This product is used to control and prevent symptoms (wheezing and shortness of breath) caused by asthma or ongoing lung disease (chronic obstructive pulmonary disease-COPD, which includes chronic bronchitis and emphysema). It contains 2 medications: budesonide and formoterol. Budesonide belongs to a class of drugs known as corticosteroids. It works by reducing the irritation and swelling of the airways. Formoterol belongs to the class of drugs known as long-acting beta agonists. It works by relaxing the muscles around the airways so that they open up and you can breathe more easily. Controlling symptoms of breathing problems can decrease time lost from work or school. When used alone, long-acting beta agonists (such as formoterol) may rarely increase the risk of serious (sometimes fatal) asthma-related breathing problems. However, combination inhaled corticosteroid and long-acting beta agonists, such as this product, do not increase the risk of serious asthma-related breathing problems. Before using this medication, it is important to learn how to use it properly. If an asthma attack occurs, use your quick-relief inhaler (such as albuterol, also called salbutamol in some countries) as prescribed. See also How to Use section.