Magnesium sulfate may be administered via intravenous infusion for the treatment of acute asthma exacerbations. It has a direct relaxing effect on bronchial smooth muscle. The mechanisms of action include inhibition of cholinergic neuromuscular transmission, calcium channel blockade, mast cell and T-lymphocyte stabilization, and stimulation of nitric oxide and prostacyclin. Clinical trials have demonstrated improved airflow and decreased hospitalization when magnesium is used as an adjunct for the treatment of severe asthma attacks. The side effects include warmth, flushing, sweating, nausea and vomiting, muscle weakness and loss of deep tendon reflexes, hypotension, and respiratory depression. These side effects are typically dose-related and managed by slowing or stopping the infusion.