Theo-Dur, Generic Theo-Dur, Theophylline is a bronchodilator.

Theophylline works in several ways: it relaxes muscles in the lungs and chest to allow more air in, it decreases the sensitivity of the lungs to allergens and other substances that cause inflammation, and it increases contractions of the diaphragm to draw more air into the lungs.

Theophylline is used to treat the symptoms of asthma, bronchitis and emphysema.