What's normal: At least one bout of croup by age 3.
What's not: When breathing becomes a serious struggle for your child.
Why your child may be vulnerable: Up to half of all kids who've had one episode of croup -- a viral infection that leads to swollen airways, a scary-sounding "barking cough," and late-night home treatments in a steamy bathroom or outdoors in the cold air -- will go through it again, researchers estimate.
Why? Reasons range from physical anatomy and gender to race, genetics, and prematurity. Experts aren't sure why, but croup rates are 43 percent higher in boys than in girls, and 85 percent lower in African-American children than in Caucasian kids. A better-understood risk: being born with a narrower-than-usual voice box (larynx) and windpipe (trachea). The tiniest portion of the windpipe, the subglottal trachea, swells during croup.
Pediatricians are also realizing that the breathing tubes that premature infants often require may scar the delicate lining of the trachea, leading to more croup as they grow. Asthma and a family history of allergies also heighten a child's risk.
For some kids, a recurrent croupy cough isn't even prompted by a viral infection: Muscle spasms start the process.
Advice for parents: Skip the cough syrup, since it won't reach the larynx or trachea. And never try to open your child's airways with your finger. The best home treatment? Time in a steamy bathroom (turn on the shower). Or if that doesn't work, try moist, cold air. Call your pediatrician -- or 911 -- if your child's breathing worries you.