Introduction Despite the evidence supporting the use of intravenous Magnesium Sulfate (MS) in acute asthma; this drug continues being considered as the second line in pediatric acute asthma exacerbations. This study aimed to evaluate the cost-effectiveness of the MS in acute asthma. Methods A decision tree model was used to estimate the Cost-utility study that compared MS versus standard treatment (control group) in an infant with acute asthma in the emergency setting. Cost data were obtained from a retrospective study on asthma from tertiary centers in Rionegro, Colombia, while utilities were collected from the literature. The analysis was carried out from a societal perspective. Results The model showed that MS for treating pediatric patient with acute asthma, was associated with lower total cost than standard therapy (US $1149 vs US $1598 average cost per patient), and higher QALYs ( 0.60 vs 0.52 average per patient); showing dominance. the probabilty that MS provides a more cost-effective use of resources compared with standard therapy exceeds 99% for all willingness to pay thresholds Conclusion MS in emergency settings was cost-effective for the hospital treatment of an infant with asthma moderate or severe. Our study provides evidence that should be used by decision-makers to improve clinical practice guidelines and should be replicated to validate their results in other middle-income countries.