A previously well, 18 month old, 10.5 kg boy presented with a four week history of intermittent cough and wheeze. In the week prior to admission he developed a fever, increasing lethargy, anorexia, and refusing to drink adequately. His fever was initially treated with paracetamol (5 ml (120 mg) up to four times a day), but with a persisting fever ibuprofen was then given in addition over the subsequent week at the correct dose (2.5 ml (50 mg), maximum six doses), until three days prior to admission, during which time he was noted to have increasingly dry nappies. On examination he was afebrile, sleepy but rousable, mildly dehydrated, with normal capillary refill and normal blood pressure (90 mm Hg systolic). He was mildly tachypnoeic (38 breaths/min) with scattered expiratory wheeze. Urinalysis showed 2+ protein, 1+ glucose, and no blood. Phase contrast microscopy revealed one mixed cellular cast but no cells or organisms. He was profoundly hyperkalaemic (potassium 8.7 mmol/l), acidotic (bicarbonate 12 mmol/l), and uraemic (urea 69.6 mmol/l, creatinine 523 μmol/l). Blood glucose was 9.2 mmol/l with subsequent normal values. A full blood count and film was normal except for a raised white cell count (21.6×109/l) with a predominant neutrophilia. C3 and C4 complement levels and an autoantibody profile were normal. A nasopharyngeal aspirate ultimately confirmed a respiratory syncytial virus infection to account for his cough and wheeze.