Wheezing is a high-pitched, musical, or whistling noise produced as air is forced through narrowed lower airways, specifically the small tubes in the lungs called bronchioles. This sound is a sign of obstruction and commonly occurs during exhalation, reflecting a struggle to push air out past the constriction.
Differentiating Wheezing from Other Noises
The first step is correctly identifying the sound, as not all noisy breathing is true wheezing. True wheezing is a high-pitched whistle that originates in the chest and is most prominent when your baby breathes out, signaling a problem in the lower respiratory tract. This is a sound created by the turbulent flow of air through the constricted lower airways.
A different sound, called stridor, is a harsh, high-pitched noise typically heard on inhalation, indicating an obstruction in the upper airway, such as the voice box or windpipe. Another common infant noise is stertor, a low-pitched snorting or rattling sound originating from mucus in the nose or back of the throat. Stertor is often mistaken for wheezing but is simply the sound of upper airway congestion.
Common Underlying Causes
The primary reason infants wheeze is the small size of their airways, making them highly susceptible to narrowing from inflammation. Approximately 25 to 30 percent of infants will experience at least one episode of wheezing, often linked to viral respiratory infections. These infections cause the lining of the bronchioles to swell and produce mucus, reducing the space for air to pass.
The most frequent cause of wheezing is bronchiolitis, a lower respiratory tract infection often caused by Respiratory Syncytial Virus (RSV). RSV infection leads to significant inflammation and mucus buildup in the tiny bronchioles, which can be life-threatening in very young babies. Other common viruses, including those that cause the common cold, can also trigger wheezing.
Some infants experience transient infant wheezing, a benign pattern that usually resolves by age three and may not be linked to later asthma. Wheezing may also be caused by exposure to environmental irritants, such as secondhand tobacco smoke or air pollutants, which irritate the airway lining. Less commonly, conditions like gastroesophageal reflux disease (GERD) or mild allergic reactions can contribute to airway inflammation.
Signs Requiring Immediate Medical Attention
Wheezing accompanied by signs of respiratory distress requires immediate evaluation by a medical professional or a trip to the emergency room. One concerning sign is retractions, where the skin visibly pulls inward between the ribs, above the collarbone, or beneath the breastbone with each breath. This means the baby is using accessory muscles and working hard to move air into their lungs.
Changes in skin color are a grave sign, specifically a bluish tint around the lips, mouth, or on the fingernails, known as cyanosis. This indicates a dangerously low level of oxygen in the blood. An increased rate of breathing or the appearance of nasal flaring, where the nostrils widen with each breath, also signals a serious struggle for air.
Grunting sounds on exhalation are another red flag, as the baby is trying to keep air sacs open by breathing out against a partially closed throat. If your baby is unusually lethargic, irritable, or refuses to feed or drink, these behavioral changes signal a worsening respiratory status. Any wheezing that is sudden, loud, and unresponsive to home care warrants immediate medical attention.
Diagnosis and Treatment Options
When a parent seeks medical help, the initial assessment involves a physical examination and listening to the baby’s chest with a stethoscope to confirm the wheeze’s presence and location. A non-invasive test called pulse oximetry is routinely performed, using a sensor placed on a finger or toe to measure the oxygen saturation level in the blood.
To determine the underlying cause, the doctor may order a chest X-ray to look for signs of pneumonia, a foreign object in the airway, or structural anomalies. Viral swabs are often collected to identify specific pathogens, such as RSV, which informs the expected course of the illness. For mild cases, treatment starts with supportive home care, including using a cool-mist humidifier and gently suctioning mucus from the nose to clear the upper airway.
Medical interventions can include bronchodilator medications, such as albuterol, delivered via a nebulizer or a metered-dose inhaler with a spacer, to relax and open the constricted airways. In situations with severe inflammation, a short course of oral or inhaled corticosteroids may be prescribed to reduce swelling in the bronchioles. Infants showing signs of significant respiratory distress or low oxygen levels may require hospitalization for closer monitoring and supplementary oxygen therapy.