Inhaled corticosteroids are medications used to treat asthma. They are taken by using an inhaler. This medication should be taken consistently so that it decreases inflammation in the airways of your lungs and prevents asthma flare-ups. Inhaled corticosteroids are considered the most effective long term usage medication for control and management of asthma. Depending upon the severity of your asthma, your physician may combine an inhaled corticosteroid with a long-acting beta-2 agonist to treat your condition. Oral and intravenous corticosteroids may be required for acute asthma flare-ups or for severe symptoms.