Bronchodilators are sometimes called either “rescue” or “control” medications. Rescue medications are usually short-acting and are used for quick relief from symptoms. They work by relaxing the bands of muscle surrounding the airways.Control medications are long-acting medications taken daily to prevent breathing difficulties from occurring and to prevent long-term damage to the airways. Patients continue to take these medications even when symptoms do not occur.ral forms of bronchodilators tend to have more side effects because they are delivered in higher doses and absorbed into the bloodstream. Inhaled bronchodilators are directly deposited in the lungs and tend to cause fewer side effects.