What causes bronchiolitis?

The virus spreads through coughs, sneezes, close contact, and contaminated hands or surfaces. Swelling and mucus narrow the small air passages in a baby's or young child's lungs. This can begin like a cold, with a runny nose, cough, and fever, then progress to faster or noisier breathing, wheezing, and difficulty feeding.

The illness is commonly seen in infants because their airways are narrow. Premature babies and children with heart, lung, or immune problems may become more unwell, so their usual breathing and feeding deserve close attention. Read more about [Bronchiolitis](/conditions/bronchiolitis/).

Keep the child upright while awake, offer smaller feeds more often, and clear the nose gently if congestion makes feeding difficult. Check breathing and wet nappies regularly. Keep smoke and strong fragrances away from the child, and wash hands before care. Do not give cough medicines or antibiotics unless a clinician specifically recommends them; antibiotics do not treat a viral cause.

Get urgent medical help if the child is struggling to breathe, the skin between or below the ribs pulls in, breathing pauses, lips look blue or grey, the child is unusually floppy, or they cannot take feeds. Seek prompt advice if wet nappies become much less frequent, fever concerns you, or breathing is steadily worsening. A baby who seems exhausted during feeds needs assessment rather than observation alone.

Ask: How severe is the breathing difficulty? Is feeding and hydration adequate? What signs should I check overnight, and where should I go if breathing worsens? Does this child have a reason to need closer monitoring?