The short answer
A harmful interaction between yerba mate and oral phenylephrine has not been established in the sources checked. Yerba mate can supply caffeine, so the drink or supplement may add to caffeine already present in a cold medicine or other products. The amount and preparation matter.
What this answer covers
Oral phenylephrine hydrochloride with Ilex paraguariensis leaf preparations. Brewed mate, concentrated extracts and mixed energy products are different exposures. The inspected mouse study used injected phenylephrine as a separate comparator.
- Supplement or preparation
- Ilex paraguariensis
- Medication ingredient
- phenylephrine
Does the type of mate product matter?
Yes. NIH identifies yerba mate as a botanical source of caffeine, sometimes listed without the total caffeine amount on supplement labels. A brewed drink, concentrated capsule and multi-ingredient energy product can provide different exposures. Record the serving size and all added ingredients.
What does the study mentioning both names show?
The inspected study tested pain responses in mice. Yerba mate was given orally, while phenylephrine was injected into the abdomen in separate comparator groups. Shared sensitivity to a receptor-blocking drug suggested a possible mechanism; it did not show that taking mate with phenylephrine increases side effects in people.
Where does the practical caution come from?
It comes mainly from caffeine and the medicine's own precautions. A phenylephrine, caffeine and paracetamol product warns against excessive extra caffeine. That supports checking a caffeine-containing mate product, while leaving the exact herb-drug interaction unproven.
Would spacing the doses make co-use safe?
No validated interval was identified. A phenylephrine-only trial excluded caffeine and herbs, so it cannot answer the timing question. Have a pharmacist review your actual mate preparation and medicine, particularly when several products contribute caffeine.
Evidence and practical considerations
Side effects & toxicity
The exact human oral pair remains unconfirmed. Caffeine-containing yerba mate can add stimulant exposure, but a mouse pain experiment using separate phenylephrine groups does not demonstrate increased co-use toxicity.
- Exact scope
- Oral phenylephrine hydrochloride with Ilex paraguariensis leaf preparations. Brewed mate, concentrated extracts and mixed energy products are different exposures. The inspected mouse study used injected phenylephrine as a separate comparator. with oral phenylephrine hydrochloride supplying the exact phenylephrine active moiety, RxCUI 8163
- Medication form and route
- oral
- Timing or duration
- During co-use; source-specific durations are retained without inferring a universal safe duration.
What remains uncertain
- No human oral pair trial located. Botanical caffeine content varies; the available mechanism experiment used mice, a pain endpoint and a different phenylephrine route.
Factors that may matter: mate preparation and serving size; caffeine amount; other energy-product ingredients; phenylephrine route.
Read the supporting source summaries
Source 1: regulatory product information
medicines.org.uk · Source check Sep 10, 2026
Population: People using this oral cold and flu combination product, age 16 years and older.
The product combines phenylephrine and caffeine, warns against excessive additional caffeine, and lists hypertension and heart disease among contraindications. Caffeine and phenylephrine adverse effects include palpitations and sleep-related symptoms.
How this applies: Exact phenylephrine active moiety and caffeine co-formulation. Botanical applicability is an inference only when the supplement actually supplies caffeine; other herb constituents and other phenylephrine routes are not evaluated.
Instructions apply to this finished oral product. They neither establish a universal caffeine threshold or spacing interval nor prove safety of isolated phenylephrine with supplements. Other ingredients confound extrapolation.
Source 2: government evidence summary
ods.od.nih.gov · Source check Sep 10, 2026
Population: People using weight-loss supplements; underlying studies vary.
These plants can supply caffeine. Green coffee extracts can be decaffeinated; green tea preparations range from leaves to isolated constituents. Some labels fail to disclose caffeine quantities. Bitter-orange cardiovascular findings are inconsistent.
How this applies: Supports preparation-specific identity and caffeine assessment, not proof that the exact herb increases phenylephrine toxicity. General healthy-adult caffeine limits are not treated as safe co-use thresholds.
No exact phenylephrine interaction trial is established by this summary. Effects of one constituent or mixture cannot be assigned to every botanical preparation.
Source 3: animal mechanism experiment
pmc.ncbi.nlm.nih.gov · Source check Sep 10, 2026
Population: Adult Swiss mice.
Prazosin reversed analgesic responses to both Ilex and phenylephrine in separate groups. Caffeine and theobromine were detected in the infusion.
How this applies: An exact-name search hit that cannot substantiate the clinical pair claim; supports careful interpretation of shared receptor pathways.
Pain behavior in mice, not cardiovascular co-use. The study did not give oral phenylephrine together with Ilex to test toxicity.
Source 4: randomized placebo-controlled crossover study
pmc.ncbi.nlm.nih.gov · Source check Sep 10, 2026
Population: Twenty-eight healthy normotensive adults.
Cardiovascular tolerability was broadly comparable with placebo. Exposure increased more than proportionally with dose; individual concentrations varied substantially.
How this applies: Medication-only evidence prevents presenting every oral phenylephrine dose as inevitably raising blood pressure. It does not show that any supplement combination is safe.
Selected healthy participants, single doses, no supplement co-use. The authors state the design does not adequately assess proarrhythmic risk. Sponsor funded the study and authors were sponsor employees.
Research assessment: · Open full citations ↗
Review and change history
- Publication status
- Published research summary
- Clinical review
- Not yet recorded
| Date | Update |
|---|---|
| Article prepared | |
| Reframed the broad risk claim around caffeine exposure and lack of direct human pair evidence. Added the original Ilex experiment's separate comparator groups and intraperitoneal phenylephrine route. | |
| Research summary published |
Article revision: e79880cd9812d760
This guide brings together the evidence records used by our interaction checker. Each finding retains its own preparation limits, research date, and source summaries.
Full citations require verification. Reading this answer and the source summaries does not.
Taking other supplements or medications?
Use the checker to explore your other combinations. Ask a pharmacist to review the exact products, amounts and medical conditions in your complete list.
Open the interaction checkerInformation, not medical advice. Do not change prescribed treatment based on this guide.