus. If she's got a fever along with the cough, call the doctor to rule out a more serious infection.

DRY AND RASPY

It means: there's irritation somewhere in her airways
The likely cause is: an infection, allergen, or other irritant, such as dust, pollen, or smoke, that produces little or no mucus
For sweet relief: Soothe it as you would a wet cough, with nose drops and lots of fluids. If you suspect the cough is allergy-related, do your best to limit your child's exposure and wait it out.

SOUNDING LIKE A BARKING SEAL OR DOG

It means: her airways are constricted and/or inflamed
The likely cause is: croup, a viral infection that's usually worse during the night
For sweet relief: Sit with her in a steamy bathroom for 15 to 20 minutes, or go outside in the fresh air if it's cool (not cold). If she's having significant trouble breathing, go to the ER.

ACCOMPANIED BY WHEEZING

It means: she has mucus to clear out of her airways, or she's got postnasal drip
The likely cause is: asthma, or bronchiolitis, an infection of the lungs' small airways that's usually seen in kids under 3
For sweet relief: See the doctor to find out exactly what's going on. If your child has asthma, her medication may need tweaking. If she has an infection, she may need antibiotics.

A SEVERE COUGHING FOLLOWED BY A "WHOOP"

It means: she's literally coughing all the air out of her lungs, then taking in a deep breath
The likely cause is: whooping cough, a bacterial infection known as pertussis
For sweet relief: Call the doctor at once. He may prescribe antibiotics to make your child less contagious, but these won't treat the cough or shorten its duration. This can be a dangerous infection in babies, which is why staying on top of the pertussis shot is so important.

CLOSE PRINT

A Guide to Kids' Coughs What's that sound? This chart helps decipher your child's coughs By Maura Rhodes, Parenting As miserable as a cough can make your kid -- and you -- it does serve an important purpose: "That forceful exhalation of air propels mucus, bacteria, and other irritants out of the airways," explains Thomas Ferkol, M.D., director of pediatric allergy and pulmonary medicine at Washington University, in St. Louis. While that's all well and good, relief is all anyone really wants. The key to finding it? Knowing what's causing the hack to begin with. The chart below can get you on the road to peace. (Visit Child Health Guide to hear what these coughs sound like.) In the meantime, watch out for certain danger signs: If your child's been coughing for more than two weeks or develops a high fever, take her to the pediatrician. If she has trouble breathing, begins turning blue, or can't eat or swallow, head straight to the ER. And if you're tempted to give her an over-the-counter cough medicine, hold up. Studies show they're not effective, and some may even be harmful. If your kid's cough is: WET AND PRODUCTIVE It means: she has mucus to clear out of her airways, or she's got postnasal drip The likely cause is: an infection (such as a cold, sinusitis, or pneumonia), or allergies For sweet relief: Use saline nose drops, and offer her lots of fluids to thin the mucus. If she's got a fever along with the cough, call the doctor to rule out a more serious infection. DRY AND RASPY It means: there's irritation somewhere in her airways The likely cause is: an infection, allergen, or other irritant, such as dust, pollen, or smoke, that produces little or no mucus For sweet relief: Soothe it as you would a wet cough, with nose drops and lots of fluids. If you suspect the cough is allergy-related, do your best to limit your child's exposure and wait it out. SOUNDING LIKE A BARKING SEAL OR DOG It means: her airways are constricted and/or inflamed The likely cause is: croup, a viral infection that's usually worse during the night For sweet relief: Sit with her in a steamy bathroom for 15 to 20 minutes, or go outside in the fresh air if it's cool (not cold). If she's having significant trouble breathing, go to the ER. ACCOMPANIED BY WHEEZING It means: she has mucus to clear out of her airways, or she's got postnasal drip The likely cause is: asthma, or bronchiolitis, an infection of the lungs' small airways that's usually seen in kids under 3 For sweet relief: See the doctor to find out exactly what's going on. If your child has asthma, her medication may need tweaking. If she has an infection, she may need antibiotics. A SEVERE COUGHING FOLLOWED BY A "WHOOP" It means: she's literally coughing all the air out of her lungs, then taking in a deep breath The likely cause is: whooping cough, a bacterial infection known as pertussis For sweet relief: Call the doctor at once. He may prescribe antibiotics to make your child less contagious, but these won't treat the cough or shorten its duration. This can be a dangerous infection in babies, which is why staying on top of the pertussis shot is so important.