What is bronchiolitis?

Bronchiolitis is common in babies and very small children up to 2 years old. It’s most common in babies between 3 and 6 months.

Premature babies and babies with existing heart or lung conditions are at greater risk of developing severe bronchiolitis.

Bronchiolitis makes your baby cough and become breathless. This makes it hard for them to breathe and feed.

It usually starts with a runny or blocked nose, and over 2-3 days the small airways in your baby's lungs get infected, inflamed and clogged up with mucus. 

In most cases their breathing and feeding will get better within 5 days. Their cough might take longer to go – usually by around 3 weeks.

Your baby is most likely to have it over the winter - between October and March.

You can find out more from More than a cold.

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Last medically reviewed: September 2016. Due for review: September 2019

This information uses the best available medical evidence and was produced with the support of people living with lung conditions. Find out how we produce our information. If you’d like to see our references get in touch.