Bronchiolitis and Lower Respiratory Infections in Children

What is bronchiolitis?

Bronchiolitis is an infection of the airways that supply air to the lungs. It usually affects infants and children younger than age 2. Bronchiolitis develops when a virus in the nose and throat gets into the lungs. This leads to swelling in the smaller airways or bronchioles of the lung. This causes obstruction of air in the smaller airways.

Bronchiolitis is not the same as bronchitis. Bronchitis affects the larger tubes that lead into your lungs. Bronchiolitis is more serious because it is an infection of smaller tubes deeper in the lungs.


What causes bronchiolitis?

The most common cause of bronchiolitis is a virus, usually the respiratory syncytial virus (RSV). However, many other viruses have been involved, including:

  • Parainfluenza virus
  • Adenovirus
  • Influenza
  • Human metapneumovirus

Bronchiolitis is rarely caused by bacteria. If it is, the bacteria causing it is usually mycoplasma pneumoniae.

At first, the virus causes an infection in the upper respiratory tract, and then spreads downward into the lower tract. The virus causes inflammation and even death of the cells inside the respiratory tract. This leads to obstruction of airflow in and out of the child's lungs.

Facts about bronchiolitis

  • Bronchiolitis usually occurs in the winter and early spring.
  • Children ages 3 months to 6 months are the most common age group affected. But the condition can occur in children up to 24 months of age (2 years).
  • The following risk factors increase the likelihood that a child will develop bronchiolitis:
    • Having older children in the home
    • Attending day care
    • Not being breastfed as an infant
    • Exposure to smoke

What are the symptoms of bronchiolitis in babies?

A child with bronchiolitis will have a lot of mucus in their nose and lungs. While each child may experience different symptoms, the most common symptoms of bronchiolitis include:

  • Common cold symptoms, including a runny nose and congestion
  • Fever, which is a sign of the body fighting the infection
  • Harsh cough that often gets worse as the condition progresses because of the swelling of the breathing tubes 
  • Changes in breathing patterns (the child may breathe fast or hard; you may hear wheezing or a high-pitched sound)
  • Decreased appetite (infants may not eat well)
  • Fussiness
  • Vomiting, especially after coughing 

The symptoms of bronchiolitis may resemble other conditions or medical problems. Always consult your child's doctor for a diagnosis.

How is bronchiolitis diagnosed?

Bronchiolitis is usually diagnosed solely on history and a physical examination. Many tests may be done to rule out other diseases, such as pneumonia or asthma. In addition, the following tests may be ordered to help confirm the diagnosis:

  • Pulse oximetry. An oximeter is a small machine that measures the amount of oxygen in the blood. To get this measurement, we tape a small sensor (like a Band-Aid) onto a finger or toe. When the machine is on, a small red light shows on the sensor. The sensor is painless, and the red light does not get hot.
  • Nasopharyngeal swab. This test is for respiratory syncytial virus (RSV) and other respiratory viruses. These tests yield rapid results for presence of RSV or other viruses. This lets the care team know the appropriate infection precautions to take if the baby is admitted to the hospital.
  • Chest X-rays. This is an imaging test that uses invisible electromagnetic energy beams to look at the structures and organs in the chest.

How long does bronchiolitis last?

Bronchiolitis usually lasts several weeks. Symptoms usually get worse for the first three to five days as the infection moves from the nose into the lungs. It may be a gradual two weeks or longer until the infection is gone, and symptoms may go up and down. 

Treatment for bronchiolitis

Most cases of bronchiolitis are mild and you can treat symptoms at home. Bronchiolitis is caused by a virus, not a bacterial infection. For this reason, antibiotics are not effective at treating bronchiolitis.

Treatment for bronchiolitis involves supportive care with frequent nasal suctioning to clear mucus. It’s important to make sure your infant stays hydrated. You should also watch for signs that their illness is getting worse, based on their age, general health and medical history. Most babies will get better on their own and won’t need to see the doctor or go to the emergency room.

When should you call the doctor for your child’s respiratory infection?

You should call your pediatrician if:

  • Your child is extremely cranky or tired
  • Your child has trouble breathing that isn’t improving with suctioning
  • Your child is not drinking enough and not making a wet diaper every six to eight hours

You should also call your doctor if you just feel something isn’t right — trust your gut.

Typically, your pediatrician will recommend common at-home care such as:

  • Encouraging fluid intake
  • Frequent suctioning (with a bulb syringe) of your child's nose and mouth (to help get rid of thick secretions)
  • Giving acetaminophen (Children's or Infants' Tylenol) for fever if your child is uncomfortable. Do not give a child aspirin. There is a link between aspirin and Reye syndrome, a disease of the brain and liver.

Always consult your doctor for advice before giving a child younger than 6 years of age an over-the-counter (OTC) cold and cough medicine.

Some infants having severe breathing problems may need treatment in the hospital. While in the hospital, treatments your child may include:

  • Intravenous (IV) fluids if your child is unable to drink well
  • Oxygen therapy and a ventilator 
  • Frequent suctioning of your child's nose and mouth (to help get rid of thick secretions) 

Prevention of bronchiolitis

Consistent handwashing is one of the best ways to prevent bronchiolitis. Keep children home from school or daycare when they are sick to prevent illness from spreading. 

In the fall of 2023, the FDA approved a preventive monoclonal antibody medication called Beyfortus (or Nirsevimab). This medication protects babies from getting severe RSV, the most common cause of bronchiolitis.

The Centers for Disease Control and Prevention has guidance on who should get this preventative medication.

How does Beyfortus work?

Beyfortus is a single-dose “monoclonal antibody” given in one shot into the muscle, like a vaccine. It puts antibodies into the bloodstream that will help babies fight the virus, even while their immune system is still developing.

It provides an extra layer of defense against RSV and decreases the chances of getting very sick and landing in the hospital.

This medication prevents an infectious disease that impacts all children. For this reason, we’ve added it to the childhood immunization schedule for all CHOP Care Network patients.

Remember, respiratory infections and bronchiolitis in kids are very common. Most of the time, sick babies will need lots of extra tender loving care, but these infections will clear on their own after a few weeks.

Reviewed by Jane M. Lavelle, MD, Lori Handy, MD, MSCE , Kathleen Filograna, MD, FAAP

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