Croup: The Barking Cough, Symptoms, Causes, Home Care and When to Go to the ER — What Parents Need to Know
Updated: 2 days ago
Medically reviewed by Dr. Baraa Alnahhal, MD · Last reviewed: September 2026
Quick Answer
Croup is a very contagious respiratory infection that mostly affects babies and young children under age 3. It causes swelling of the voice box (larynx) and windpipe (trachea), producing a harsh barking cough, a raspy breathing sound called stridor, and sometimes fever and hoarseness. Most cases are mild and clear up within two days, lasting no more than a week. Mild croup can usually be treated at home with mist from a humidifier or steamy bathroom, cool night air, fever medicine such as acetaminophen or ibuprofen, warm fluids, and smoke-free air. Severe croup is life-threatening — go to the emergency room right away if your child struggles to breathe, has blue-tinged skin, drools, cannot cry or speak, or sucks in the skin around the ribs and breastbone.
TL;DR
Croup is a common viral respiratory illness of babies and toddlers that causes the airway below the vocal cords to swell, leading to a distinctive seal-like barking cough and raspy breathing when breathing in. According to the source data, croup affects about 3% of U.S. children each year, accounts for 7% of all hospitalizations in children under 5, and about 85% of cases are mild while less than 1% are severe. Most children improve within two days with simple home care, though symptoms can last up to a week and occasionally worsen quickly.
Limitation statement: All statistics above come directly from the referenced medical source, which describes U.S. children broadly. The source does not break these figures down by age range within the under-3 group, by season, or by region, and it provides no specific complication or mortality rates, so those figures are not quoted here.
What is croup, exactly?
Croup — medically called laryngotracheobronchitis — is a respiratory infection that affects young children. Viral infections are the most common cause of the condition.
Croup causes swelling of your child's voice box (larynx) and windpipe (trachea). This swelling narrows the airway below the vocal cords, which makes breathing noisy and difficult.
Croup in babies is most common, along with children younger than 3 years old. As children get older, croup isn't seen as often. This is because their windpipes get larger and swelling is less likely to get in the way of their breathing.
Croup causes a distinctive cough that may sound similar to the call of a seal. The condition is usually mild, but symptoms can become severe and life-threatening.
Quick fact | What the source says |
What it is | A respiratory infection (laryngotracheobronchitis) |
Who gets it | Babies and children under 3, most often; can rarely affect adults |
What it does | Swells the larynx and trachea, narrowing the airway below the vocal cords |
Signature symptom | A harsh barking cough; raspy breathing in (stridor) |
How long it lasts | Usually clears within two days; can persist up to one week |
Typical severity | About 85% of cases are mild; less than 1% are severe |
Why does croup cause a barking cough?
The barking sound comes from the swelling itself. When the airway below the vocal cords narrows, air passing through the swollen larynx produces a harsh, seal-like sound instead of a normal cough.
Your child may also have stridor, which is a raspy, vibrating sound that occurs when your child is breathing in.
The croup cough is the most common symptom of croup, and it is the feature most parents learn to recognize first.
What are the symptoms of croup?
Croup is typically mild and lasts less than one week, but symptoms can get more severe. Symptoms normally start slowly and may begin with a runny or stuffy nose. Over the next 12 to 48 hours, symptoms can worsen and the barking cough may start. Symptoms are usually worse at night.
Other mild croup symptoms include hoarseness, fever, rash, eye redness (conjunctivitis), and swollen lymph nodes.
Symptoms of moderate to severe croup may include difficulty breathing, restlessness or nervousness, retractions (sucking in the skin around your child's ribs and the top of their breastbone), and cyanosis (blue-tinged skin).
Severity level | What your child may show | What to do |
Mild | Barking cough and stridor; symptoms can worsen through the illness, especially in the evening | Usually treat at home; watch breathing closely |
Moderate | Stridor plus retractions; slightly agitated or disoriented; moderate trouble breathing | Take your child to see a healthcare provider for treatment |
Severe | Stridor and retractions; agitated, anxious, or fatigued; blue-tinged skin (cyanosis) common | Life-threatening — take your child to the emergency room immediately |
When should I take my child to the ER?
Severe croup can be life-threatening, and you shouldn't delay. If your child develops symptoms of severe or worsening croup, seek immediate medical attention. Go to the emergency room if your child has any of the following:
Difficulty breathing
Blue-tinged skin (cyanosis)
Severe coughing spells
Drooling or difficulty swallowing
Inability to cry or speak due to trouble taking a breath
A noisy, high-pitched whistling sound while breathing
Sucking in the skin around the ribs and the top of the breastbone (retractions)
What causes croup, and how do children catch it?
The most common cause of croup is a viral infection. Croup viruses include parainfluenza, influenza, respiratory syncytial virus (RSV), measles, and adenovirus.
Viral croup causes your child's upper airways to swell, making it difficult for them to breathe. However, these viruses are common, and most children with viral infections don't develop croup. Rarely, bacteria can complicate the viral infection and make it more difficult to breathe.
Yes, croup is highly contagious because the viruses that lead to the condition are easily spreadable.
The viruses that cause croup spread easily through the air. When someone with a viral or bacterial infection that can cause croup sneezes or coughs, they send respiratory droplets containing croup-causing germs into the air. When your child breathes in these droplets, they can catch an illness that'll cause croup. Your child can also get croup by touching objects contaminated by germs that can cause croup.
Your child is contagious for three days after their symptoms first appeared or until their fever is gone. You should keep your child home from school until 24 hours have passed without a fever and without using fever-reducing medication.
Croup is especially widespread in the fall and winter months.
RSV vs. croup — what's the difference?
RSV (respiratory syncytial virus) and croup are both respiratory illnesses that can affect babies and young children. RSV is a viral infection that can affect both children and adults. It causes coughing, sneezing, and other cold-like symptoms.
While RSV is its own illness, the respiratory syncytial virus is also one of the viruses that can lead to croup.
Whooping cough vs. croup — what's the difference?
Whooping cough (pertussis) and croup are both respiratory infections that can affect babies and children. Both conditions cause a distinctive cough, although the sound of whooping cough is a more high-pitched gasping or "whooping" noise.
Whooping cough is a bacterial infection, whereas a viral infection usually causes croup. Therefore, no vaccines can prevent croup, and antibiotics can't treat it (antibiotics can't kill viruses). There's a vaccine to prevent whooping cough, but it doesn't go away quickly on its own as croup usually does.
How common is croup?
Croup affects about 3% of U.S. children every year. The condition accounts for 7% of all hospitalizations in children younger than 5 years old. It's more common in males. Healthcare providers define about 85% of croup cases as mild. They consider less than 1% of cases severe.
Because babies' and toddlers' windpipes are narrower and not fully developed, swelling is more likely to affect their breathing. Adults have larger airways, so croup doesn't typically affect them — and when adults do get croup, their symptoms are usually worse and they may need more aggressive treatment.
How is croup diagnosed?
You can usually tell if your child has croup based on their signs and symptoms. The most common symptoms are a barking cough and stridor.
If your child's condition is severe, a healthcare provider may order X-rays and laboratory tests, but this is rare.
How is croup treated at home?
Croup treatment depends on the severity of your child's condition and the risk of it rapidly worsening. If your child has a history of respiratory problems or was born prematurely, that may also affect the treatment approach.
You can usually treat mild croup at home. Home treatment includes using a cool mist humidifier to help soothe dry and irritated airways. You can also sit with your child in a bathroom filled with steam generated from hot water running in the shower. (Don't sit in the shower or let your child near the hot water.) If your child's condition doesn't improve with mist treatment, you should contact their healthcare provider.
Other croup home remedies include letting your child breathe cool air at night by opening a door or window, treating fever with an over-the-counter medication such as acetaminophen (Tylenol®) or ibuprofen (Advil®), and treating the cough with warm, clear fluids to help loosen the mucus on their vocal cords.
Avoid smoking in your home, as smoke can worsen your child's cough. Keep your child's head elevated with an extra pillow — but don't use pillows with infants younger than 12 months old.
You may wish to sleep in the same room as your child so you're there if they start to have trouble breathing.
Home care step | What to do | Safety note |
Moist air | Cool mist humidifier; steamy bathroom from hot shower water | Don't sit in the shower or let your child near hot water |
Cool air | Open a door or window at night | — |
Fever | Acetaminophen or ibuprofen (OTC) | Follow age-appropriate dosing |
Cough | Warm, clear fluids | Loosens mucus on vocal cords |
Air quality | No smoking in the home | Smoke worsens the cough |
Position | Head elevated with an extra pillow | Never with infants under 12 months |
Monitoring | Consider sleeping in the same room | So you're there if breathing trouble starts |
How is moderate or severe croup treated?
For moderate to severe croup, you should take your child to the nearest urgent care center or emergency room (ER). Severe croup can be life-threatening, and you shouldn't delay taking your child in. Treatment for moderate to severe croup will vary based on your child's symptoms.
Croup treatments may include humidified air or oxygen, IV fluids for dehydration, and monitoring of vital signs including oxygen levels, breathing, and heart rate.
Medication may include steroids (glucocorticoids) and nebulized breathing treatments (epinephrine). Placement of a breathing tube (mechanical ventilation) is rare.
If you take your child to their provider's office or the emergency room, their provider will give them a glucocorticoid and a nebulized breathing treatment (epinephrine).
Glucocorticoids are a type of steroid that decreases the swelling of your child's voice box, typically within six hours of the first dose. For a child with mild croup, glucocorticoids may reduce the need for a repeat visit to their provider's office or the emergency room. The glucocorticoids healthcare providers use most often are dexamethasone and prednisolone. Your child will usually only need one dose taken by mouth. If your child is vomiting or can't keep the medicine down, their provider can also give dexamethasone intravenously (IV) or through an intramuscular (IM) injection.
Nebulized epinephrine is given as an inhaled mist (nebulizer). This also reduces the swelling in your child's airways and usually starts working within 10 minutes. Epinephrine works for two hours or less, and your child may receive this treatment every 15 to 20 minutes for severe symptoms.
Serious side effects of epinephrine are rare. However, side effects could include a rapid heartbeat (tachycardia). A healthcare provider will monitor your child for three to four hours after their last dose to ensure symptoms of airway blockage don't return.
Glucocorticoids usually start working within six hours of the first dose. Epinephrine typically begins working faster than glucocorticoids.
How long does croup last?
Symptoms of croup usually clear up in most children within two days. However, symptoms can persist for up to one week.
Your child should stay home from school until after their fever is gone, because croup is very contagious.
What are the complications of croup?
Most cases of croup are mild and you can treat them at home. Complications of croup are rare. Less than 5% of children with croup need in-hospital care.
Your child's condition may lead to hospitalization if they need oxygen therapy to keep their oxygen levels within a safe range, have severe dehydration that requires IV (intravenous) fluids, need multiple doses of inhaled breathing treatments to provide relief, or have severe symptoms despite initial treatment.
Why does my child keep getting croup?
If your child keeps getting croup, it may be a sign they have a narrowing in their airway and that they're at a higher likelihood to be affected by the infection. Your child may have been born with the narrowing or it may have developed after birth.
If croup returns (recurs) repeatedly, your child's provider may refer them to a specialist such as an otolaryngologist (ear, nose and throat doctor) or a pulmonologist (breathing and lung disease doctor).
When should I call my child's healthcare provider?
You should call your child's healthcare provider if your child has a fever that lasts for more than three days, if your child has symptoms of mild croup that last for more than one week, or if you have questions or are concerned about your child's condition.
How can the spread of croup be prevented?
Croup can spread by physical contact or through the air. To help prevent its spread, wash and dry your hands thoroughly after caring for your child, wash toys between each use, encourage your child to cover their mouth and nose when coughing and sneezing, keep your child home from school or daycare when they're ill or if outbreaks occur, and throw used tissues away.
What to expect: a quick guide for parents
A note from the referenced medical source: "Croup is a very contagious respiratory infection that affects babies and young children. You'll know it's croup because of the distinctive barking cough your child develops. While most cases of croup are mild, the condition can worsen quickly, become severe and prevent your child from breathing properly. If your child's croup isn't improving, contact their healthcare provider for evaluation and treatment."
Most cases of croup follow a reassuring pattern: a runny nose starts it off, the barking cough arrives over the next day or two, the worst breathing usually happens at night, and most children are better within two days. Because symptoms are typically worst at night, close monitoring and calm presence make a real difference.
The important exceptions are the warning signs: difficulty breathing, blue-tinged skin, severe coughing spells, drooling, inability to cry or speak, a high-pitched whistling sound, or retractions. Any of these means the emergency room, without delay.
Conclusion
Croup is one of the most recognizable childhood illnesses — the barking cough that sounds like a seal is hard to forget once you've heard it. It is very contagious, peaks in fall and winter, and mostly affects babies and children under 3 because their windpipes are narrow. The good news: about 85% of cases are mild, most children recover within two days, and simple home care — mist, cool air, fever medicine, warm fluids, and smoke-free air — is usually all that's needed.
The watch-outs matter more than the illness itself. Croup can worsen quickly, and severe croup is life-threatening. Keep the emergency signs in this article visible — ideally printed and on the fridge — so that every caregiver knows when mist and patience are enough and when the ER is non-negotiable.
Call to action: If your child has a barking cough or raspy breathing, start with the home-care steps above and watch their breathing closely. If anything feels off — and your instinct is usually right — contact your pediatrician. If your child struggles to breathe, has blue-tinged skin, drools, or can't cry or speak, go to the nearest emergency room immediately. Trust your instincts; parents know their children best.
FAQ
What is croup?
Croup (laryngotracheobronchitis) is a respiratory infection that affects young children. It causes swelling of the voice box (larynx) and windpipe (trachea), narrowing the airway below the vocal cords and making breathing noisy and difficult. Viral infections are the most common cause.
What does croup sound like?
The croup cough sounds like a harsh "barking" sound — often compared to a seal's call. Children may also have stridor, a raspy, vibrating sound when breathing in.
What causes croup?
A viral infection is the most common cause. Croup viruses include parainfluenza, influenza, respiratory syncytial virus (RSV), measles, and adenovirus. Rarely, bacteria can complicate the viral infection.
Why do toddlers get croup more than older children?
Babies and children under 3 have narrower windpipes that aren't fully developed, so swelling is more likely to affect breathing. As windpipes grow larger with age, swelling is less likely to get in the way of breathing.
Is croup contagious?
Yes, croup is highly contagious because the viruses that lead to the condition are easily spreadable through the air and by touching contaminated objects.
How long is croup contagious?
Your child is contagious for three days after symptoms first appear or until the fever is gone. Keep your child home from school until 24 hours pass without a fever and without using fever-reducing medication.
How long does croup last?
Symptoms usually clear up within two days for most children but can persist for up to one week. Symptoms are typically worse at night.
How common is croup?
Croup affects about 3% of U.S. children every year and accounts for 7% of all hospitalizations in children younger than 5. About 85% of cases are mild, and less than 1% are severe. It's more common in males.
Is croup dangerous?
Croup is usually mild, but symptoms can become severe and life-threatening. Severe croup requires an immediate ER visit. Less than 5% of children with croup need in-hospital care.
When should I go to the ER for croup?
Go immediately if your child has difficulty breathing, blue-tinged skin (cyanosis), severe coughing spells, drooling or difficulty swallowing, inability to cry or speak, a noisy high-pitched whistling sound while breathing, or retractions (sucking in of the skin around the ribs and breastbone).
Can I treat croup at home?
Yes — mild croup can usually be treated at home with a cool mist humidifier, steamy bathroom air, cool night air, OTC fever medicine (acetaminophen or ibuprofen), warm clear fluids, no smoking in the home, and an elevated head (never pillows for infants under 12 months).
What is the steamy bathroom trick for croup?
Sit with your child in a bathroom filled with steam generated from hot water running in the shower. The mist helps soothe dry, irritated airways. Don't sit in the shower or let your child near the hot water.
Why is croup worse at night?
Symptoms usually start slowly (often with a runny or stuffy nose) and worsen over the next 12 to 48 hours, with the barking cough starting and symptoms typically worse at night.
What medications treat croup?
Providers give a glucocorticoid (usually oral dexamethasone or prednisolone, sometimes IV or IM) and a nebulized epinephrine breathing treatment. Glucocorticoids reduce swelling within about six hours; epinephrine works within about 10 minutes but lasts two hours or less.
Are there side effects from croup medication?
Serious epinephrine side effects are rare but could include rapid heartbeat (tachycardia). Providers monitor children for three to four hours after the last dose to ensure airway blockage symptoms don't return.
Does croup need antibiotics?
No. Croup is usually viral, and antibiotics can't kill viruses. No vaccines can prevent croup either.
What's the difference between croup and RSV?
RSV is its own viral illness affecting children and adults with cold-like symptoms. The respiratory syncytial virus is also one of the viruses that can lead to croup.
What's the difference between croup and whooping cough?
Whooping cough (pertussis) is bacterial with a high-pitched "whooping" gasp; croup is usually viral with a barking cough. A vaccine prevents whooping cough, but no vaccine prevents croup.
Can adults get croup?
Yes, but it's rare. Adults have larger airways. When adults do get croup, symptoms are usually worse and may need more aggressive treatment.
Why does my child keep getting croup?
Recurrent croup may signal a narrowing in the airway — present from birth or developed afterward. Providers may refer to an otolaryngologist (ENT) or pulmonologist.
When should I call my child's doctor about croup?
Call if your child has a fever lasting more than three days, mild croup symptoms lasting more than one week, or if you have any questions or concerns.
Can croup lead to hospitalization?
Yes, though less than 5% of children with croup need in-hospital care — for oxygen therapy, IV fluids for severe dehydration, multiple doses of inhaled breathing treatments, or severe symptoms despite initial treatment.
How can I prevent the spread of croup?
Wash and dry hands thoroughly after caring for your child, wash toys between uses, cover the mouth and nose when coughing or sneezing, keep your child home when ill or during outbreaks, and throw used tissues away.
When can my child go back to school after croup?
Your child should stay home from school until after their fever is gone, because croup is very contagious.
What does stridor mean?
Stridor is a raspy, vibrating sound that occurs when your child is breathing in. It is a hallmark symptom of croup, along with the barking cough.
External References
Source article (medically reviewed): https://my.clevelandclinic.org/health/diseases/8277-croup
Original page references (accessed 5/3/2023): American Academy of Family Physicians — Croup; American Academy of Pediatrics — Croup and Your Young Child; American Family Physician — Croup: What You Should Know; CDC — Human Parainfluenza Viruses (HPIVs); Merck Manual Consumer Version — Croup; NHS (U.K.) — Croup; StatPearls (NCBI) — Croup
Additional authoritative references to cite: https://www.cdc.gov/parainfluenza/about/index.html (CDC on parainfluenza), https://www.nhs.uk/conditions/croup/ (NHS croup guide), https://www.healthychildren.org/English/health-issues/conditions/chest-lungs/Pages/Croup-Treatment.aspx (AAP on croup treatment), and https://www.ncbi.nlm.nih.gov/books/NBK431070/ (StatPearls clinical review).
Medical Disclaimer
This article is for general informational purposes only and is based on the referenced medical sources. It is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of a qualified healthcare provider with any questions about your child's health. Never disregard or delay professional medical advice because of something you have read here. If you think your child may have a medical emergency, go to the nearest emergency room or call your local emergency number immediately.
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