What should you know about the virus that causes bronchiolitis?

Respiratory syncytial virus is a common cause, although other cold viruses can produce the same illness. Bronchiolitis affects the smallest breathing tubes, so a baby may feed slowly, tire during feeds or use extra muscles around the ribs to breathe. Symptoms often begin like a cold and then become more noticeable over the following days. A cough, fever or [Wheezing](/symptoms/wheezing/) may occur; the presence of one symptom does not identify the virus by itself.

Offer frequent breastfeeds or small amounts of the usual fluid, keep the child upright while awake, and clear visible mucus gently before feeds. Avoid tobacco smoke and do not give cough medicines unless a clinician specifically recommends them. A clinician may assess breathing, hydration and oxygen levels; selected children may need a [Child Health Consultation](/treatments/consultations-and-assessment/child-health-consultation/) or supportive treatment such as [Nebuliser Treatment](/treatments/acute-and-urgent-care/nebuliser-treatment/). Antibiotics do not treat viruses.

Seek urgent medical help if the child is struggling to breathe, has pauses in breathing, turns blue or grey around the lips, is unusually difficult to wake, or is taking very little fluid. Arrange prompt assessment if wet nappies become less frequent, breathing is getting faster, or the child is worsening after seeming stable. Babies who were born prematurely or have heart, lung or immune problems may need earlier advice.

Ask whether the breathing effort and hydration are reassuring, how to count breaths at home, and which changes should trigger urgent review. You can also ask whether a [Cough](/symptoms/cough/) or [Fever](/symptoms/fever/) needs separate treatment.