Nasal flaring is the enlargement of the opening of the nostrils during breathing. It is often a sign that increased effort is needed to breathe.

Nasal flaring is seen mostly in infants and younger children.

Any condition that causes the infant to work harder to breathe can cause nasal flaring. While many causes of nasal flaring are not serious, some can be life threatening.

In young infants, nasal flaring can be a very important symptom of respiratory distress.

• Asthma (acute)
• Airway obstruction (any cause)
• Bronchiolitis
• Croup
• Epiglottitis (acute)
• Pneumonia
• Transient tachypnea of the newborn

Seek immediate emergency help if you or your child has signs of a breathing difficulty.

Call your health care provider if:

• There is any persistent, unexplained nasal flaring, especially in a young child.
• Bluish color develops in the lips, nail beds, or skin. This is a sign that breathing difficulty is severe and may mean that an emergency condition is developing.
• You thing that your child is having trouble breathing.

The health care provider will perform a physical exam to determine if the flaring is due to upper or lower respiratory problems. The exam will include careful listening to the breath sounds. This is calledauscultation.

Medical history questions may include:

• When did it start?
• Is the person getting better or worse?
• Does the person look blue?
• Is the breathing noisy or are there wheezing sounds?
• Are there grunting noises with the breathing?
• Does the person look like they are working hard to breathe?
• Are they getting tired or sweaty?
• Do the muscles of the stomach, shoulders, or rib cage need to be used when the person is breathing? (See: intercostal retractions)
• What other symptoms does the person have?

The following tests may be performed:

• Arterial blood gas analysis
• Complete blood count (CBC)
• ECG
• Pulse oximetry to measure blood oxygen level
• X-rays of the chest

The patient may be given oxygen.

Wiebe RA. General Approach to the Pediatric Patient. Marx J. Rosen’s Emergency Medicine: Concepts and Clinical Practice. 6th ed. St. Louis, Mo: Mosby; 2006: Chap. 164.