Don't use IV magnesium for bronchiolitis. It doesn't work, and it may cause harm.
Why does this matter?
Not much works for bronchiolitis including steroids, hypertonic saline, albuterol, and now we add to that list, IV magnesium. Bronchiolitis is not the same as bronchospasm or asthma. So it doesn't respond to the same treatments, such as bronchodilators. Suction, support, O2, and observation are key.
No mag for you
This was a RCT of IV magnesium sulfate 100mg/kg vs placebo in children with bronchiolitis, about 80 per group, with the primary outcome of time to discharge. Magnesium had no effect. More children in the Mg group were readmitted within 2 weeks. It didn't cause adverse cardiac or respiratory effects, such as hypopnea or hypotension.
IV Magnesium Sulfate for Bronchiolitis: A Randomized Trial. Chest. 2017 Jul;152(1):113-119. doi: 10.1016/j.chest.2017.03.002. Epub 2017 Mar 9.
Peer reviewed by Thomas Davis, MD.