Formoterol is a long-acting bronchodilator used as a long-term (maintenance) treatment to prevent or decrease wheezing and trouble breathing caused by asthma or ongoing lung disease (chronic obstructive pulmonary disease-COPD, which includes chronic bronchitis and emphysema). It should only be used long-term if your asthma symptoms are not controlled by your other asthma medications (such as inhaled corticosteroids). Formoterol must not be used alone to treat asthma. (See also Warning section.) 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.This drug is also used to prevent breathing difficulties brought on by exercise (exercise-induced bronchospasm-EIB).This medication should not be used for a severe/sudden asthma attack. For sudden attacks of asthma, use your quick-relief inhaler as prescribed. This medication is not a substitute for inhaled or oral corticosteroids (such as beclomethasone, fluticasone, prednisone). This medication should be used along with another controller-type asthma medication (such as inhaled corticosteroids). However, it should not be used with other long-acting beta-agonist inhalers (such as arformoterol, salmeterol) because doing so may increase your risk for side effects.It is recommended that children and teenagers, who need to use formoterol to treat their asthma, should use a combination formoterol/budesonide product. Check with your child's doctor to see if this product is the right product for your child.