Drug & supplement interaction

Ilex Guayusa + Phenylpropanolamine

Phenylpropanolamine brand names: Dexatrim, Propagest, Revive Diet Aid, Mini Thin Diet Aid, Mini Slims, and others.

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

Phenylpropanolamine falls into 2 drug categories that Ilex Guayusa can interact with; the most serious is rated moderate. Theoretically, concomitant use might increase stimulant adverse effects.

Read the full interaction report
SeverityModerate
LikelihoodProbable
Interactions2
EvidenceC
What do Severity, Likelihood & Evidence mean?
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Interaction report

Ilex Guayusa and Phenylpropanolamine

These two interact in 2 distinct ways. Each one is explained separately below.

Why Are There 2 Interactions?

Ilex Guayusa interacts with whole categories of medication. Phenylpropanolamine falls into 2 of those categories, so it can interact with Ilex Guayusa in 2 different ways. We’ve listed each one below — your overall risk is driven by the most serious of them (Moderate).

Moderate

STIMULANT DRUGS

1 of 2

Why this applies to Phenylpropanolamine

Phenylpropanolamine falls under STIMULANT DRUGS — the group Ilex Guayusa interacts with.

Theoretically, concomitant use might increase stimulant adverse effects.
Ilex guayusa 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: guayusa is basically a caffeine source, and phenylpropanolamine is itself a stimulant that was used as a decongestant and diet aid. Stack a stimulant on top of a stimulant and you can add up their effects. So pairing the two could leave you feeling jittery, anxious, or restless, with a faster or pounding heartbeat, higher blood pressure, trouble sleeping, and headache.

This is a theoretical concern based on expert opinion rather than hard studies, so it isn't a guaranteed reaction. A single cup of guayusa tea is far milder than concentrated supplement doses. Still, if you have any heart or blood pressure concerns, please check with your pharmacist or doctor before combining them.

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

PHENYLPROPANOLAMINE

2 of 2
Theoretically, phenylpropanolamine might increase the risk of hypertension, as well as the levels and adverse effects of caffeine.
Ilex guayusa contains caffeine. Concomitant use of phenylpropanolamine and caffeine might cause an additive increase in blood pressure. Phenylpropanolamine also seems to increase caffeine serum 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

Here's the thing with pairing guayusa and phenylpropanolamine: both can push your blood pressure up, and stacking them together can add up. Phenylpropanolamine is a stimulant decongestant and appetite suppressant, and guayusa is essentially a caffeine-rich tea. Together you may notice a racing or pounding heart, jitteriness, headache, trouble sleeping, or a real bump in blood pressure.

There's also a two-way piece: phenylpropanolamine seems to slow how your body clears caffeine, so the caffeine from guayusa can build up and feel stronger than usual. The evidence here is modest, but the blood-pressure concern is real enough that I'd run this by your pharmacist or doctor before combining them, especially if you have any heart or blood-pressure issues.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Brown NJ, Ryder D, Branch RA. A pharmacodynamic interaction between caffeine and phenylpropanolamine. Clin Pharmacol Ther 1991;50:363-71. PubMed
  2. Lake CR, Rosenberg DB, Gallant S, et al. Phenylpropanolamine increases plasma caffeine levels. Clin Pharmacol Ther 1990;47:675-85. 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

Ilex Guayusa Also Interacts With Other Medications

Ilex Guayusa has 8 major, 469 moderate, 127 minor known drug interactions in our database — the Phenylpropanolamine one above is among 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. Phenylpropanolamine)
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 Phenylpropanolamine

This page covers Ilex Guayusa only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Phenylpropanolamine page lists 62 supplements it has a documented interaction with, worst first, each one explained.

The most serious there right now: Activated Charcoal (major), Ephedra (major), Peyote (major), Rauvolfia Vomitoria (major) and Sida Cordifolia (major).

By severity: 5 major · 44 moderate · 13 minor.

From our pharmacist’s overview on the Phenylpropanolamine page

“Phenylpropanolamine (Dexatrim, Propagest) is a stimulant decongestant and diet aid that raises blood pressure on its own, so I read its supplement interactions with real vigilance. Of the 62 ingredients on file, 44 are stimulants themselves, and stacking them can push heart rate and blood pressure into risky territory.”

Reviewed by 2 · Jul 18, 2026

Open the Phenylpropanolamine interaction page

How much people look this up

Where Ilex Guayusa and Phenylpropanolamine 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 Phenylpropanolamine
Steady interest

#1,756 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 Phenylpropanolamine, 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 Phenylpropanolamine supplement interactions › Every supplement checked against Phenylpropanolamine, 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 Phenylpropanolamine Together: Common Questions

Can you take Ilex Guayusa with Phenylpropanolamine?
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.
Why are there 2 interactions listed for Ilex Guayusa and Phenylpropanolamine?
Phenylpropanolamine belongs to more than one drug category, and Ilex Guayusa 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 Ilex Guayusa and Phenylpropanolamine 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

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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.