During a prospective 10-week assessment period, 3238 children aged 1-16 years presented with acute wheeze to Paediatric Emergency Research in the UK and Ireland centres. 110 (3.3%) received intravenous bronchodilators. Intravenous magnesium sulfate (MgSO4) was used in 67 (60.9%), salbutamol in 61 (55.5%) and aminophylline in 52 (47.3%) of cases. In 35 cases (31.8%), two drugs were used together, and in 18 cases (16.4%), all three drugs were administered. When used sequentially the most common order was salbutamol, then MgSO4, then aminophylline. Overall, 30 different intravenous treatment regimens were used varying in drugs, dose, rate and duration.