Theophylline is a drug that must be closely monitored. Patients must have just the right amount of the drug in their bloodstream – enough to effectively treat their condition, but not so much that it becomes toxic.

Various medical conditions alter the rate at which theophylline is cleared from the body. For this reason, patients with certain conditions may either be disqualified from using the drug or need to have their dosages adjusted.

The following conditions pose concerns regarding theophylline use:

• Liver disease. Can decrease the rate that theophylline is removed from the body, because theophylline is metabolized by the liver. Therefore, impairment of this organ can lead to toxic levels of the medication in the bloodstream.
  
  
• Stomach ulcer.
  
  
• Seizures.
  
  
• Glaucoma.
  
  
• Diabetes.
  
  
• Kidney disease.
  
  
• Blood vessel disease.
  
  
• High blood pressure (hypertension).
  
  
• Heart disease, or any heart condition. Can cause side effects of irregular and rapid heartbeat (arrhythmia and palpitations).
  
  
• Heart failure. Can decrease the rate that theophylline is removed from the body, increasing the risk of side effects or overdose.
  
  
• Pneumonia. Can decrease the rate that theophylline is removed from the body, increasing the risk of side effects or overdose.
  
  
• Thyroid condition. Can increase the rate that theophylline is removed from the body, and thus require a higher dose of the medication.
  
  
• Viral infection and vaccination. Can decrease the rate that theophylline is removed from the body, increasing the risk of side effects or overdose.
  
  
• Gastroesophageal reflux disease (GERD). Theophylline relaxes the esophagus near the opening to the stomach. This can result in heartburn (acid reflux) if stomach acid travels into the esophagus. Some people – especially those with asthma – may experience breathing problems as a result of increased airway obstruction caused by acid reflux.

Those who smoke may need to take larger doses of theophylline, as tobacco smoke increases the rate at which the medication is cleared from the body. Patients are encouraged to discuss concerns with their physician. Also, those taking theophylline should not stop or start smoking without first consulting a physician.