Drug & supplement interaction

Oolong 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 Oolong 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?
Know someone taking this? Share
Facebook Post Reddit Email
On this page
Interaction report

Oolong Tea and Ephedrine, Phenobarbital, Theophylline

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

Why Are There 4 Interactions?

Oolong Tea interacts with whole categories of medication. Ephedrine, Phenobarbital, Theophylline falls into 4 of those categories, so it can interact with Oolong 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.
Oolong 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. Tell patients to avoid taking caffeine with ephedrine and other stimulants.
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 combines ephedrine (a stimulant) and theophylline, and both can rev up your heart and nervous system on their own. Oolong tea adds caffeine to that mix, which is another stimulant. So you're essentially stacking stimulants on top of stimulants.

When you pile these together, you raise the odds of feeling jittery, having a racing or pounding heartbeat, trouble sleeping, anxiety, and higher blood pressure. In serious cases, the combination has been linked to dangerous events like very high blood pressure or heart rhythm problems. The evidence here is mostly anecdotal, but because the risk is real, I'd keep caffeine like oolong tea to a minimum and check with your pharmacist or doctor about what's safe for you.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Vahedi K, Domingo V, Amarenco P, Bousser MG. Ischemic stroke in a sportsman who consumed MaHuang extract and creatine monohydrate for bodybuilding. J Neurol Neurosurg Psychiatr 2000;68:112-3.
  2. 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
  3. 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 Oolong Tea interacts with.

Theoretically, concomitant use might increase stimulant adverse effects.
Oolong tea contains caffeine. Due to the CNS stimulant effects of the caffeine constituent of oolong tea, 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: oolong tea has caffeine in it, and your Tedral combo already contains two stimulants of its own. Ephedrine works a lot like adrenaline, and theophylline is chemically related to caffeine and revs up the same systems. So when you stack tea on top, you're essentially layering stimulant on stimulant.

What that can feel like is a faster or pounding heartbeat, jitteriness, trembling hands, trouble sleeping, or feeling wired and anxious. This is an expert-opinion, theoretical caution rather than something proven in studies, so a single cup probably won't cause trouble for most people. But theophylline has a narrow safe range, so if you drink tea regularly or feel any of those symptoms, please check with your pharmacist or doctor first.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. DiPiro JT, Talbert RL, Yee GC, et al; eds. Pharmacotherapy: A pathophysiologic approach. 4th ed. Stamford, CT: Appleton & Lange, 1999.
  2. 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, oolong tea might increase the levels and adverse effects of theophylline.
Oolong tea contains caffeine. Caffeine decreases theophylline clearance 23% to 29%.
Severity Moderate 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 keep in mind with Tedral: it contains theophylline, and your body clears that drug partly using the same pathways that handle caffeine. Oolong tea brings its own caffeine to the party, which can slow theophylline's exit a bit (studies suggest clearance drops roughly 23% to 29%). That means theophylline levels could creep up.

Theophylline already has a narrow safety window, so even a small bump can show up as jitteriness, a racing or pounding heartbeat, nausea, trouble sleeping, or feeling wired. Honestly, this is a theoretical concern based on how caffeine behaves, not hard proof, and an occasional cup is unlikely to cause trouble. Still, if you drink oolong regularly, mention it to your pharmacist or doctor before changing anything.

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, oolong tea might reduce the effects of phenobarbital and increase the risk for convulsions.
Oolong 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 combo product includes phenobarbital, a sedative used to calm the brain and help prevent seizures. The concern here is the caffeine in oolong tea. Caffeine is a mild stimulant, and in animal studies it appeared to work against phenobarbital's seizure-calming effect. In plain terms, a lot of caffeine could in theory make phenobarbital a little less effective at doing its job.

I want to be honest: this is based on lab and animal data only, so it's quite weak evidence. A cup or two of oolong tea is unlikely to be a problem for most people. Where I'd pay more attention is large amounts of tea or concentrated caffeine. Since this is a seizure medicine, it's worth a quick chat with your pharmacist or doctor before changing your habits.

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

Oolong Tea Also Interacts With Other Medications

Oolong Tea has 7 major, 518 moderate, 126 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 7 Moderate 518 Minor 126 No known interaction 2,179 (incl. Ephedrine, Phenobarbital, Theophylline)
Taking anything else?

Check Another of Your Medications Against Oolong Tea

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

Everything else you take

See Every Supplement That Interacts With Ephedrine, Phenobarbital, Theophylline

This page covers Oolong 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 Oolong Tea as Part of a Dietary Supplement Product? Check It for Interactions

We hold 75 real supplement products containing Oolong Tea, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Oolong Tea. Your product may carry other ingredients that interact with Ephedrine, Phenobarbital, Theophylline too, on top of Oolong 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 Oolong 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 Oolong Tea
Steady interest

#1,066 of 1,452 supplements looked up here in the last 7 days

29 days ago today
Medication Ephedrine, Phenobarbital, Theophylline
Top half

#1,084 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 Oolong Tea

What is Oolong Tea?

  • Weight management
  • Mental alertness and energy
  • Heart health
  • Blood sugar support
  • Antioxidant support

Oolong tea is a traditional partially oxidized tea made from the same plant as green and black tea, and it provides caffeine and plant antioxidants. As a beverage it is generally considered safe for most healthy adults in moderate amounts, but evidence for specific health benefits like weight loss or blood sugar control is limited. If you have heart, blood pressure, or caffeine-sensitivity concerns, talk with your pharmacist or doctor.

Read the full Oolong Tea monograph & all interactions
Keep checking

Other Drugs & Oolong Tea

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

7Major
518Moderate
126Minor
2,178No known interaction
7 Major 518 Moderate 126 Minor 2,178 No interaction
Major

7 interactions

Moderate

518 interactions

Showing 60 of 518 moderate interactions — see all 518 on the Oolong Tea page.

Minor

126 interactions

Showing 60 of 126 minor interactions — see all 126 on the Oolong Tea page.

No interaction 2,178 drugs checked — show the list

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

Showing the 60 most looked-up of 2,178 medications checked with no known interaction — see the full Oolong Tea list.

See the full Oolong 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
Oolong 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 Oolong Tea and Ephedrine, Phenobarbital, Theophylline Together: Common Questions

Can you take Oolong 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 Oolong Tea and Ephedrine, Phenobarbital, Theophylline?
Ephedrine, Phenobarbital, Theophylline belongs to more than one drug category, and Oolong 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 Oolong 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 Oolong Tea?

Our pharmacists answer your medication & supplement questions — free.

Ask a pharmacist

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.