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Overview

What Is Bronchiolitis?

Bronchiolitis is inflammation and swelling of the small airways in the lungs, usually caused by a virus. It most commonly affects infants and children younger than 2 years. Symptoms often include congestion, cough, wheezing, and trouble breathing. Bronchiolitis is different from bronchitis: bronchitis affects the larger airways, while bronchiolitis affects the smallest airways.

Symptoms

Bronchiolitis Symptoms

Bronchiolitis symptoms often begin like a common cold and may worsen over several days as the small airways become inflamed. Knowing the typical bronchiolitis symptoms can help families notice breathing or hydration problems early.

  • A runny nose is often one of the first symptoms.
  • A cough may develop or become more frequent.
  • Wheezing can cause a high-pitched or whistling breathing sound.
  • Fast breathing (tachypnea) may occur as the child works harder to breathe.
  • The skin may pull in between or under the ribs during breathing (retractions).
  • Difficulty feeding may occur because breathing and sucking are hard to coordinate.
  • Fewer wet diapers can be a sign of reduced fluid intake or dehydration.
  • Fever may occur, although it is not present in every child.
  • Unusual tiredness or reduced alertness can occur with more significant illness.
  • Pauses in breathing (apnea) require urgent medical attention, especially in young infants.

How It Spreads

How Bronchiolitis Spreads

Bronchiolitis itself is the inflammation of the small airways, while a virus causes the infection behind it. Respiratory viruses such as respiratory syncytial virus (RSV) can spread through coughs and sneezes, close contact, hands, and contaminated surfaces. A person can pass on the virus before or while symptoms are present.

How Long Is Bronchiolitis Contagious?

How long bronchiolitis is contagious depends on the virus causing the illness. Many respiratory viruses spread for several days, but infants and people with weakened immune systems may spread some viruses for longer. Because the timing varies, continue precautions while symptoms are active and follow advice from a healthcare professional.

  • Wash hands with soap and water or use alcohol-based hand sanitizer.
  • Cover coughs and sneezes and dispose of tissues promptly.
  • Clean frequently touched surfaces and shared objects.
  • Avoid close contact between sick people and infants or other high-risk individuals.
  • Do not share cups, utensils, towels, or pacifiers.

Risk Factors

Bronchiolitis Risk Factors

Many infants develop mild illness, but younger age and certain health or environmental factors increase the risk of severe bronchiolitis or hospitalization. Some factors cannot be changed, while families can reduce others, such as tobacco smoke exposure and avoidable contact with respiratory viruses.

  • Being younger than 3 months increases the risk of severe illness and is not a changeable factor.
  • Premature birth can increase the risk of breathing complications and cannot be changed after birth.
  • Chronic lung disease can make respiratory infections harder to tolerate.
  • Congenital heart disease can increase the risk of severe bronchiolitis.
  • Neuromuscular conditions can make it harder to clear airway secretions.
  • A weakened immune system can increase the risk of serious infection.
  • Exposure to tobacco smoke can worsen respiratory illness risk and should be avoided.
  • Crowded childcare or household settings can increase exposure to respiratory viruses.

Complications

Bronchiolitis Complications

  • Dehydration can occur when congestion and fast breathing make feeding difficult.
  • Low blood oxygen can occur when inflamed small airways limit airflow.
  • Apnea is a pause in breathing that is more concerning in very young or premature infants.
  • Respiratory failure is uncommon but may require hospital-based breathing support.
  • A secondary bacterial infection can occasionally develop after the viral illness.

Diagnosis

How Bronchiolitis Is Diagnosed

A clinician typically diagnoses bronchiolitis from the child’s age, symptom pattern, breathing rate, work of breathing, hydration, and lung examination. The diagnosis is usually clinical, meaning routine extensive testing is not needed in uncomplicated cases.

  • A pulse oximeter may measure the oxygen level in the blood.
  • The clinician may assess feeding, wet diapers, and other signs of hydration.
  • Viral testing may be used when the result will affect treatment or infection-control decisions.
  • Chest imaging or blood tests are usually reserved for suspected complications or an alternative diagnosis.

IMPORTANT

Other conditions can look similar

Wheezing, cough, and breathing difficulty can also occur with asthma, pneumonia, croup, or a swallowed object. Evaluation is important when symptoms are severe, atypical, or prolonged.

Treatment & Management

Bronchiolitis Treatment and Management

Most cases improve with supportive care rather than a specific antiviral medicine. A clinician should guide care for young infants and children with underlying conditions because they may become dehydrated or have more serious breathing problems.

  • Use saline nose drops and gentle nasal suction before feeds or sleep when congestion interferes with breathing.
  • Offer smaller, more frequent feeds to help maintain hydration.
  • Keep the child away from tobacco smoke and other airway irritants.
  • A cool-mist humidifier may ease dry air but must be cleaned and placed safely out of reach.
  • Use fever medicine only as directed by a healthcare professional for the child’s age and weight.

Prevention

Can Bronchiolitis Be Prevented?

  • Wash hands before touching an infant and after contact with someone who is sick.
  • Keep infants away from people with cold symptoms whenever possible.
  • Clean toys, pacifiers, and frequently touched household surfaces regularly.
  • Breastfeeding may provide some protection against respiratory infections when it is possible for the family.
  • Keep the home and car smoke-free.
  • Ask a healthcare professional whether the infant qualifies for an available RSV preventive antibody or maternal RSV vaccination strategy.

Outlook and Prognosis

Bronchiolitis Outlook and Prognosis

Most children recover fully from bronchiolitis. Symptoms often worsen before improving, and cough or noisy breathing may linger for several weeks without necessarily meaning the infection is still getting worse. Children with severe symptoms or underlying health conditions may need closer follow-up.

  • Cold-like symptoms commonly appear first.
  • Cough, wheezing, and breathing effort may peak over the next few days.
  • Breathing and feeding usually improve gradually with supportive care.
  • A lingering cough can last longer than the fever or congestion.
  • Persistent, recurrent, or worsening symptoms should be reassessed for another condition or complication.

When Should You See a Doctor

When Should You See a Doctor for Bronchiolitis?

SEEK EMERGENCY CARE

Get immediate medical help

Seek emergency care for severe difficulty breathing, pauses in breathing, blue or gray lips or skin, marked limpness or inability to wake, or signs of severe dehydration.

  • Contact a clinician promptly if a baby younger than 3 months has a fever or breathing symptoms.
  • Seek medical advice if breathing becomes faster, noisier, or more effortful.
  • Call if the child cannot feed normally or has noticeably fewer wet diapers.
  • Arrange assessment if fever persists, returns, or is accompanied by worsening symptoms.
  • Ask for reassessment if symptoms are prolonged, recurrent, or not gradually improving.

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