The Asthma Center

Methylxanthines (Theophyllines)

Methylxanthines (theophyllines) are medications with some pharmacological effects similar to caffeine. This type of medication relaxes and opens constricted bronchi. Because they help you "open up" and breathe easier, these medications are considered bronchodilators.


Brand Name Active Ingredient Formulation
Theo-24® theophylline 100, 200, 300, 400mg capsules*
Uniphyl® theophylline 400, 600mg tablets*
theophylline generic theophylline 100, 125, 200, 300mg tablets*

* sustained release


Theophylline preparations can be taken by mouth as a pill, capsule, or liquid or can be sprinkled onto food. Your physician must determine the correct dosage of theophylline for you. This correct dosage is based primarily on your weight, age and ultimately on your theophylline blood level.

Factors that influence this level include additional medical problems (such as congestive heart failure and liver disease), concurrent medications, high fevers, certain viral infections and cigarette smoking. The administration of theophylline is undertaken with great care, since theophylline can produce many side effects.

Risks and Precautions

Theophylline best controls asthmatic symptoms when a steady blood level of theophylline is maintained. Time-release preparations have been developed which release medication steadily into the bloodstream over 6, 8, 12 or more hours. These longer-acting preparations allow you to take a pill or capsule 1 or 2 times a day and maintain the proper amount of theophylline in the body over a 24 hour period. Longer acting theophyllines have been particularly effective in controlling nighttime asthma.

Although physicians can estimate the proper theophylline dosage, many factors influence the way the body metabolizes (breaks down and eliminates) this medication. Currently, theophylline blood levels are the only method of determining whether the "right or effective level" has been achieved. This level should be within the therapeutic range (10 to 20 micrograms per mL of plasma). Theophylline blood levels should be checked periodically when you are on daily theophylline medications.

Other medications (e.g. erythromycin, Biaxin®, Cipro®, and Tagamet®) can change the way your body metabolizes theophylline. Some drug interactions can lead to elevated or "toxic levels" of theophylline. Elevated theophylline levels can cause extreme headaches, stomach aches, diarrhea, seizures, heart rhythm irregularities, irritability and tremors.

At times, you may have a high serum level of theophylline and no adverse symptoms. However you can possibly experience the following adverse effects even at "normal" serum levels:

  • Gastrointestinal symptoms: stomach ache, nausea, vomiting, diarrhea
  • Nervous system symptoms: headache, irritability, difficulties concentrating at work or in school, insomnia, tremors, convulsions
  • Cardiac symptoms: fast heart rate, palpitations, irregular heart rate