Prescription ·Strong evidence ·Reviewed May 2026
Theophylline is an oral methylxanthine bronchodilator used in selected asthma and COPD patients when other therapies are insufficient or unavailable. It has a narrow therapeutic index, variable clearance, and serious toxicity risks including nausea, tachyarrhythmias, seizures, and death, so serum level monitoring and interaction review are essential.
The bottom line
Evidence rating strong. Most-documented uses: maintenance bronchodilation in selected asthma patients, maintenance treatment adjunct in copd, reduction of nocturnal bronchospasm in some patients. 4 sources indexed (1980–2026), with 4 interaction records on file.
Core mechanism
Theophylline inhibits phosphodiesterase nonselectively, antagonizes adenosine receptors, increases catecholamine release, and may enhance diaphragmatic contractility and anti-inflammatory signaling at lower concentrations. Clearance is mainly hepatic through CYP1A2 with contributions from CYP2E1 and CYP3A pathways, so smoking status, fever, liver disease, heart failure, age, and interacting drugs or botanicals can markedly change levels.1,2
Use the same product and take consistently with regard to food because extended-release absorption varies by formulation. Avoid sudden changes in caffeine intake and smoking status without reassessing serum concentrations.
Nutrients this medication can lower over time, and what to replace.
Theophylline exposure has been associated with reduced pyridoxal phosphate status and may increase neurologic vulnerability in susceptible patients.
Caffeinated green tea extract can add to methylxanthine stimulation and may worsen tremor, insomnia, tachycardia, nausea, and arrhythmia risk.
Recommendation: Avoid high-caffeine extracts and keep caffeine intake stable; check theophylline levels if symptoms occur.
Vitamin B6 may help correct low pyridoxal phosphate status associated with long-term theophylline therapy.
Recommendation: Use standard supplemental doses unless a clinician directs higher therapy; persistent neurologic symptoms require theophylline level assessment.
St. John's Wort may induce drug-metabolizing pathways and make theophylline exposure less predictable.
Recommendation: Avoid starting or stopping St. John's Wort without clinician-supervised theophylline level monitoring.
Theophylline can worsen insomnia and may counter sleep-promoting strategies such as melatonin.
Recommendation: Address theophylline timing, serum level, and caffeine intake before escalating sleep supplements.
Numbered references. Citations throughout the page link here.
Guidelines emphasize inhaled bronchodilators and note safety limitations of methylxanthines.
Review details clinical toxicity and the importance of prompt recognition and serum level management.
Clinical data reported reduced pyridoxal phosphate measures during theophylline therapy, supporting monitoring when neurologic symptoms or poor intake are present.
Labeling describes variable clearance, therapeutic drug monitoring, toxicity, and numerous clinically important interactions.
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