Croup in Babies and Toddlers

There is a moment in parenting — often around 2 AM — when your child starts coughing and the sound that comes out is unlike anything you have heard before. It is a harsh, barking cough that sounds like a seal, or a small dog, or something that definitely should not be coming from a toddler. If you have never heard croup before, it is genuinely alarming. Your instinct will be to grab your keys and drive to the emergency room.

Before you do, take a breath. In most cases, croup sounds much worse than it is. The bark is dramatic, but the vast majority of croup cases are mild and manageable at home. Understanding what is happening inside your child's airway helps you make the right call about when to stay home and when to go.

Croup is caused by a viral infection — most commonly parainfluenza virus — that causes swelling of the larynx (voice box) and trachea (windpipe). These are the upper airways, and in a small child, they are narrow to begin with. When the lining swells even a few millimeters, it significantly restricts airflow. The barking cough is the sound of air being forced through that narrowed space. Stridor — the high-pitched, raspy sound you may hear when your child breathes in — is another result of air squeezing through the swollen airway.

Croup is most common between six months and three years of age, with a peak around two years. It is more common in boys. It typically starts with one to two days of cold symptoms (runny nose, mild cough, low-grade fever) before the characteristic barking cough appears — often suddenly, often at night.

The key to managing croup is assessing severity, and the key to assessing severity is one symptom: stridor. Stridor is the high-pitched sound your child makes when breathing in (not out — that would be wheezing). It is caused by turbulent airflow through the narrowed upper airway.

Mild croup means your child has the barking cough but no stridor at rest. They may have stridor only when they are coughing, crying, or agitated — this is still considered mild because the airway is open enough for quiet breathing. Between episodes, the child is relatively comfortable. This is where most croup cases land, and it can be managed at home.

Moderate croup means stridor is present even when the child is calm and resting — you can hear the high-pitched sound just sitting next to them. There may be mild retractions (the skin between or below the ribs pulling in with each breath). The child may be more agitated than usual. This is the threshold for medical evaluation. Your child likely needs dexamethasone (a corticosteroid that reduces airway swelling).

Severe croup means loud stridor at rest, significant retractions, and a child who is either very agitated or, more worryingly, becoming lethargic. When a child with croup goes from agitated to lethargic, that is a sign of exhaustion — they are tiring out from the effort of breathing. This needs emergency treatment.

There is one counterintuitive thing to know: if stridor suddenly becomes quieter in a child who is clearly still struggling to breathe, that is actually worse, not better. It means the airway has become so narrow that there is not enough airflow to produce the sound. This is an emergency.

Croup loves the nighttime. The combination of cool air, lying down, pooling secretions, and naturally dropping cortisol levels means that croup episodes almost always peak between 10 PM and 4 AM. Your child may go to bed seeming fine — maybe a little congested — and wake up at midnight with a cough that sounds like a barking animal.

Here is what to do in the moment.

First, assess. Is there stridor? Listen carefully when your child is not actively coughing. Can you hear a high-pitched sound when they breathe in? If yes — and it persists even when they are not crying — this is moderate croup and warrants a trip to the ER. If stridor is only present during coughing or crying but disappears when they calm down, you are dealing with mild croup that can likely be managed at home.

Second, cool air. Pick your child up (upright position helps), and take them outside. If it is a cool or cold night, stand on the porch or take a short walk. Ten to fifteen minutes of cool air exposure reduces airway swelling in many children. If the weather is warm, sit in front of an open freezer or turn the air conditioning down. The goal is cool, moist air on the swollen airway.

Third, calm. Hold your child close, speak quietly, move slowly. Do not try to look down their throat. Do not do anything that will make them cry harder. A calm child breathes better. Put on a favorite show if it helps. Offer a small drink.

If symptoms improve with cool air and calming, you can return to bed — but plan to stay close. Croup can flare again the same night. If symptoms do not improve after fifteen to twenty minutes of cool air and calming, or if they worsen, head to the ER.

If you do end up at the emergency room for croup, here is what to expect. The process is usually straightforward and reassuring.

The doctor will assess your child's breathing — listening to the quality of the stridor, looking for retractions, checking oxygen levels, and observing how your child looks overall. They will likely give a single dose of dexamethasone (a corticosteroid), either by mouth or, if your child is vomiting, as an injection. Dexamethasone reduces airway inflammation and is the most effective treatment for croup. It starts working within two to four hours and its effects last two to three days. Many parents notice significant improvement by the time they get home or the next morning.

If croup is moderate to severe, nebulized racemic epinephrine may also be given through a face mask. Epinephrine works fast — within minutes — by constricting blood vessels in the swollen airway tissue, temporarily reducing the swelling. The catch is that it wears off in about two hours. This is why children who receive epinephrine are observed in the ER for two to four hours — the doctors need to make sure symptoms do not return when the epinephrine effect fades (this is called "rebound").

Antibiotics are NOT given for croup because it is a viral illness. Cough medicine is not used. The treatment is specifically aimed at reducing the airway swelling.

Most children go home the same night or morning. Hospitalization is reserved for severe cases that do not respond to treatment or for very young infants.

Not every barking cough is croup, and not every breathing difficulty in a toddler has the same cause. Here is how to think about the main possibilities.

Croup produces a distinctive barking cough with stridor (sound on inhalation). It develops gradually after cold symptoms and is classically worse at night. The child typically looks reasonably well between episodes. It responds to cool air and steroids.

Asthma causes wheezing — a whistling sound on exhale, not inhale. The cough is tight and wheezy, not barking. Asthma can be triggered by viral illness (just like croup can follow a cold), but it can also be triggered by allergens, exercise, or cold air. Asthma is less common in children under two but not impossible. It does not cause stridor.

Foreign body aspiration is the emergency to always consider, especially in the six-month to three-year age range when children put everything in their mouths. The hallmark is sudden onset — one moment the child is fine, the next they are choking, coughing, and struggling. There is no preceding cold, no fever, no gradual onset. If your child suddenly starts coughing with no warning, especially if they were playing with small objects or eating, think foreign body. This needs emergency evaluation.

Epiglottitis is rare since the Hib (Haemophilus influenzae type b) vaccine became standard, but it is the one to never miss. Epiglottitis is a bacterial infection of the epiglottis (the flap of tissue at the base of the tongue). It causes rapid-onset high fever, sore throat, drooling (because swallowing is too painful), a muffled voice, and stridor. The child looks toxic — visibly ill, often sitting in a "tripod" position (leaning forward, neck extended). This is a true emergency. If you suspect epiglottitis, go to the ER immediately and do NOT try to look down the child's throat — this can cause complete airway obstruction.

Your 18-month-old had a runny nose for two days — nothing dramatic, just daycare's weekly contribution to your household. You put him to bed at 7:30, and he goes down without fuss. At midnight, you are jolted awake by a sound you have never heard before. It sounds like there is a seal in the nursery. Your son is sitting up in his crib, barking out this alarming cough, and between coughs, you hear a high-pitched squeaky sound when he breathes in.

Your heart rate spikes. You pick him up and he clings to you, coughing. You listen: when he calms down on your shoulder, the squeaky sound disappears. It only comes back when he coughs or starts to cry. You remember reading that stridor at rest is the dividing line. No stridor when he is calm — that is mild croup.

You carry him to the front door, wrap a blanket around both of you, and step outside. It is 38 degrees Fahrenheit. You stand there, swaying slightly, talking to him in a low voice. Within ten minutes, the barking cough has softened. He coughs a few more times, but the bark is less dramatic. You go back inside, offer him a sippy cup of water, and he drinks. You sit in the rocking chair with him upright on your chest. He falls asleep. You do not. You log a quick note in tinylog — "midnight croup episode, stridor only when crying, cool air helped, settled by 12:30" — and sit in the chair for the rest of the night.

The next morning, he seems fine. Runny nose, a mild regular cough, but no barking. You call the pediatrician's office and report what happened. They say: mild croup, expect it to return tonight, call if stridor is present at rest. It does return — the second night is actually a little worse, with more frequent barking episodes. But each time, cool air and calm settle him. By night four, it is over.

• RSV in Babies — Another respiratory illness to know about
• Baby Breathing Fast — When it is normal and when it is a red flag
• Baby's First Cold — What to do when it happens

• Smith, D. K., et al. (2018). Croup: Diagnosis and Management. American Family Physician, 97(9), 575-580.
• Bjornson, C. L., & Johnson, D. W. (2013). Croup in Children. Canadian Medical Association Journal, 185(15), 1317-1323.
• Petrocheilou, A., et al. (2014). Viral Croup: Diagnosis and a Treatment Algorithm. Pediatric Pulmonology, 49(5), 421-429.
• American Academy of Pediatrics (AAP). (2024). Croup and Your Young Child. HealthyChildren.org.
• Gates, A., et al. (2018). Glucocorticoids for Croup in Children. Cochrane Database of Systematic Reviews.
• Cherry, J. D. (2008). Croup. New England Journal of Medicine, 358(4), 384-391.

This guide is for informational purposes only and is NOT a substitute for professional medical advice. When in doubt, always call your pediatrician. If your baby is under 3 months with a fever, having difficulty breathing, showing signs of dehydration, or seems seriously unwell, seek immediate medical attention.