Glucocorticoid steroids such as cortisol or budesonide have potent anti-inflammatory actions that reduces inflammation and hyper-reactivity (spasm) of the airways caused by asthma. When used as an inhaler, the budesonide goes directly to the inner lining of the inflamed airways to exert its effects. Only 39% of an inhaled dose of budesonide is absorbed into the body, and the absorbed budesonide contributes little to the effects on the airways.