What is Bronchiolitis?

Bronchiolitis is a common lung infection in babies and young children, usually caused by respiratory syncytial virus (RSV). It causes inflammation and mucus build-up in the small airways of the lungs, leading to coughing, wheezing, and rapid or noisy breathing.

It's most common in babies under 1 year old and usually starts like a common cold before progressing over a few days. Most cases are mild and can be managed at home, but babies — especially those born prematurely or with other health conditions — can become seriously unwell and need hospital treatment.