The short answer
Caffeine can raise theophylline exposure and add unwanted stimulation. Review regular caffeine intake before adding a concentrated product.
What this answer covers
Caffeine in supplements and drinks; total dose and pattern matter. Oral and intravenous theophylline studies are distinguished.
- Supplement or preparation
- Caffeine
- Medication ingredient
- theophylline
What the human studies found
Small studies found slower theophylline removal with caffeine. One used regular instant coffee and oral drug; another used caffeine tablets with an intravenous infusion. These support a level-related interaction, not a prediction that every user will develop an abnormal heart rhythm or seizure.
Count the whole daily intake
Include coffee, tea, energy drinks and supplements in the amount you discuss with the prescriber. Caffeine sensitivity varies, and general population limits are not a personalized limit for someone taking theophylline.
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
Human studies support reduced theophylline clearance with caffeine. Conditional interaction concern is supported, but exact QT prolongation, arrhythmia and seizure rates for this pair are not established; the label documents serious theophylline toxicity.
- Exact scope
- Caffeine in supplements and drinks; total dose and pattern matter. Oral and intravenous theophylline studies are distinguished. 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 validated caffeine limit or separation interval. The infusion study used 900 mg caffeine daily; coffee findings do not define every capsule exposure.
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: 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: 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.
Source 4: original human study
pubmed.ncbi.nlm.nih.gov · Source check Sep 10, 2026
Population: Eight healthy volunteers in open crossover study.
Theophylline steady-state concentration rose 23% and AUC 40%; apparent clearance fell 29%.
How this applies: Only the named drug, preparation, route and measured endpoints apply.
High caffeine exposure and intravenous drug, not a recommended intake or a direct oral-tablet outcome estimate. No arrhythmia or seizure outcome established.
Source 5: 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.
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: 6c2fd6775b6778b4
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.