The short answer
Guarana can add caffeine exposure while you take theophylline. Review the product and total caffeine intake before using it.
What this answer covers
Paullinia cupana, particularly oral seed preparations; whole seed, extracts and energy blends have different caffeine amounts.
- Supplement or preparation
- Paullinia cupana
- Medication ingredient
- theophylline
Guarana is a caffeine source
A seed powder or extract can contribute to daily stimulant intake. The amount of guarana on a label does not by itself give the total caffeine dose, especially in products with other caffeine ingredients.
How the interaction is inferred
Small human coffee research found slower theophylline clearance with caffeine. That supports caution with caffeine-containing guarana, but is not a direct study of the seed product or a measured seizure risk.
Check existing heart problems
EMA’s guidance for specified guarana seed medicines advises against use with cardiovascular conditions such as hypertension or arrhythmias. Discuss those conditions and the complete product with the prescriber.
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
Conditional concern follows from guarana caffeine content and human caffeine-theophylline exposure findings. Exact guarana-pair QT prolongation, arrhythmia and seizure outcomes are unproven, despite known theophylline toxicity and guarana cardiovascular precautions.
- Exact scope
- Paullinia cupana, particularly oral seed preparations; whole seed, extracts and energy blends have different caffeine amounts. 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 direct guarana-theophylline clinical trial or universal seed-to-caffeine conversion found.
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
ema.europa.eu · Source check Sep 10, 2026
Population: People considering the specified supplement.
HMPC assesses oral dried powdered guarana seeds for traditional fatigue use; cardiovascular contraindications apply to specified seed medicines.
How this applies: Supplement-only context; explicit medication and preparation bridge required.
Not proof of exact-drug combination risk or equivalence to caffeine capsules or multi-ingredient energy products.
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: d791ec8b390db021
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.