Theophylline: Long-Term Control Medications Make an Appointment Ask a Question Search Conditions 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. Side Effects 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. Get answers to frequently asked questions about theophylline. Common Theophyllines Medicine Name How the Medicine Works How the Medicine is Used Uniphyl® Theo-24 and others (theophylline) Relaxes the smooth muscles around the airways Needs to be taken on a regular schedule to maintain a blood level Theophylline blood level between 5-15 mcg/ml usually gives relief of symptoms while avoiding side effects. There are safer and more effective medicines available, such as inhaled steroids and leukotriene modifiers. Available as pills, syrups Prescribed to take 1-2 times every day, depending on the product Common side effects may include difficulty sleeping, stomach upset, headache and increased irritability. Many people experience side effects for the first few days of taking theophylline, and then the side effects decrease or disappear. If side effects continue or worsen, notify your doctor. Notify your doctor if you have a fever of 100 degrees F or more for 24 hours. May need a blood test to monitor levels in the blood. This information has been approved by Ronina Covar, MD and Ann Mullen, RN, MSN, CNS, AE-C (December, 2012).