Drug & supplement interaction

Green Tea + Ephedrine, Phenobarbital, Theophylline

Ephedrine, Phenobarbital, Theophylline brand name: Tedral.

Major Interaction
Medically reviewed by · Updated September 2026
The bottom line Major

Ephedrine, Phenobarbital, Theophylline falls into 4 drug categories that Green Tea can interact with; the most serious is rated major. Theoretically, concomitant use might increase the risk for stimulant adverse effects.

Read the full interaction report
SeverityMajor
LikelihoodProbable
Interactions4
EvidenceD
What do Severity, Likelihood & Evidence mean?
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Interaction report

Green Tea and Ephedrine, Phenobarbital, Theophylline

These two interact in 4 distinct ways. Each one is explained separately below.

Why Are There 4 Interactions?

Green Tea interacts with whole categories of medication. Ephedrine, Phenobarbital, Theophylline falls into 4 of those categories, so it can interact with Green Tea in 4 different ways. We’ve listed each one below — your overall risk is driven by the most serious of them (Major).

Major

EPHEDRINE

1 of 4
Theoretically, concomitant use might increase the risk for stimulant adverse effects.
Green tea contains caffeine. There is evidence that using ephedrine with caffeine might increase the risk of serious life-threatening or debilitating adverse effects such as hypertension, myocardial infarction, stroke, seizures, and death.
Severity Major Likelihood Probable Evidence D

Interaction has not been documented in well-controlled studies, however, the interaction has been demonstrated in some small human studies or in controlled animal studies in conjunction with multiple case reports..

Dr. Brian Staiger, PharmD, BCPS
Dr. Brian Staiger explains PharmD, Clinical Pharmacist

Here's the thing to watch with Tedral: it contains ephedrine, a stimulant, plus theophylline, which is closely related to caffeine. Green tea naturally carries caffeine too, so you're really stacking stimulant on top of stimulant. That combination can push your heart and blood pressure harder than you'd want. People may feel a racing or pounding heartbeat, jitteriness, trouble sleeping, headache, or shakiness, and in rare cases it has been tied to very serious problems like dangerous blood pressure spikes or heart rhythm issues.

This warning leans heavily on caffeine plus ephedrine reports, so it's more anecdotal than rock-solid, and a casual cup of green tea is far gentler than concentrated extract pills. Still, please check with your pharmacist or doctor before pairing them, especially with the extract form.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Haller CA, Benowitz NL. Adverse cardiovascular and central nervous system events associated with dietary supplements containing ephedra alkaloids. N Engl J Med 2000;343:1833-8. PubMed
  2. Kockler DR, McCarthy MW, Lawson CL. Seizure activity and unresponsiveness after hydroxycut ingestion. Pharmacotherapy 2001;21:647-51.. PubMed
Moderate

STIMULANT DRUGS

2 of 4

Why this applies to Ephedrine, Phenobarbital, Theophylline

Ephedrine, Phenobarbital, Theophylline falls under STIMULANT DRUGS — the group Green Tea interacts with.

Theoretically, concomitant use might increase stimulant adverse effects.
Green tea contains caffeine. Due to the central nervous system (CNS) stimulant effects of caffeine, concomitant use with stimulant drugs can increase the risk of adverse effects.
Severity Moderate Likelihood Probable Evidence C

Interaction has not been documented in well-controlled studies, however, the interaction has been demonstrated in some small human studies or in controlled animal studies in conjunction with multiple case reports..

Dr. Brian Staiger, PharmD, BCPS
Dr. Brian Staiger explains PharmD, Clinical Pharmacist

Here's the simple version: green tea naturally contains caffeine, and your Tedral combo already includes two stimulants of its own (ephedrine and theophylline). Stacking caffeine on top can pile on the same kinds of effects, so you might feel jittery, have a racing or pounding heartbeat, trouble sleeping, shakiness, or feel anxious and on edge.

This is a theoretical concern based mostly on expert opinion, not strong studies, so a normal cup or two of green tea probably won't cause trouble for most people. The bigger worry is concentrated green tea extract pills, which deliver a lot more caffeine. Theophylline can be touchy at higher levels, so if you notice your heart pounding or feel wired, check in with your pharmacist or doctor before changing anything.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Institute of Medicine. Caffeine for the Sustainment of Mental Task Performance: Formulations for Military Operations. Washington, DC: National Academy Press, 2001. Available at: http://books.nap.edu/books/0309082587/html/index.html. DOI
Moderate

THEOPHYLLINE

3 of 4

Ephedrine, Phenobarbital, Theophylline also falls under THEOPHYLLINE.

Theoretically, green tea might increase the levels and adverse effects of theophylline.
Green tea contains caffeine. Large amounts of caffeine might inhibit theophylline metabolism.
Severity Moderate Likelihood Probable Evidence B

Interaction has not been documented in well-controlled studies, however, the interaction has been demonstrated in some small human studies or in controlled animal studies in conjunction with multiple case reports..

Dr. Brian Staiger, PharmD, BCPS
Dr. Brian Staiger explains PharmD, Clinical Pharmacist

Here's the thing to keep an eye on with Tedral: it contains theophylline, which your liver clears using the same enzymes that handle caffeine. Green tea has caffeine too, and in larger amounts that caffeine may slow down how fast theophylline is broken down. The result is that theophylline can build up a little higher than expected.

Why does that matter? Theophylline already has a narrow safety window. When levels creep up, you may notice jitteriness, a racing or pounding heart, nausea, trouble sleeping, or feeling shaky. A cup or two of green tea now and then likely won't do much, but concentrated green tea extracts or heavy daily intake are more of a concern. This is based on the caffeine effect rather than strong trials, so don't panic, just check in with your pharmacist or doctor before adding green tea supplements.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Carrillo JA, Benitez J. Clinically significant pharmacokinetic interactions between dietary caffeine and medications. Clin Pharmacokinet 2000;39:127-53. PubMed
Moderate

PHENOBARBITAL (Luminal)

4 of 4
Theoretically, green tea might reduce the effects of phenobarbital and increase the risk for convulsions.
Green tea contains caffeine. Animal research suggests that caffeine can decrease the anticonvulsant activity of phenobarbital. The exact mechanism of this interaction is unclear.
Severity Moderate Likelihood Possible Evidence D

Interaction has been documented in animal or in lab research, or the interaction has been documented in humans but is limited to case reports or conflicting clinical research exists.

Dr. Brian Staiger, PharmD, BCPS
Dr. Brian Staiger explains PharmD, Clinical Pharmacist

This older combination product (Tedral) pairs phenobarbital, a barbiturate that calms seizures, with theophylline and ephedrine for breathing. The interaction here centers on the phenobarbital piece. Green tea contains caffeine, and in animal studies caffeine seemed to blunt phenobarbital's seizure-calming activity. In theory, that could make phenobarbital a little less effective and, in someone using it for seizures, slightly raise the chance of a seizure breaking through.

I want to be honest with you: this is theoretical and based only on lab and animal data, so I wouldn't lose sleep over a normal cup of tea. Concentrated green tea extracts (with more caffeine) are a bigger question mark. Since this drug needs steady levels to work, just run your green tea habit by your pharmacist or doctor before adding supplements.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Gasior, M., Borowicz, K., Buszewicz, G., Kleinrok, Z., and Czuczwar, S. J. Anticonvulsant activity of phenobarbital and valproate against maximal electroshock in mice during chronic treatment with caffeine and caffeine discontinuation. Epilepsia 1996;37(3 PubMed
  2. Jankiewicz, K., Chroscinska-Krawczyk, M., Blaszczyk, B., and Czuczwar, S. J. [Caffeine and antiepileptic drugs: experimental and clinical data]. Przegl.Lek. 2007;64(11):965-967.
  3. Chroscinska-Krawczyk, M., Jargiello-Baszak, M., Walek, M., Tylus, B., and Czuczwar, S. J. Caffeine and the anticonvulsant potency of antiepileptic drugs: experimental and clinical data. Pharmacol.Rep. 2011;63(1):12-18. PubMed

What These Ratings Mean

Every interaction above is graded three ways — here’s the key to each label.

Severity how clinically significant the interaction is
Major

Clinically significant. Avoid the combination, or use only under close professional supervision.

Moderate

Usually worth avoiding or managing — may need monitoring, a dose change, or timing apart.

Minor

Generally not serious. Be aware of it and mention it to your pharmacist.

Likelihood how strong the evidence is that the interaction actually happens in people
  • LikelyWell-controlled human studies have demonstrated the likely existence of this interaction.
  • ProbableInteraction has not been documented in well-controlled studies, however, the interaction has been demonstrated in some small human studies or in controlled animal studies in conjunction with multiple case reports.
  • PossibleInteraction has been documented in animal or in lab research, or the interaction has been documented in humans but is limited to case reports or conflicting clinical research exists.
  • UnlikelyInteraction has been demonstrated in animal or in lab research but has been shown not to occur in humans.
Evidence the quality of the studies behind the rating (graded A–D)
  • AHigh-quality meta-analysis (quantitative systematic review).
  • BCase-control study.
  • CConsensus.
  • DAnecdotal evidence.

These ratings are for information only. Never start, stop, or otherwise change your therapy before speaking with your provider.

Keep it in perspective

Green Tea Also Interacts With Other Medications

Green Tea has 12 major, 905 moderate, 375 minor known drug interactions in our database — the Ephedrine, Phenobarbital, Theophylline one above is among them. If you take anything else, check it against the full list below.

Major 12 Moderate 905 Minor 375 No known interaction 1,538 (incl. Ephedrine, Phenobarbital, Theophylline)
Taking anything else?

Check Another of Your Medications Against Green Tea

Covers the 2,830 medications we’ve checked against Green Tea. Pick one to open its full report.

From our Q&A

Questions About Green Tea or Ephedrine, Phenobarbital, Theophylline

These are real questions from readers, answered by the pharmacists at HelloPharmacist — written by a person, not generated from a database. Each one covers Green Tea or Ephedrine, Phenobarbital, Theophylline, not necessarily both, but if one is close to what you were about to ask it will usually go further than a database entry can:

Not quite your question? Ask our pharmacists directly — it is free, there is no account required, and answers usually come back within 24 hours.

Everything else you take

See Every Supplement That Interacts With Ephedrine, Phenobarbital, Theophylline

This page covers Green Tea only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Ephedrine, Phenobarbital, Theophylline page lists 184 supplements it has a documented interaction with, worst first, each one explained.

The most serious there right now: 1,4-butanediol (major), Activated Charcoal (major), Beer (major), Black Tea (major) and Caffeine (major).

By severity: 22 major · 140 moderate · 22 minor.

Open the Ephedrine, Phenobarbital, Theophylline interaction page

One more smart check

Taking Green Tea as Part of a Dietary Supplement Product? Check It for Interactions

We hold 9,084 real supplement products containing Green Tea, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Green Tea. Your product may carry other ingredients that interact with Ephedrine, Phenobarbital, Theophylline too, on top of Green Tea — and those would not show on this page. Find your product and we’ll check every ingredient on its label:

How much people look this up

Where Green Tea and Ephedrine, Phenobarbital, Theophylline Sit Against Everything Else

Out of every supplement and medication people look up on HelloPharmacist, here is where these two land this week — and which way each has been moving.

Supplement Green Tea
Top 5%

#23 of 1,452 supplements looked up here in the last 7 days

29 days ago today
Medication Ephedrine, Phenobarbital, Theophylline
Top 5%

#72 of 2,830 medications looked up here in the last 7 days

29 days ago today

Position among everything looked up on this site, not a measure of how commonly either one is used or how important it is. A supplement can climb this list because of a news story. It counts every request to the page, automated ones included, and nothing here identifies anyone.

Supplement

About Green Tea

What is Green Tea?

Green Tea
  • Antioxidant support
  • Weight loss
  • Heart health
  • Mental alertness
  • Cancer risk reduction

Green tea is a popular beverage rich in antioxidants called catechins, and drinking it in normal amounts is considered safe for most people. Concentrated green tea extracts are a different story—they may help modestly with weight or heart health for some, but high doses have been linked to rare liver problems. Talk to your pharmacist or doctor before taking green tea supplements, especially if you have liver concerns or are pregnant.

Read the full Green Tea monograph & all interactions
Keep checking

Other Drugs & Green Tea

Browse every other medication we’ve checked against Green Tea — both the ones with a known interaction and the ones without. Select any drug for the full detail.

12Major
905Moderate
375Minor
1,537No known interaction
12 Major 905 Moderate 375 Minor 1,537 No interaction
Major

12 interactions

Moderate

905 interactions

Showing 60 of 905 moderate interactions — see all 905 on the Green Tea page.

Minor

375 interactions

Showing 60 of 375 minor interactions — see all 375 on the Green Tea page.

No interaction 1,537 drugs checked — show the list

We also checked Green Tea against these medications and found no known interaction in our sources. Open any page to confirm.

Showing the 60 most looked-up of 1,537 medications checked with no known interaction — see the full Green Tea list.

See the full Green Tea interactions page
See every supplement checked against Ephedrine, Phenobarbital, Theophylline, ranked by severity
Sources

Sources & How We Checked

Interaction details are evidence-graded and sourced from the Natural Medicines database. The medication overview comes from MedlinePlus.

Content is written and reviewed by licensed HelloPharmacist pharmacists. See our data sources and editorial standards for how this information is built and checked.

Parts of this content are provided by the Therapeutic Research Center, LLC.

DISCLAIMER: Currently this does not check for drug-drug interactions. This is not an all-inclusive comprehensive list of potential interactions and is for informational purposes only. Not all interactions are known or well-reported in the scientific literature, and new interactions are continually being reported. Input is needed from a qualified healthcare provider including a pharmacist before starting any therapy. Application of clinical judgment is necessary.

© 2021 Therapeutic Research Center, LLC

Keep exploring
Green Tea monograph › Uses, safety, and every drug interaction in one place Ephedrine, Phenobarbital, Theophylline supplement interactions › Every supplement checked against Ephedrine, Phenobarbital, Theophylline, ranked by severity Supplement interaction checker › Check any supplement or product against your medications Browse medications A–Z › Every drug we've checked against herbs & supplements Ask a pharmacist › Free, personal answer from our licensed team
Pharmacist Counseling Corner

Taking Green Tea and Ephedrine, Phenobarbital, Theophylline Together: Common Questions

Can you take Green Tea with Ephedrine, Phenobarbital, Theophylline?
This is rated a major interaction, so the combination is best avoided unless your doctor or pharmacist has specifically told you otherwise. Read the full details on this page and confirm with your pharmacist before combining them.
Why are there 4 interactions listed for Green Tea and Ephedrine, Phenobarbital, Theophylline?
Ephedrine, Phenobarbital, Theophylline belongs to more than one drug category, and Green Tea interacts with each of those categories a little differently. We list every one so nothing is missed — your overall risk is driven by the most serious of them.
How serious is the Green Tea and Ephedrine, Phenobarbital, Theophylline interaction?
We rate it Major. This is a clinically significant combination that is generally best avoided, or used only under the direct supervision of your physician or pharmacist.

Written and reviewed by the HelloPharmacist editorial staff. Our editorial policy

Still Have a Question About Ephedrine, Phenobarbital, Theophylline and Green Tea?

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This information is for education only and is not a substitute for professional medical advice. Always check with your pharmacist or doctor before starting, stopping, or combining supplements and medications.