This guideline covers diagnosing and managing bronchiolitis in babies and children. It aims to help healthcare professionals diagnose bronchiolitis and identify if babies and children should be cared for at home or in hospital. It describes treatments and interventions that can be used to help with the symptoms of bronchiolitis. In August 2021, we reviewed the evidence and updated the recommendations on oxygen saturation thresholds for referral to hospital, admission, management and timing of discharge.