The most common medication used is a beta agonist taken about 20 minutes before exercise.[16] Some physicians prescribe inhaled anti-inflammatory mists such as corticosteroids or leukotriene antagonists, and mast cell stabilizers have also proven effective.[16] A randomized crossover study compared oral montelukast with inhaled salmeterol, both given two hours before exercise. Both drugs had similar benefit but montelukast lasted 24 hours.[17]