The short answer
Check the caffeine content and extract strength before using green tea leaf extract with theophylline. The exact extract combination has not been adequately tested.
What this answer covers
Camellia sinensis leaf extract; concentrated extracts, decaffeinated extracts and brewed tea are different exposures.
- Supplement or preparation
- Camellia Sinensis Leaf Extract
- Medication ingredient
- theophylline
Why the ingredient list matters
Green tea leaf extracts vary in caffeine and catechins. Ask for the caffeine amount per serving and count all servings. A decaffeinated extract should not automatically inherit caffeine-related claims.
What the drug evidence means
Coffee reduced theophylline clearance in a small human study. That supports reviewing caffeine-containing extracts, but does not measure the effect of this particular green tea product.
Separate the extract risks
Uncommon liver injury has been reported mainly with concentrated green tea products. This is a separate supplement concern, not proof that theophylline and green tea together cause liver injury.
Use a monitored plan
Keep theophylline dosing and formulation consistent with your prescription. Tell the prescriber about supplement starts, stops and dose changes. Separating products by a few hours has not been shown to prevent changes in drug clearance, and a study dose is not a recommended supplement dose.
Recognize possible toxicity
Contact the prescriber promptly for repeated nausea or vomiting, new insomnia or tremor after a product change. A seizure, fainting or a sustained rapid or irregular heartbeat needs urgent assessment. A blood theophylline measurement may be needed; symptoms alone cannot determine the level.
Evidence and practical considerations
Side effects & toxicity
Concern is conditional on caffeine exposure and extract composition. Caffeine findings support a possible level or stimulation issue, while extract-related liver signals are supplement-only evidence rather than proven combined injury.
- Exact scope
- Camellia sinensis leaf extract; concentrated extracts, decaffeinated extracts and brewed tea are different exposures. with Exact theophylline anhydrous extended-release tablets and oral solution. Exact RxNorm IN10438. Oral anhydrous theophylline formulations distinguished; intravenous and aminophylline study exposures are identified separately.
- Medication form and route
- oral
- Timing or duration
- Source-specific single-dose, repeated-dose and observational exposures distinguished.
What remains uncertain
- No exact extract-theophylline trial identified. Coffee cannot determine the effect of a decaffeinated catechin extract or justify a universal high-dose threshold.
Factors that may matter: preparation and plant part; clinical indication; dose; other medicines; baseline alertness.
Read the supporting source summaries
Source 1: current product label
dailymed.nlm.nih.gov · Source check Sep 10, 2026
Population: People prescribed theophylline.
Variable clearance, narrow therapeutic range and serum concentration monitoring; toxicity can include arrhythmias and seizures; label specifically warns about St John’s wort and ephedrine.
How this applies: Exact RxNorm IN10438. Oral anhydrous theophylline formulations distinguished; intravenous and aminophylline study exposures are identified separately.
No universal supplement dose, interval, event rate or untested formulation equivalence.
Source 2: current product label
dailymed.nlm.nih.gov · Source check Sep 10, 2026
Population: People prescribed theophylline.
Variable clearance, narrow therapeutic range and serum concentration monitoring; toxicity can include arrhythmias and seizures; label specifically warns about St John’s wort and ephedrine.
How this applies: Exact RxNorm IN10438. Oral anhydrous theophylline formulations distinguished; intravenous and aminophylline study exposures are identified separately.
No universal supplement dose, interval, event rate or untested formulation equivalence.
Source 3: official supplement guidance
nccih.nih.gov · Source check Sep 10, 2026
Population: People considering the specified supplement.
Tea contains caffeine; concentrated extracts differ from beverages and have been linked to uncommon liver injury and increased blood pressure.
How this applies: Supplement-only context; explicit medication and preparation bridge required.
Does not establish a respiratory medication interaction or identical caffeine content across extracts.
Source 4: official supplement guidance
fda.gov · Source check Sep 10, 2026
Population: People considering the specified supplement.
Caffeine can cause palpitations, anxiety, sleep problems and other effects; sensitivity depends partly on medicines and individual factors.
How this applies: Supplement-only context; explicit medication and preparation bridge required.
General adult intake advice does not establish a safe caffeine limit with this medicine.
Source 5: original human study
pubmed.ncbi.nlm.nih.gov · Source check Sep 10, 2026
Population: Six healthy men.
Theophylline clearance fell 23% and half-life rose 32% compared with caffeine deprivation.
How this applies: Human constituent evidence, not a direct study of this whole botanical or variable isoflavone mixture. Only the named drug, preparation, route and measured endpoints apply.
Small pharmacokinetic study; original abstract does not establish arrhythmia, QT or seizure incidence, caffeine capsule equivalence or a protective gap.
Research assessment: · Open full citations ↗
Review and change history
- Publication status
- Published research summary
- Clinical review
- Not yet recorded
| Date | Update |
|---|---|
| Research summary published | |
| Article prepared | |
| Current exact available claims adjudicated using original captures and explicit identity and comparator limits. |
Article revision: e59a4bd299e505fb
This guide brings together the evidence records used by our interaction checker. Each finding retains its own preparation limits, research date, and source summaries.
Full citations require verification. Reading this answer and the source summaries does not.
Taking other supplements or medications?
Use the checker to explore your other combinations. Ask a pharmacist to review the exact products, amounts and medical conditions in your complete list.
Open the interaction checkerInformation, not medical advice. Do not change prescribed treatment based on this guide.