What is bronchiolitis?

Written by Yuppo Lab Experts.

Updated 27 October 2026

Bronchiolitis is a common viral infection of the small airways in the lungs that mostly affects babies under 1 and children under 2. It is most often caused by RSV and usually starts like a cold before a cough and faster breathing develop.

Key takeaways

  • Most babies get better at home within 2 to 3 weeks.
  • Symptoms are often worst around days 3 to 5.
  • Antibiotics do not help, because it is caused by a virus.

What you can do

  • Offer smaller, more frequent feeds.
  • Keep your baby upright when awake to ease breathing, but always put them on their back to sleep.
  • Keep your home smoke-free.

When to talk to your doctor

Call your local emergency number if your baby is struggling to breathe (the skin pulls in under the ribs), has pauses in breathing, or has blue or grey lips or tongue. See a doctor urgently if they are feeding less than half their usual amount, have far fewer wet nappies, or have a high temperature.

Frequently asked questions

Handwashing helps, and in many countries there are RSV immunisations for babies or vaccines in pregnancy; ask your doctor.

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