Drug & supplement interaction

Yerba Mate + Conjugated Estrogens

Conjugated Estrogens brand names: Premarin, Cenestin, Enjuvia, Premarin Vaginal Cream.

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

Conjugated Estrogens falls into 2 drug categories that Yerba Mate can interact with; the most serious is rated moderate. Theoretically, estrogens might increase the levels and adverse effects of the caffeine in yerba mate.

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

Yerba Mate and Conjugated Estrogens

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

Why Are There 2 Interactions?

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

Moderate

ESTROGENS

1 of 2

Why this applies to Conjugated Estrogens

Conjugated Estrogens falls under ESTROGENS — the group Yerba Mate interacts with.

Theoretically, estrogens might increase the levels and adverse effects of the caffeine in yerba mate.
Yerba mate contains caffeine. Estrogen inhibits caffeine metabolism.
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 simple version: this isn't your estrogen building up, it's the caffeine in yerba mate that hangs around longer. Conjugated estrogens like Premarin can slow down the liver enzyme that clears caffeine, so the same cup of mate may hit you harder and stick with you longer than usual.

In real life that can mean feeling jittery, a racing or pounding heart, trouble sleeping, headaches, or an upset stomach. The estrogen itself works the same either way, so this won't make your menopause treatment stronger or weaker. If you notice more of these caffeine-type effects, it's reasonable to cut back on mate (and other caffeine) and chat with your pharmacist. An occasional cup is usually no big deal.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Pollock BG, Wylie M, Stack JA, et al. Inhibition of caffeine metabolism by estrogen replacement therapy in postmenopausal women. J Clin Pharmacol 1999;39:936-40. PubMed
Minor

CYTOCHROME P450 3A4 (CYP3A4) SUBSTRATES

2 of 2

Conjugated Estrogens also falls under CYTOCHROME P450 3A4 (CYP3A4) SUBSTRATES.

Theoretically, yerba mate might increase the levels and clinical effects of CYP3A4 substrates.
In vitro research shows that yerba mate extract inhibits CYP3A4 enzymes. Theoretically, taking yerba mate may increase levels and adverse effects of CYP3A4 substrates.
Severity Minor Likelihood Possible Evidence D

Interaction 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.

Dr. Brian Staiger, PharmD, BCPS
Dr. Brian Staiger explains PharmD, Clinical Pharmacist

Here's the gist: your body uses an enzyme called CYP3A4 to help break down conjugated estrogens (Premarin and similar). In lab dishes, yerba mate has been shown to slow that enzyme down a bit. If that happened in real life, your estrogen could clear a little more slowly and build up, which in theory might bump up estrogen-related effects like breast tenderness, bloating, nausea, headaches, or spotting.

The honest truth, though, is that this is based only on test-tube research, not on people, and it's rated as a minor interaction. For most folks, enjoying yerba mate in normal amounts is unlikely to cause a real problem. If you drink a lot of it daily or notice new symptoms, just check in with your pharmacist or doctor so they can look at your whole picture.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Feltrin C, Farias IV, Sandjo LP, Reginatto FH, Simões CMO. Effects of Standardized Medicinal Plant Extracts on Drug Metabolism Mediated by CYP3A4 and CYP2D6 Enzymes. Chem Res Toxicol 2020;33(9):2408-2419. 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

Yerba Mate Also Interacts With Other Medications

Yerba Mate has 8 major, 504 moderate, 573 minor known drug interactions in our database — the Conjugated Estrogens one above is among them. If you take anything else, check it against the full list below.

Major 8 Moderate 504 Minor 573 No known interaction 1,745 (incl. Conjugated Estrogens)
Taking anything else?

Check Another of Your Medications Against Yerba Mate

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

Everything else you take

See Every Supplement That Interacts With Conjugated Estrogens

This page covers Yerba Mate only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Conjugated Estrogens page lists 207 supplements it has a documented interaction with, worst first, each one explained.

The most serious there right now: Activated Charcoal (major), Grapefruit (major), St. John's Wort (major), Tiratricol (major) and Acacia Rigidula (moderate).

By severity: 4 major · 172 moderate · 31 minor.

From our pharmacist’s overview on the Conjugated Estrogens page

“Conjugated estrogens (Premarin, Cenestin) are hormone replacement, most often for menopause symptoms, and the 207 supplements here warrant real care before adding any of them. Most of the risk runs through drug processing: 121 entries involve the CYP3A4 enzyme that clears estrogen, which is how St.”

Reviewed by 2 · Jul 18, 2026

Open the Conjugated Estrogens interaction page

One more smart check

Taking Yerba Mate as Part of a Dietary Supplement Product? Check It for Interactions

We hold 68 real supplement products containing Yerba Mate, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Yerba Mate. Your product may carry other ingredients that interact with Conjugated Estrogens too, on top of Yerba Mate — 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 Yerba Mate and Conjugated Estrogens 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 Yerba Mate
Steady interest

#1,100 of 1,452 supplements looked up here in the last 7 days

29 days ago today
Medication Conjugated Estrogens
Steady interest

#1,492 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 Yerba Mate

What is Yerba Mate?

Yerba Mate
  • Energy and alertness
  • Weight loss
  • Mental focus
  • Digestive support
  • Antioxidant support

Yerba mate is a caffeine-containing herbal beverage from South America that is widely enjoyed for its stimulating, coffee-like effects. While it is rich in antioxidants and is being studied for weight, blood sugar, and cholesterol, strong human evidence for most health claims is limited. Drinking very hot mate over many years has been linked to higher risk of certain cancers, so enjoy it warm and in moderation.

Read the full Yerba Mate monograph & all interactions
Keep checking

Other Drugs & Yerba Mate

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

8Major
504Moderate
573Minor
1,744No known interaction
8 Major 504 Moderate 573 Minor 1,744 No interaction
Major

8 interactions

Moderate

504 interactions

Showing 60 of 504 moderate interactions — see all 504 on the Yerba Mate page.

Minor

573 interactions

Showing 60 of 573 minor interactions — see all 573 on the Yerba Mate page.

No interaction 1,744 drugs checked — show the list

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

Showing the 60 most looked-up of 1,744 medications checked with no known interaction — see the full Yerba Mate list.

See the full Yerba Mate interactions page
See every supplement checked against Conjugated Estrogens, 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
Yerba Mate monograph › Uses, safety, and every drug interaction in one place Conjugated Estrogens supplement interactions › Every supplement checked against Conjugated Estrogens, 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 Yerba Mate and Conjugated Estrogens Together: Common Questions

Can you take Yerba Mate with Conjugated Estrogens?
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 Yerba Mate and Conjugated Estrogens?
Conjugated Estrogens belongs to more than one drug category, and Yerba Mate 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 Yerba Mate and Conjugated Estrogens 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 Conjugated Estrogens and Yerba Mate?

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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.