Viral causes of bronchiolitis

A respiratory virus can begin with a blocked or runny nose, then move into the smaller airways. Swelling and mucus narrow these tubes, making each breath noisier and increasing the effort needed to breathe. Babies may tire during feeds because sucking, swallowing, and breathing become harder together.

The illness may occur with or without [Fever](/symptoms/fever/). A cough and [Wheezing](/symptoms/wheezing/) can continue while the airways recover; the presence of one symptom does not identify the virus by itself.

Keep the child away from smoke and sick contacts where practical. Offer smaller feeds more often, allow rest, and gently clear nasal secretions before feeding. Watch breathing rather than relying only on temperature. Antibiotics do not treat viruses, and cough or cold medicines should not be given to a young child unless a clinician recommends them. A clinician can explain whether supportive care or [Nebuliser Treatment](/treatments/acute-and-urgent-care/nebuliser-treatment/) has a role.

Seek urgent care for pauses in breathing, marked chest pulling, blue or grey lips, severe tiredness, or inability to drink. Contact a clinician promptly if feeds are repeatedly interrupted, wet nappies become less frequent, or breathing is getting faster or harder. A [Child Health Consultation](/treatments/consultations-and-assessment/child-health-consultation/) provides a focused assessment.

Ask what signs show that breathing is improving, how much fluid the child should manage, whether testing is needed, and when to return for review. Tell the clinician when symptoms started and how feeding has changed.