Is Croup Cough Contagious? Can Adults Get Croup?

Croup is an upper respiratory infection typically caused by a viral infection called HPIV, or human parainfluenza virus. Respiratory syncytial virus is another common cause of croup. Viral croup obstructs breathing because of “swelling around the voice box (larynx), windpipe (trachea), and bronchial tubes,” according to The Mayo Clinic.). Such swelling is in the upper airway and can affect breathing in children, resulting in the characteristic “barking” cough and stridor, also known as “croup cough sounds.” This cough is often described as having a seal barking quality, and children may also develop a hoarse voice.

The Boston Children’s Hospital says these viral infections are primarily seen in infants and children ranging in age from three months to five years old. However, croup can also affect older children, though it is less common in this age group.

Croup is most often caused by a viral infection, with human parainfluenza viruses being the leading culprits. These viruses are easily spread from person to person through respiratory droplets released when someone coughs or sneezes, or by touching surfaces contaminated with the virus. Once the virus enters the body, it causes inflammation and swelling in the upper airway, particularly around the voice box (larynx) and windpipe (trachea). This swelling is what leads to the hallmark symptoms of croup, such as the distinctive barking cough and trouble breathing. While viral infections are the most common cause, croup can occasionally result from a bacterial infection or other triggers like allergies or acid reflux. Regardless of the cause, the swelling in the upper airway is what makes croup symptoms so noticeable and sometimes concerning.

The signs and symptoms of croup usually begin with common symptoms such as a fever, runny nose, and cough, which can progress to more distinctive features as the illness develops.

Common symptoms of croup include:

• Loud, harsh cough (often described as a “barky cough”)

• A raspy vibrating, high pitched sound when breathing called stridor

• Trouble breathing

• Runny nose

Stridor is a high pitched sound that occurs during breathing due to airway narrowing.

Croup is typically mild in its initial stages, but it is important to monitor your child’s symptoms closely, as they can worsen quickly and require prompt medical attention. Mild croup often presents with a barking cough and hoarseness and can usually be managed at home, while moderate croup involves more noticeable breathing difficulties and may need medical evaluation. Most cases are mild and clear up within 48 hours, but the severity can increase, so watch for any changes in your child’s symptoms.

The cough associated with croup is very distinct, as it produces a husky, seal-like sound. The sound is made due to the swollen vocal cords.

Croup is contagious, especially during the first few days or while your child has a fever. A child is considered contagious for about three days after symptoms begin or until the fever resolves. The Cleveland Clinic confirms that “croup can be spread by physical contact or through the air.”

How long does croup last? Most cases improve within three to five days, but the cough may linger for up to a week. The contagious period typically overlaps with the first few days of illness.

To prevent the spread, best practices include:

• Thoroughly washing your hands, as well as your child’s

• Encouraging your child to cover their coughs and sneezes with their elbow or a tissue

• Disinfecting toys and high-touch surfaces

• Keeping your child away from others who are sick

• For nighttime monitoring, parents should sleep in the same room as their child to watch for any breathing difficulties 

The length of time croup lasts can vary from child to child, but most cases resolve within 3 to 7 days. Typically, the most severe symptoms—such as the barking cough and trouble breathing—peak on the second or third night of illness. While many children start to feel better after a few days, the distinctive cough can sometimes linger for up to a month, even after other symptoms have improved. It’s important to keep a close eye on your child’s symptoms, especially if they develop more severe symptoms like difficulty breathing. If you notice your child’s condition worsening or lasting longer than expected, don’t hesitate to seek medical attention.

While most cases of croup are mild and resolve with home treatment, severe croup can lead to serious complications. Significant swelling in the airway can make it very difficult for a child to breathe, and in rare cases, this can become a life-threatening condition. Children with severe croup may need to be hospitalized for treatments that help reduce airway swelling, such as oxygen therapy or steroids. Other potential complications include pneumonia or, very rarely, respiratory failure. It’s crucial to seek immediate medical attention if your child shows any of the following symptoms: severe difficulty breathing, a high-pitched whistling sound (stridor) when inhaling, blue lips or face, or a high fever over 104°F (40°C). Prompt care can help prevent more serious outcomes and ensure your child’s safety.

Some children experience recurrent croup, which means they have more than two episodes of croup within a single year. Recurrent croup can be more challenging to manage and may be linked to underlying conditions, such as a naturally narrow airway or a history of intubation. If your child has recurrent croup, it’s important to work closely with their healthcare provider to identify any contributing factors and develop an effective treatment plan. In certain cases, your child may be referred to a specialist, such as an otolaryngologist or pulmonologist, to further investigate the cause of their symptoms and ensure the best possible care.

Preventing croup starts with reducing your child’s risk of catching viral infections and limiting the spread of germs. Encourage frequent handwashing and teach your child to cover their mouth and nose when coughing or sneezing to help prevent croup and other respiratory illnesses. If your child is showing symptoms of croup or another respiratory illness, keep them home from school or daycare to avoid spreading the infection to others. Avoid sharing cups, utensils, or personal items that can transmit respiratory droplets. Using a cool mist humidifier in your child’s room can help keep the air moist, which may reduce inflammation and make breathing easier. If you’re caring for a child with croup, consider wearing a mask to lower your own risk of infection. Keeping your child up to date on recommended vaccinations, including the flu shot, can also help prevent croup and other common respiratory illnesses. By following these steps, you can help protect your child and others from developing croup and its symptoms.

If your little one’s symptoms persist or worsen after three to five days, you should take them to the doctor. According to the American Family Physician, severe cases of croup may require breathing treatments, prescription medication, or in more rare cases, hospitalization. If your child experiences severe symptoms such as difficulty breathing, blue or gray skin around the nose, mouth, or fingernails (cyanosis), or is unable to breathe due to airway swelling, take them to the emergency room immediately.

Severe cases may be characterized by:

• Wheezing or high-pitched noises when breathing or crying

• Difficulty swallowing

• Breathing at a faster rate than normal

• The inability to breathe due to the airway swelling

• Blue or gray skin around the nose, mouth, or fingernails (cyanosis)