A two-year-old was diagnosed with croup — a viral infection of the upper airway — after his family noticed that his voice had turned hoarse and he had a barking cough, which his doctor said are characteristic symptoms of the infection.

The symptoms and other signs of croup are the results of swelling around the larynx and trachea, Taipei Shu-tien Clinic pediatrician Tai Chi-shan (戴季珊) said.

When air travels through the narrowed airway, it produces a loud and hoarse sound as the person inhales or exhales, Tai said.

Croup often worsens or develops at night and could even be fatal if the symptoms are severe, she said.

It is a common disease among children aged six months to three years old, especially during seasonal changes.

The infection is less common among older children, she said, adding that boys are slightly more susceptible to it than girls.

Many parents mistake croup for asthma, but they are completely different. Croup features a characteristic barking cough due to an infected upper airway, where a swollen throat and tissues make inhaling more difficult than exhaling, Tai said.

Asthma is characterized by a whistling breathing sound due to lower airway obstruction, where contraction of the inflamed bronchial muscle makes exhaling more difficult than inhaling, she added.

Croup is usually not serious and can be treated at home, but children who have croup and breathe with a wheezing sound even when not crying or agitated, or develop breathlessness, should seek a pediatrician’s advice on whether an adrenaline spray and long-lasting steroids are needed to reduce airway swelling, Tai said.

Noting that croup — which resembles a typical cold at the early stage — is also contagious, Tai said that enhanced household hygiene measures should be implemented if any family member has the infection.

People with croup should seek medical assistance immediately if they find themselves having a difficult time breathing and swallowing, becoming weak and pale, or if their symptoms last beyond seven days, she added.