The addition of a long acting beta agonist (LABA) to inhaled corticosteroid (ICS) therapy can improve asthma symptoms and reduce exacerbations. The addition of LABA may also have an ICS-sparing effect and permit a reduction in ICS maintenance dose.
Gibson, P. G., Powell, H., & Ducharme, F. M. (2005). Long-acting beta2-agonists as an inhaled corticosteroid-sparing agent for chronic asthma in adults and children. Cochrane Database of Systematic Reviews. https://doi.org/10.1002/14651858.cd005076.pub2