Drug & supplement interaction

Ilex Guayusa + Isoproterenol

Isoproterenol brand name: Isuprel.

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

Ilex Guayusa has a moderate interaction with Isoproterenol. 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?
Know someone taking this? Share
Facebook Post Reddit Email
On this page
Interaction report

Ilex Guayusa and Isoproterenol

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

Moderate

BETA-ADRENERGIC AGONISTS

Why this applies to Isoproterenol

Isoproterenol 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

Isoproterenol (Isuprel) is a beta-agonist that revs up your heart, making it beat faster and squeeze harder. Guayusa is basically a caffeine source, and caffeine is a stimulant too. So putting the two together is a bit like pressing the same gas pedal twice. In theory, the caffeine could add to isoproterenol's punch on the heart, leaving you more likely to feel a racing or pounding heartbeat, palpitations, jitteriness, or a flushed, anxious feeling.

I want to be honest about the strength of this: it is a theoretical concern based on how these compounds work, not on hard human studies. An occasional cup of guayusa is unlikely to cause real trouble, but large or concentrated amounts deserve more caution. Since isoproterenol is usually given in a medical setting, just let your care team know if you use caffeine-rich supplements.

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 Isoproterenol 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. Isoproterenol)
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 Isoproterenol

This page covers Ilex Guayusa only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Isoproterenol page lists 16 supplements it has a documented interaction with, worst first, each one explained.

The most serious there right now: Black Tea (moderate), Caffeine (moderate), Cocoa (moderate), Coffee (moderate) and Cola Nut (moderate).

By severity: 16 moderate.

From our pharmacist’s overview on the Isoproterenol page

“Isoproterenol (Isuprel) is a heart stimulant, usually given in a hospital to speed up a dangerously slow heartbeat, and all 16 supplement interactions on record with it are rated moderate, none major. That makes this a list to know rather than fear.”

Reviewed by 2 · Jul 18, 2026

Open the Isoproterenol interaction page

How much people look this up

Where Ilex Guayusa and Isoproterenol 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
Steady interest

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

29 days ago today
Medication Isoproterenol
Steady interest

#2,460 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
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 Isoproterenol, 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 Isoproterenol supplement interactions › Every supplement checked against Isoproterenol, 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 Ilex Guayusa and Isoproterenol Together: Common Questions

Can you take Ilex Guayusa with Isoproterenol?
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 Isoproterenol 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 Isoproterenol and Ilex Guayusa?

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.