Prevent Wheeze Trial

This trial investigates whether a single dose of dexamethasone will prevent recurrent wheezing in children at high-risk for asthma admitted to hospital with a lower respiratory tract infection (LRTI). Eligible children will be identified and enrolled upon hospital admission or during hospitalisation and allocated to receive either dexamethasone 0.6 mg/kilogram body weight or the similar number of placebo tablets (allocation ratio 1:1). The follow-up is 12 months and comprises scheduled on-site examinations by physician and study nurse, scheduled phone contacts, and registrations of new LRTI-episodes (if any). Nasopharyngeal swabs and blood will be collected at specified visits. The children will be invited to a follow-up study at school age for lung function assessments.

Inclusion criteria: 1. Age 3-24 months 2. LRTI (WHO definition LRTI: Cough or difficulties breathing \+ plus either fast breathing ( 2-12 months: \> 50 breaths/minute 13-24 months: \>40/minute) or: lower chest wall indrawing (retractions/nasal flare/difficulties breathing/wheeze) Acute:\=1 for wheeze item). The scoring matrix is here and in the annex. * Indoor pollution exposure: Tobacco smoke exposure a) during pregnancy or b) in house where child lives (regular \>= 2week) or polluting cooking facility * Atopic/allergic disease in child * Atopic/allergic/asthma in sibling, mother or father * PT week 34-36 or BW 2000-2500g * Eosinophil count \>0.30 Informed consent Exclusion criteria: * Chronic illness other than atopy (eczema, food allergy), * Systemic corticosteroid treatment the previous 6 months * Inhaled corticosteroid treatment, at any time, for \>2 weeks * Clinical suspicion of bacterial pneumonia based upon a temperature ≥39.0°C and at least one of the following: 1. Unilaterally decreased breath sounds or unilateral percussion dullness 2. Pulmonary lobar consolidation and/or radiological high suspicion of empyema on chest x-ray if this is obtained prior to inclusion in the trial. Fills other criteria for high likelihood of bacterial pneumonia (on clinicians' evaluation or CRP\>40) * Evidence of any bacterial infection other than bacterial LRTI, including, but not exclusively: 1. Clinical septicemia 2. Urinary tract infection 3. Meningitis * participation in another trial * varicella infection or contact during the last 2-3 weeks * Fulfill criteria for ICS at time of inclusion, at treating physicians discretion, guided by annex on criteria for unblinding due to medical condition needing open CS treatment (criteria for unbinding Criteria for unblinding.docx) * Severe wheeze defined by TAL score\* \>=11 or need for intensive care unit treatment with invasive ventilation at screening. * Previous admission for a LRTI or physician verified LRTI