Drug & supplement interaction

Coffee + 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 3 drug categories that Coffee can interact with; the most serious is rated major. Theoretically, concomitant use might increase the risk of stimulant adverse effects.

Read the full interaction report
SeverityMajor
LikelihoodProbable
Interactions3
EvidenceD
What do Severity, Likelihood & Evidence mean?
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Interaction report

Coffee and Ephedrine, Phenobarbital, Theophylline

These two interact in 3 distinct ways. Each one is explained separately below.

Why Are There 3 Interactions?

Coffee interacts with whole categories of medication. Ephedrine, Phenobarbital, Theophylline falls into 3 of those categories, so it can interact with Coffee in 3 different ways. We’ve listed each one below — your overall risk is driven by the most serious of them (Major).

Major

EPHEDRINE

1 of 3
Theoretically, concomitant use might increase the risk of stimulant adverse effects.
Coffee 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 about Tedral: it already contains two stimulants, ephedrine and theophylline. Coffee adds even more stimulation on top because of its caffeine. When you stack stimulants like this, the effects can add up in a way that's hard on your heart and nervous system.

In practice, that means a bigger risk of feeling jittery, a racing or pounding heartbeat, trouble sleeping, anxiety, and higher blood pressure. The reports behind this warning are mostly anecdotal, but the concern is real because both ephedrine and theophylline can push the heart hard, and rarely this combination has been linked to serious events. I'd keep coffee and other caffeine sources low while on Tedral, and talk 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. Shekelle PG, Hardy ML, Morton SC, et al. Efficacy and safety of ephedra and ephedrine for weight loss and athletic performance: a meta-analysis. JAMA 2003;289:1537-45.. PubMed
  4. Kockler DR, McCarthy MW, Lawson CL. Seizure activity and unresponsiveness after hydroxycut ingestion. Pharmacotherapy 2001;21:647-51.. PubMed
Moderate

STIMULANT DRUGS

2 of 3

Why this applies to Ephedrine, Phenobarbital, Theophylline

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

Theoretically, concomitant use might increase stimulant adverse effects.
Coffee 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

This combination product (Tedral) contains a few active pieces, but the one that really matters here is theophylline, along with the decongestant ephedrine. Both are stimulants, and so is the caffeine in your coffee. They all rev up the same systems, so stacking them together can add up. The concern isn't that coffee changes how the medicine is broken down so much as the effects piling on top of each other.

What that can feel like: a racing or pounding heart, jitteriness, shaky hands, trouble sleeping, headache, or an upset stomach. Theophylline in particular has a narrow safety window, so it's worth being thoughtful. This is based mostly on expert opinion rather than hard studies. A morning cup is probably fine for many people, but if you notice these symptoms, talk 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 3

Ephedrine, Phenobarbital, Theophylline also falls under THEOPHYLLINE.

Theoretically, coffee might increase the levels and adverse effects of theophylline.
Coffee contains caffeine, which can increase theophylline levels.
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

This older combo medicine (Tedral) contains theophylline, which is chemically very close to the caffeine in your coffee. Your body actually clears both using the same liver pathway, so when they compete, theophylline can stack up a bit higher than expected. Because theophylline already has a narrow safety window, even small increases can tip you toward jitteriness, a racing or pounding heart, nausea, trouble sleeping, or feeling shaky. The ephedrine piece can add to that stimulant feeling too.

This is mostly a theoretical, dose-related concern, and an occasional cup is unlikely to cause trouble. Still, if you drink coffee daily, mention it to your pharmacist or doctor so they can keep an eye on your levels and symptoms.

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
  2. Sato J, Nakata H, Owada E, et al. Influence of usual intake of dietary caffeine on single-dose kinetics of theophylline in healthy human subjects. Eur J Clin Pharmacol 1993;44:295-8. PubMed
  3. Jonkman JH, Sollie FA, Sauter R, Steinijans VW. The influence of caffeine on the steady-state pharmacokinetics of theophylline. Clin Pharmacol Ther 1991;49:248-55. 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

Coffee Also Interacts With Other Medications

Coffee has 7 major, 467 moderate, 116 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 467 Minor 116 No known interaction 2,240 (incl. Ephedrine, Phenobarbital, Theophylline)
Taking anything else?

Check Another of Your Medications Against Coffee

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

Everything else you take

See Every Supplement That Interacts With Ephedrine, Phenobarbital, Theophylline

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

We hold 716 real supplement products containing Coffee, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Coffee. Your product may carry other ingredients that interact with Ephedrine, Phenobarbital, Theophylline too, on top of Coffee — 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 Coffee 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 Coffee
Top 5%

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

29 days ago today
Medication Ephedrine, Phenobarbital, Theophylline
Steady interest

#2,640 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 Coffee

What is Coffee?

  • Alertness and reducing fatigue
  • Mental focus and concentration
  • Athletic performance
  • Headache relief
  • Weight management

Coffee is a widely consumed beverage made from roasted coffee beans, valued mainly for its caffeine, which boosts alertness and energy. For most healthy adults, moderate coffee intake is generally safe and may have some health benefits, but too much can cause jitteriness, poor sleep, and a faster heartbeat. People who are pregnant, breastfeeding, or sensitive to caffeine should limit their intake and check with a doctor or pharmacist.

Read the full Coffee monograph & all interactions
Keep checking

Other Drugs & Coffee

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

7Major
467Moderate
116Minor
2,239No known interaction
7 Major 467 Moderate 116 Minor 2,239 No interaction
Major

7 interactions

Moderate

467 interactions

Showing 60 of 467 moderate interactions — see all 467 on the Coffee page.

Minor

116 interactions

Showing 60 of 116 minor interactions — see all 116 on the Coffee page.

No interaction 2,239 drugs checked — show the list

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

Showing the 60 most looked-up of 2,239 medications checked with no known interaction — see the full Coffee list.

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

Can you take Coffee 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 3 interactions listed for Coffee and Ephedrine, Phenobarbital, Theophylline?
Ephedrine, Phenobarbital, Theophylline belongs to more than one drug category, and Coffee 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 Coffee 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

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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.