By Philip R. Fischer, MD, DTM&H

Dr. Fischer is Professor of Pediatrics, Department of Pediatric and Adolescent Medicine, Mayo Clinic, Rochester, MN.

Dr. Fischer reports no financial relationships relevant to this field of study.

SYNOPSIS: Bronchiolitis is a common infection caused by several different viruses; 20% of children in the United States seek medical care for respiratory syncytial virus (RSV), a common cause of bronchiolitis, during the first year of life. Supportive care is effective, but many children still receive pharmacologic treatments that have been proven to be ineffective.

SOURCE: Meissner HC. Viral bronchiolitis in children. N Engl J Med 2016;374:62-72.

Bronchiolitis is a common problem caused by respiratory syncytial virus (RSV) and other viruses. Each year in the United States, approximately 20% of children younger than a year of age require medical care for RSV infection, and 2-3% (about 100,000) of children are hospitalized with bronchiolitis. Globally, bronchiolitis accounts for up to 200,000 pre-school-aged deaths each year.

While clinical presentations of bronchiolitis vary, there are usually a few days of nasal congestion, runny nose, and low-grade fever, followed by worsening cough. Respiratory distress can manifest as tachypnea and retractions. Wheezing is often heard on auscultation. Apnea can be seen early in the course of the illness, especially in prematurely born children. Severe bronchiolitis requiring hospitalization is most common at 1 to 3 months of age, likely related to declining levels of protective antibodies that had been acquired trans-placentally. Prematurely born babies and infants with congenital heart disease are at increased risk of severe bronchiolitis.

Severe bronchiolitis is associated with a subsequent risk of developing asthma. It is not known, however, whether the infection prompts the development of asthma or whether lungs destined to get asthma are already altered in ways that make them more likely to develop severe bronchiolitis.

RSV is the most common viral cause of bronchiolitis and accounts for more than half of cases; it is most common in November through April in North America. Especially in autumn and spring, rhinovirus and parainfluenza virus cause bronchiolitis. The peak incidence of human metapneumovirus-related bronchiolitis is usually a month or two after the peak of RSV bronchiolitis. Coronavirus, adenovirus, influenza, and enterovirus can also cause bronchiolitis.

The treatment of bronchiolitis is largely supportive in nature. Good studies have demonstrated the inefficacy of several interventions, including diagnostic radiographs, viral testing, bronchodilators such as albuterol, glucocorticoids, antimicrobial agents, chest physiotherapy, and supplemental oxygen when the oxygen saturation is still at or above 90%.


Bronchiolitis is a global problem. In eastern Kenya, RSV accounts for 20% of hospitalizations for severe respiratory infection during the first six months of life.1 In Thailand, RSV accounts for 29% of lower respiratory tract infections during the first year of life, but the season is usually from July to October.2

Most of us reading this article at the time of its publication are working in North American settings where many children are being treated for bronchiolitis. As noted by Dr. Meissner in this new review article and as detailed in late 2014 by the American Academy of Pediatrics,3 aggressive interventions do not usually help children with bronchiolitis recover any better than does supportive care. For instance, strong scientific evidence suggests that several common measures should not be routine in the care of children with bronchiolitis. Chest X-rays are associated with overtreatment with antibiotics, since atelectasis seen with viral infections masquerades as focal infiltrates. Viral testing is costly without altering isolation measures, treatment, or outcome. Bronchodilators and steroids are ineffective. Antimicrobial agents do not help. Oxygen does not improve outcomes in children with at least 90% saturation on room air. Even continuous testing of pulse oximetry delays hospital dismissals without reducing complications in patients.

Nine years ago, a commentary in the New England Journal of Medicine pointed out that more than half of patients with bronchiolitis were treated with interventions known not to be effective. Clearly, we still find that withholding therapy is much more difficult than giving it; we tend to want to “do something” rather than “just” provide supportive care. Evidence should guide our decisions to use and not to use specific interventions.

Now, it is time to manage bronchiolitis based on scientific evidence. Doing so, “less is more” in that provision of less intervention will actually best help most young children with bronchiolitis.


  1. Nokes DJ, Ngama M, Bett A, et al. Incidence and severity of respiratory syncytial virus pneumonia in rural Kenyan children identified through hospital surveillance. Clin Infect Dis 2009;49:1341-1349.
  2. Suntarattiwong P, Sojisirikul K, Sitaposa P, et al. Clinical and epidemiological characteristics of respiratory syncytial virus and influenza virus associated hospitalization in urban Thai infants. J Med Assoc Thai 2011;94:S164-S171.
  3. Ralston SL, Lieberthal AS, Meissner HC, et al. Clinical practice guideline: The diagnosis, management, and prevention of bronchiolitis. Pediatrics 2014;134:e1474-e1502.
  4. Hall CB. Therapy for bronchiolitis: When some became none. N Engl J Med 2007;357:402-404.