Medically Reviewed By William C. Lloyd III, MD, FACS
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What is bronchiolitis?

Bronchiolitis is an infection that affects the bronchioles, tiny airways inside the lungs that make up the lower part of the respiratory tract. Infection in the bronchioles causes inflammation and swelling, which can cause a blockage that makes it hard for air to pass in and out of the lungs.

Bronchiolitis infections are usually caused by viruses, although in exceptional cases, they can be caused by bacteria. The infection usually affects babies and young children, and most often during the winter and early spring. Bronchiolitis is one of the primary drivers behind infant hospitalizations in the United States, with an estimated 100,000 hospital admissions per year.

Viral infections that can lead to bronchiolitis include common cold viruses, flu virus (influenza), and respiratory syncytial virus (RSV). Early symptoms of these viral infections resemble a cold, and may include a runny and/or stuffy nose, cough, and fever. With bronchiolitis, the infection moves from the upper airway down to the bronchioles. Bronchiolitis symptoms may include fever, cough, runny nose/stuffy nose, irritability, poor appetite, and breathing problems, such as wheezing.

The duration of the infection among children varies, lasting from a few days to a few weeks. In consultation with a pediatrician, parents can manage most cases of bronchiolitis at home; but, if the child starts to have trouble breathing, emergency medical care is necessary. Go to your nearest emergency department or call 911.

For adults, bronchiolitis is a chronic, progressive disease called bronchiolitis obliterans. Oftentimes, it is caused by internal and external environmental exposures, including smoking. Treatments include medication, respiratory therapy, supplemental oxygen, and lung transplant.

What are the different types of bronchiolitis?

There are two main types of bronchiolitis:

  • Viral bronchiolitis is the type that affects children and is caused by viral respiratory infections. It is the most common type of bronchiolitis.
  • Bronchiolitis obliterans, sometimes called constrictive bronchiolitis, is a rare type of bronchiolitis that affects adults.

What are the symptoms of bronchiolitis?

Initially, bronchiolitis symptoms resemble those of a common cold. But with bronchiolitis, the symptoms continue or get worse while cold symptoms go away within a week or two.

Common symptoms of viral bronchiolitis 

The most common symptoms of viral bronchiolitis are:

  • Coughing
  • Stuffy nose

While not common, some children with bronchiolitis develop a fever too.

Common symptoms of bronchiolitis obliterans

Bronchiolitis obliterans is a constrictive type of bronchiolitis that develops in adults. Common bronchiolitis obliterans symptoms include:

  • Wheezing

These are most often triggered on exertion and can occur early after exposure to a lung irritant (such as breathing in a toxic substance) or months or years later.

Serious symptoms that might indicate a life-threatening condition

In some cases, bronchiolitis can be life-threatening. Seek immediate medical care (call 911) if you, or someone you are with, have any of these life-threatening symptoms including:

  • Audible wheezing (high-pitched sound when exhaling)
  • Change in skin color (pale, blue tinted lips or fingernail beds, due to lack of freshly oxygenated blood)
  • Nostrils flaring with each breath
  • Shallow, fast breathing

In cases of babies and young children, other serious signs to watch for include:

  • Decrease in urine output (fewer soiled diapers, for example)
  • Inability to feed due to fast breathing
  • Increase in fussiness
  • Lethargic or difficult to stimulate
  • Not waking for feedings

What causes bronchiolitis?

Bronchiolitis causes differ by age.

Respiratory syncytial virus (RSV) infection is the main cause of bronchiolitis in a child, although other respiratory viruses, such as a common cold or flu virus can cause it too. Bronchiolitis itself is not contagious, but the virus that caused it is. In other words, a child with bronchiolitis could spread the virus to another child, who may develop an upper respiratory infection but not necessarily the complication of bronchiolitis.

Rarely, bronchiolitis is bacterial, caused by Mycoplasma pneumoniae or Chlamydia pneumoniae.

Bronchiolitis in an adult is bronchiolitis obliterans, usually the result of lung damage caused by breathing in irritant fumes over time. Some people call it “popcorn lung” because it was first identified among workers who worked in a popcorn plant. Some of the toxic substances that can cause bronchiolitis obliterans include:

  • Acetaldehyde, which can be found in cannabis and e-cigarette smoke
  • Ammonia
  • Diacetyl, used to flavor e-cigarettes and other consumables like microwave popcorn
  • Formaldehyde, found in building materials, glues and many other household products
  • Hydrochloric acid, used in the steel industry, as well as making batteries and other products
  • Mustard gas
  • Nicotine
  • Nitrogen oxides, produced when burning fossil fuels

People who have been exposed to those irritants should speak with their doctor if they begin experiencing any breathing problems or other signs of bronchiolitis.

Bronchiolitis obliterans is also a complication for some people after receiving a lung transplant.

What are the risk factors for bronchiolitis?

The risk factors associated with developing bronchiolitis depends on the type—viral or bronchiolitis obliterans. Not all people with risk factors will get bronchiolitis. The most common risk factors for viral bronchiolitis include:

  • Being less than 2 years old. The risk is even greater for infants younger than 3 months.
  • Being born preterm (before 37 weeks gestation)
  • Attending daycare or other environments where there are multiple people who could spread a virus
  • Having siblings who could contract a virus from school or elsewhere
  • Being exclusively bottle-fed with formula
  • Living where there is exposure to tobacco smoke

Risk factors for bronchiolitis obliterans include:

  • Being a lung transplant recipient
  • Having an autoimmune disease
  • Working in an environment with chemical irritant exposure

Reducing your risk of bronchiolitis

You may be able to lower your child’s risk of viral bronchiolitis by:

  • Avoiding contact with people who have a respiratory virus, including a cold
  • Breastfeeding when possible or using breast milk in a bottle
  • Infection prevention, including frequent and thorough hand washing, cleaning all surfaces, particularly toys that might be shared between children
  • Not smoking
  • Speaking to your child’s doctor about vaccination against RSV

To lower the risk of developing bronchiolitis obliterans:

  • Avoid toxic substances in the air and wear appropriate face masks to prevent breathing in the toxic substances
  • Do not smoke cigarettes or e-cigarettes and avoid secondhand smoke

How do doctors diagnose bronchiolitis?

When children have bronchiolitis, doctors can usually make the diagnosis by the baby’s physical signs and symptoms alone. However, if there is a reason to believe that the symptoms may be signs of another illness, a doctor may order:

  • Blood tests
  • Swab of mucus to test for a viral cause, such as respiratory syncytial virus or influenza virus

Diagnosis of bronchiolitis obliterans usually involves tests such as:

  • Chest X-rays
  • Mucus swab
  • Pulmonary function tests, which measure issues like how much air capacity a person has. PFTs include tests like spirometry, pressure volume study, and lung diffusion capacity testing, among others.

What are the treatments for bronchiolitis?

Although viral bronchiolitis can last up to two or three weeks, it generally does not require medical treatment. The body’s immune system will clear the virus and inflammation will go away with time. Instead, at-home care of the symptoms helps the child feel more comfortable.

At-home treatments and therapies for bronchiolitis in babies and children include:

  • For fever, try over-the-counter medications like acetaminophen, which can help bring down a fever. Do not give aspirin as it could cause a rare but serious condition called Reye's syndrome when given to children with a viral infection
  • Keep your child well hydrated with extra fluids. Ask your child’s pediatrician what type of fluid is best. Your child may prefer water or an oral hydration solution to breast milk, formula, or dairy milk.
  • Position the crib or bed so the head is elevated to help drain the mucus from the nasal passages and sinuses.
  • Remove excess mucus, if necessary, using a bulb syringe or apply saline nose drops.
  • Set up a humidifier to add moisture to the air, which can make it more comfortable to breathe. Be sure to clean the humidifier according to the package directions.

There are some medicines a doctor may prescribe if the child becomes seriously ill. Although antibiotics do not work for viral illnesses, a doctor will prescribe them if there is a risk of secondary bacterial infection in the lungs. Other drugs, such as corticosteroids (like prednisone) or inhaled drugs that open the airway, have not been shown to help treat bronchiolitis.

In case of a hospitalization, the child may require oxygen by mask to help with breathing and intravenous (IV) fluids for hydration. A nurse or respiratory therapist may have to suction the mucus from the child’s mouth and nose, as well.

If you smoke, do not smoke in the home or around the child.

Bronchiolitis obliterans

There is no cure for bronchiolitis obliterans. In addition to stopping exposure to the toxic substance, healthcare providers may prescribe medicines and therapies to improve symptoms. These include:

  • Breathing exercises to improve technique
  • Drugs to suppress the immune system
  • Inhaled medications to open the airway
  • Oxygen to help with breathing

People who do not improve with these treatments may need a lung transplant.

What are the potential complications of bronchiolitis?

Bronchiolitis is generally manageable at home, but sometimes it can quickly worsen and lead to respiratory distress. This is a medical emergency. Take your child to the nearest emergency department or call 911. Hospital intensive care is necessary to stabilize breathing and respiration. Approximately 3% of children with bronchiolitis will require hospital care. People with bronchiolitis who are in respiratory distress may need to be intubated. A doctor will place a tube into their trachea (windpipe) until they are able to breathe on their own again.

Most children with bronchiolitis recover within a couple of weeks with no lasting effects. Possible complications, although rare, include:

  • Adverse reaction to medications
  • Infections acquired in hospital

Bronchiolitis obliterans

Adults with bronchiolitis obliterans could slow down the disease by getting an early diagnosis and following their treatment plan. Left untreated, the disease can be fatal.

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Medical Reviewer: William C. Lloyd III, MD, FACS
Last Review Date: 2021 Jun 27
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THIS TOOL DOES NOT PROVIDE MEDICAL ADVICE. It is intended for informational purposes only. It is not a substitute for professional medical advice, diagnosis or treatment. Never ignore professional medical advice in seeking treatment because of something you have read on the site. If you think you may have a medical emergency, immediately call your doctor or dial 911.
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