Stating the obvious: intravenous magnesium sulphate should be the first parenteral bronchodilator in paediatric asthma exacerbations unresponsive to first-line therapy.

What is the most appropriate second-line intravenous bronchodilator treatment when a child with a severe asthma attack is not responsive to initial inhaled therapy? The second-line treatment options for acute asthma include parenteral β2-agonists, methylxanthine and magnesium sulphate (MgSO4). There is a poor evidence-base to inform this decision. This review argues that intravenous MgSO4 is the obvious treatment of choice for this situation as the initial treatment based on current knowledge.  We describe the mode of action, scope and limitations of MgSO4, safety profile, economic impact, comparisons of the alternatives, and finally, what the guidelines say.  This review explores the suitability of intravenous MgSO4 as a pragmatic and safe initial second-line therapy for children unresponsive to initial asthma management.