Theo-24 (generic: theophylline) is a prescription medication used to treat chronic (ongoing) lung diseases such as asthma, emphysema, and chronic bronchitis. This medication belongs to a group of drugs called methylxanthines. It works by relaxing the muscles of the airways, which opens airway passages and allows more air to get into the lungs. This action relieves wheezing, shortness of breath, and chest tightness.

Theo-24 comes in a sustained-release tablet. It is usually taken once or twice daily. Take this medication on an empty stomach, unless your doctor tells you otherwise. Swallow tablets whole. Do not crush or chew Theo-24 sustained-release tablets.

Common side effects include nausea, headache, and insomnia.