Drug & supplement interaction

Ilex Guayusa + Metaproterenol

Metaproterenol brand names: Metaproterenol, Metaprel.

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

Ilex Guayusa has a moderate interaction with Metaproterenol. Theoretically, concomitant use of large amounts of Ilex guayusa might increase cardiac inotropic effects of beta-agonists.

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

Ilex Guayusa and Metaproterenol

Here is the interaction we found between these two, with the evidence behind it.

Moderate

BETA-ADRENERGIC AGONISTS

Why this applies to Metaproterenol

Metaproterenol falls under BETA-ADRENERGIC AGONISTS — the group Ilex Guayusa interacts with.

Theoretically, concomitant use of large amounts of Ilex guayusa might increase cardiac inotropic effects of beta-agonists.
Ilex guayusa contains caffeine. Caffeine can increase cardiac inotropic effects of beta-agonists.
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 simple version. Metaproterenol is a quick-relief inhaler that opens your airways, but like other beta-agonists it can also rev up your heart a bit, sometimes causing a faster heartbeat, palpitations, or the jittery, shaky feeling many people notice after using their rescue inhaler. Guayusa tea is basically a caffeine source, and caffeine is a stimulant too.

So stacking the two could add up and make those heart-pounding, jittery effects more noticeable. To be clear, this is a theoretical concern based on how the two work, not something proven in studies, and it mostly applies to large, concentrated amounts of guayusa rather than an occasional cup. Still, if you feel your heart racing, mention it to your pharmacist or doctor before making any changes.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. McEvoy GK, ed. AHFS Drug Information. Bethesda, MD: American Society of Health-System Pharmacists, 1998.

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

Ilex Guayusa Also Interacts With Other Medications

Ilex Guayusa has 8 major, 469 moderate, 127 minor known drug interactions in our database — the Metaproterenol one above is one of them. If you take anything else, check it against the full list below.

Major 8 Moderate 469 Minor 127 No known interaction 2,226 (incl. Metaproterenol)
Taking anything else?

Check Another of Your Medications Against Ilex Guayusa

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

Everything else you take

See Every Supplement That Interacts With Metaproterenol

This page covers Ilex Guayusa only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Metaproterenol page lists 32 supplements it has a documented interaction with, worst first, each one explained.

The most serious there right now: Activated Charcoal (major), Black Tea (moderate), Caffeine (moderate), Cocoa (moderate) and Coffee (moderate).

By severity: 1 major · 22 moderate · 9 minor.

From our pharmacist’s overview on the Metaproterenol page

“Metaproterenol is an older bronchodilator for asthma and COPD, and because the receptors it stimulates to open the airways also quicken the heart, its 32 interacting supplements call for real vigilance. The lone major entry is activated charcoal, which can bind the drug and cut how much reaches your bloodstream.”

Reviewed by 2 · Jul 18, 2026

Open the Metaproterenol interaction page

How much people look this up

Where Ilex Guayusa and Metaproterenol 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 Ilex Guayusa
Top half

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

29 days ago today
Medication Metaproterenol
Steady interest

#2,196 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 Ilex Guayusa

What is Ilex Guayusa?

  • Energy and alertness
  • Mental focus
  • Antioxidant support
  • Appetite control
  • Athletic and physical performance

Ilex guayusa is a caffeine-containing holly leaf from the Amazon, traditionally brewed as a tea for energy and alertness, much like yerba mate or green tea. There is limited human research confirming specific health benefits, and its main reliable effect comes from its caffeine content. Because it is a stimulant, use it cautiously and check with your pharmacist or doctor if you have heart concerns or are pregnant.

Read the full Ilex Guayusa monograph & all interactions
Medication

About Metaproterenol

What Is Metaproterenol Used For?

Brand names: Metaproterenol, Metaprel

  • Metaproterenol is used to prevent and treat wheezing, shortness of breath, coughing, and chest tightness caused by asthma, chronic bronchitis, emphysema, and other lung diseases. It relaxes and opens air passages in the lungs, making it easier to breathe.

See full Metaproterenol drug information
Keep checking

Other Drugs & Ilex Guayusa

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

8Major
469Moderate
127Minor
2,225No known interaction
8 Major 469 Moderate 127 Minor 2,225 No interaction
Major

8 interactions

Moderate

469 interactions

Showing 60 of 469 moderate interactions — see all 469 on the Ilex Guayusa page.

Minor

127 interactions

Showing 60 of 127 minor interactions — see all 127 on the Ilex Guayusa page.

No interaction 2,225 drugs checked — show the list

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

Showing the 60 most looked-up of 2,225 medications checked with no known interaction — see the full Ilex Guayusa list.

See the full Ilex Guayusa interactions page
See every supplement checked against Metaproterenol, 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
Ilex Guayusa monograph › Uses, safety, and every drug interaction in one place Metaproterenol supplement interactions › Every supplement checked against Metaproterenol, ranked by severity Metaproterenol drug information › The full plain-English guide to this medication 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 Ilex Guayusa and Metaproterenol Together: Common Questions

Can you take Ilex Guayusa with Metaproterenol?
There is a moderate interaction, so it may be acceptable with monitoring or timing changes — but check with your pharmacist first. Read the full details on this page and confirm with your pharmacist before combining them.
How serious is the Ilex Guayusa and Metaproterenol interaction?
We rate it Moderate. This combination may require monitoring, a dose adjustment, or separating the times you take each one. Consult your pharmacist before using them together.

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

Still Have a Question About Metaproterenol and Ilex Guayusa?

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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.