The airway may be narrowed because of swelling, secretions or a foreign object. Narrowing of the airway obstructs air coming in and going out. Infections or allergies can cause increased swelling and secretions. In some conditions, children make a noise or wheeze only as they take a breath. This sound is called stridor and is a feature of croup.
Frequent cough can indicate sinusitis, bronchiolitis, or pneumonia.
A frequent dry cough may be an indication of asthma with bronchial spasms. Look at the rib cage to see if the spaces between the ribs are sucked in when taking a breath. The space above the breastbone is often sucked in, indicating the use of accessory muscles. The abdominal muscles are also used to help in breathing. In a child you may observe the abdomen going up and down in an exaggerated manner.