Theophylline

Key facts

• Theophylline is a bronchodilator, a methylxanthine chemically related to caffeine, used for asthma and COPD when other inhaled treatments are not enough.
• Taken as a tablet, usually once or twice daily; doses are individualised because the gap between a helpful blood level and a toxic one is narrow.
• Regular blood tests are needed to measure your theophylline level: too much can cause seizures or dangerous heart rhythms, and too little will not control symptoms.
• Seek urgent care for persistent vomiting, a fast or irregular heartbeat, tremor, confusion, or a seizure.

What theophylline treats

Theophylline treats asthma and chronic obstructive pulmonary disease (COPD) as an add-on when inhaled bronchodilators and steroids do not fully control symptoms. It is used less often today because inhaled treatments generally work as well with fewer side effects, but it remains an option when inhaler technique or access is a barrier.

How theophylline works

Theophylline relaxes the smooth muscle around the airways, widening them, and mildly stimulates the breathing centre in the brain. It works partly by blocking enzymes called phosphodiesterases and by blocking adenosine receptors, which together reduce airway inflammation and improve airflow.

Before you take it

• Tell your prescriber about heart rhythm problems, seizures, liver disease, an overactive thyroid, or a peptic ulcer.
• Smoking speeds up how quickly the body clears theophylline, so doses often differ between smokers and non-smokers, and stopping smoking can push levels into the toxic range.
• Many common drugs change theophylline levels, including some antibiotics such as ciprofloxacin and erythromycin, antifungals, and other asthma medicines; always tell your prescriber about any new medicine.
• Large amounts of caffeine can add to side effects such as tremor and a racing heart.

Side effects

Common effects include nausea, headache, tremor, difficulty sleeping, and a fluttering or racing heartbeat.

Stop and seek urgent medical care for any of these:

• Persistent vomiting.
• Chest pain or a fast, irregular heartbeat.
• Seizures or confusion.
• Severe tremor or agitation.

Safety essentials

• Theophylline has a narrow therapeutic index: blood levels must be checked periodically, and again whenever your dose, an illness, or an interacting medicine changes, because toxic levels can cause seizures and life-threatening heart rhythms.
• Tell every prescriber and pharmacist that you take theophylline, since it interacts with many antibiotics, antifungals, and other asthma drugs, and even quitting smoking can push your level too high.
• Report nausea, tremor, or a racing heart promptly, since these can be early signs that your level is rising before more serious toxicity develops.

This page is educational and does not replace advice from a doctor or pharmacist who knows your health history.