Theophylline is used to prevent and treat symptoms of asthma (a chronic inflammation of the airway tissues), bronchitis (an inflammation of the mucous membranes in the bronchial tubes, which connect the windpipe to the lungs), emphysema (a condition in which the air sacs in the lungs are damaged, interfering with the normal exchange of oxygen and carbon dioxide) and chronic obstructive pulmonary disease, or COPD (a chronic, progressive lung condition characterized by coughing, wheezing and shortness of breath). It relaxes and opens the air passages in the lungs, making it easier for a person to breathe.

Because of the dangers of toxicity associated with theophylline overdose, it no longer is the drug of first choice to treat these conditions. However, the drug may be combined with low-dose inhaled corticosteroids (medications that prevent the inflammation associated with asthma attacks) to increase the potency of asthma treatments. It also may be prescribed to treat COPD in situations where patients cannot breathe properly despite using both an inhaled beta2 agonist (medications that relax muscles in the air passageways to prevent narrowing and to open the airways) and an inhaled anticholinergic (medications that smooth muscle contractions and reduce excess mucus in the tubes that transport air to and from the lungs).