Theophylline, another long-term asthma control medication, is available as a tablet, capsule, or syrup. Theophylline relaxes the smooth muscles around the airways. A theophylline blood level between 5-15 mcg/ml usually gives relief of symptoms while avoiding side effects. Theophylline is not one of the first medications used for long-term control of asthma or other chronic lung diseases. There are safer and more effective medicines available, such as inhaled steroids and leukotriene modifiers.
The side effects of theophylline may include stomach upset, headache and although rare, seizures and heart arrythmias. In addition, blood levels need to be monitored and certain medicines can cause theophylline levels to increase.