It’s always distressing to hear your little one cough, especially in the middle of the night—but this common wintertime symptom often sounds worse than it really is.

“Coughing is the body’s way of clearing and protecting the airways from irritating mucous and other secretions,” says Charles Shubin, M.D.

Coughs also provide valuable clues about your child’s illness. Follow our guide to figure out what’s worrisome and what’s not—and help your child feel better fast.

Cough Clues: A distinctive, shrill, dry, seal-like bark, which frequently starts in the middle of the night.

“The sound is unlike any cough you’ve ever heard before,” says pediatrician Mark Widome, M.D., author of “Ask Dr. Mark.”

Other Symptoms: Your child’s illness follows a circadian rhythm: better during the day, worse at night. She may have a slight fever. In severe cases, your child may develop stridor, a harsh, high-pitched sound every time she inhales—similar to the noise kids make after a long crying jag.

Likely Culprit: CROUP, a contagious wintertime viral infection that causes the throat and windpipe to swell and narrow. It typically affects kids between 6 months and 3 years. (Adults and older children have wider windpipes, so swelling is less likely to affect breathing.)

What to Do: Sit with your child in a steamy bathroom for five minutes; the humidity will help move mucus from her lungs and calm her cough. “After that, bundle her up in warm pajamas and take her out into the cool night air for a few minutes or open the freezer in the kitchen and have your child breathe in the frigid air,” says pediatrician Bonnie Kvistad, M.D. The combination of steam then cool air can help reduce airway inflammation. At bedtime, run a cool-mist humidifier in the room; the cold, moist air may reduce airway swelling as well.

Call your doctor right away if your child is less than 2 to 3 months old, her cough worsens or she’s having trouble breathing. She may need medicine to reduce inflammation. Otherwise, croup often runs its course in three to four days.

Cough Clues: A wet or dry, hacking cough without wheezing or fast breathing, day or night.

Other Symptoms: Sneezing, a runny nose, watery eyes, and a mild fever (usually less than 101.5 degrees F).

Likely Culprit: COMMON COLD, a viral infection of the nose, sinuses, throat, and large airways of the lungs. Coughing usually lasts the entire length of the cold (about seven to 10 days) but can linger twice as long, with mild improvement each day.

What to Do: Keep nasal passages as clear as possible; congestion and postnasal drip worsen his cough. Using a cool-mist humidifier in your child’s bedroom will help moisten airways to reduce the coughing caused by post-nasal drip. For babies and toddlers who can’t blow their nose yet, use nasal saline drops and a nasal aspirator to suction a runny nose. Children’s Tylenol or Ibuprofen can keep him comfortable if he has a fever but check with your doctor for the right dose if your child is under age 2.

If your child’s cough and stuffy nose persist for more than 10 days without improving, see your doctor. Your little one could have asthma, allergies or even enlarged adenoids, which inhibit breathing. Older kids could have sinusitis (a bacterial infection that’s often brought on by a cold).

Cough Clues: A wheezy, crackly, persistent cough after your child eats. Coughing episodes typically worsen when she’s lying down.

Other Symptoms: She may feel a burning sensation or may vomit or belch when swallowing. A baby might be fussy or have been labeled as colicky. Toddlers may develop wheezing and picky eating habits.

Likely Culprit: GERD (gastroesophageal reflux disease), caused by a weak or immature band of muscle between the esophagus and stomach that allows acid to flow back up. Sometimes the irritating juices can enter the lungs, causing a chronic cough.

What to Do: See your pediatrician if your child’s wheezy cough lasts longer than two weeks. He may recommend keeping your baby upright for at least 30 minutes after feedings and elevating the head of her mattress while she sleeps. Prescription medicine can also control GERD symptoms.

Cough Clues: Dry, hacking coughing fits—as many as 25 coughs in a single breath.

When your child inhales sharply to catch her breath, she makes a high-pitched whooping sound.

Other Symptoms: Before the cough starts, your child has a week of cold-like symptoms but no fever. In infants, the illness can be severe and cause mucus to bubble from the nostrils. It can also lead to convulsions and make a baby stop breathing if she gets tired.

Likely Culprit: WHOOPING COUGH (also known as pertussis), a highly contagious bacterial infection of the throat, windpipe and lungs. Babies routinely get their shots 2, 4, and 6 months and additional booster at 15 months and again between 4 and 6 years. Children who haven’t received their full immunizations are most vulnerable. All adults, especially those in close contact with infants younger than 12 months, such as parents, grandparents, babysitters and nannies, get the Tdap (tetanus, diphtheria, and pertussis) vaccine and a booster every 10 years. Immunity wanes as we get older. Therefore, adults may carry pertussis but get only a mild cough.

What to Do: Call your doctor if your child’s cough worsens instead of getting better after a week. Babies usually need to be hospitalized to control the cough and have mucus suctioned from their throat. The illness is treated with antibiotics, though the cough can last for many weeks or even months. “Whooping cough is very contagious so children who are not fully immunized who have been in contact with somebody with whooping cough should see their pediatrician. They may be given prophylactic antibiotics,” Dr. Kvistad says.

Cough Clues: A mildly hoarse, throaty cough that comes in frequent spells and can be either wet or dry.

Other Symptoms: Your child feels listless and complains that his throat is scratchy and sore, his head hurts, and the muscles in his back and legs ache. He may also have a runny nose, fever and nausea.

Likely Culprit: FLU, a viral respiratory illness that’s most common from November through April.

What to Do: Call your doctor if your child has a fever above 101.5 degrees F, is throwing up, has diarrhea, or is uninterested in eating or drinking (your doctor will recommend steps to prevent dehydration).

Give your child plenty of fluids, and use a humidifier to loosen congestion in his airways. Also, to ward off future bouts of the flu, ask your pediatrician about getting your child an annual flu shot; it’s recommend for children 6 months of age and older. It’s not expected to protect against the swine flu (H1N1), which has similar symptoms to seasonal flu. Ask your pediatrician for more information.

Cough Clues: A persistent cough that’s often whistling or wheezy, lasts longer than ten days, and worsens at night or after your child exercises or is exposed to pollen, cold air, animal dander, dust mites or smoke.

Other Symptoms: Your child is wheezing or has labored, rapid breathing.

Likely Culprit: ASTHMA, a chronic condition in which small airways in the lungs swell, narrow, become clogged with mucous, and spasm, making breathing difficult. Common asthma triggers include environmental irritants, viral infections, and exercise. “Children with asthma, in essence, have sensitive lungs,” says Dr. Widome.

What to Do: In mild asthma cases, a chronic cough may be the only symptom, Dr. Widome says. See your doctor for an accurate diagnosis. Mention any family history of allergy, asthma or eczema, which can increase your child’s likelihood of the disease.

Cough Clues: A phlegmy or wheezy cough that’s often accompanied by fast, shallow or difficult breathing.

Other Symptoms: Your child starts out with cold symptoms, such as sneezing or a stuffy or runny nose, that last about a week, and may develop a fever up to 103 degrees F. He’s lethargic and makes a wheezing sound when he exhales.

Likely Culprit: BRONCHIOLITIS, an infection of the tiny lower airways in the lungs called bronchioles. It’s usually caused by respiratory syncytial virus (RSV) and most often occurs from late fall to early spring. Not to be confused with bronchitis (a frequent upper-respiratory infection in older kids and adults), bronchiolitis is common among babies and toddlers. “RSV is different than the common cold, but it’s not pneumonia. Almost all kids will get a bout of it by age 2,” says Paul Checchia, M.D., an RSV specialist. RSV typically runs its course in five to seven days.

What to Do: Call your pediatrician right away if your little one seems to be struggling to breathe or is too irritable to eat or drink. Infants with bronchiolitis sometimes need to be hospitalized to receive oxygen treatment. If your child’s symptoms are mild (a wheezy cough without breathing trouble), blow his nose for him with a nasal aspirator or help him blow his nose, put a cool-mist humidifier in his room to help loosen mucus in his lungs, and make sure he drinks plenty of fluids. Kids can get RSV year after year because the body doesn’t build immunity to the virus. The virus can stay alive on surfaces for hours. “You can’t put your child in a bubble so the best you can do to avoid infection is wash your hands often,” Dr. Checchia says.